ELECTRICITY & MAGNETISMCoulomb’s Law – law that describes the force of attraction or repulsion between two charges is directly proportional to their strengths and inversely proportional to the square of the distance between them. The basic law for interaction of charged bodies at rest.Coulomb’s first law of electrostatics – law that describes the force of attraction or repulsion between two magnetic poles is directly proportional to their strengths.Coulomb’s second law of electrostatics – law that describes the force of attraction or repulsion between poles is inversely proportional to the square of the distance between them.Gauss’s Law – The summation of the normal component of the electric field displacement E over any closed surface is directly proportional to the electric charge within the surface.Faraday’s Law – States that the magnitude of the emf induced in a circuit is proportional to the rate of change of the magnetic flux that cuts across it.Faraday’s first Law – Electromotiveforce (emf) is induced whenever a conductor cuts magnetic flux.Faraday’s second Law – The magnitude of electromotiveforce (emf) s induced when a conductor cuts magnetic flux is directly proportional to its rate.Faraday’s Law – In Electromagnetism, the law that determines the amount of induced voltage.Lenz’ Law – In Electromagnetism, the law that determines the polarity of an induced voltageLenz’ Law – In all cases of electromagnetic induction, the current setup by an induced voltage tends to create flux whose direction opposes any change in the existing flux.Lenz’s Law – In electronics, an induced current will be in such a direction that its own magnetic field will oppose the magnetic fields that produce the same.Curie’s Law – States that the magnetic susceptibilities of most paramagnetic substance are inversely proportional to their absolute temperature.Curie-Weiss Law – relating between the magnetic and electric susceptibilities and the absolute temperatures which is followed by ferromagnets, antiferromagnets, non-polar ferroelectrics, paramagnts.Child’s Law – States that the current in a thermionic diode varies directly with the three-halves power of anode voltage and inversely with the square of the distance between the electrodes.Wiedemann-Franz Law - States that the ratio of the thermal conductivity to the electric conductivity is proportional to the absolute temperature for metalAmpere’s circuital Law – A law establishing the fact that the algebraic sum of rises and drops of the mmf around a closed loop of a magnetic circuit is 0.Law of conservation of energy – “The net electric charge in an isolated system remains constant”Wiegand effect – The effect that describes the ability of a mechanically stressed ferromagnetic wire to recognize rapid switching of magnetization when subjected to a DC magnetic field.Hall effect –small voltage is generated by a conductor with current in an external magnetic field. Used in the gaussmeter to measure flux density.Edison effect – The emission of electrons from hot bodiesWall effect – ionization by electrons liberated from the wallsBridgman effect – phenomenon that when an electric current passes through an arisotropic crystal, there is an absorption or liberation of heat.Weber’s Theory of Magnetism – Assumes that all magnetic substance is composed of tiny molecular magnets.Domain Theory – theory based on the electron spin theory; If an atom has an equal number of electrons spinning in opposite directions, the magnetic field surrounding the electron cancel one another, the atom is unmagnetized.Ewing’s Theory of ferromagnetism – assumes each atom is a permanent magnet which can turn freely about its center under the influence of applied fields and other magnetsExclusion Principle – States that each electron in an atom must have a different set of quantum numbers.Pauli exclusion principle – states that only two electrons with different spins are allowed to exist in a given orbitHans Christian Oersted – relationship between magnetism and electricityMichael Faraday – theory of electromagnetic induction, 1891James Clerk Maxwell – electromagnetic theory of light, 1862Andre Ampere – current carrying conductor can attract & repel like magnet

Kamerlingh Onnes – Superconductivity, 1911Self induced emf –due to the change of its own flux linked with itMutually induced emf – to the changing current of another neighboring coilStatically induced emf – conductor is stationary, magnetic field is movingUnit pole – pole which when placed in air from a similar and equal pole repels it with force of 1/4piu newtonsMagnetic pole – the intensity of magnetic lines of force is maximum.North pole – pole where magnetic lines of force are originatingDiamagnetic – permeability slightly less than that of free spaceParamagnetic – permeability slightly greater than that of free spaceFerromagnetic – have very high permeabilitiesConductor – valence electron less than 4Semiconductor – valence electron equal to 4Insulator – valence electron greater than 4Metallic bond – bonding of atoms that is due to the force of attraction between positive ions and a group of negative ions.Ionic bond – formed when one or more electrons in the outermost energy orbit of an atom are transferred to another.Covalent bond – formed when electrons in the outermost energy orbits of the atoms are shared between two or more electronsVan der Waals bond – formed when there exist distant electronic interactions between charges present in the neighboring atomsPermalloy – iron 22%, nickel 78%Hipernik – iron 40%, nickel 60%Alnico – aluminum, nickel, iron, cobalt, copper, titanium at 12 gradesManganin – 84% copper, 12% manganese and 4% nickelVector quantity – Magnetic field intensity, field, magnetic intensity, electric flux density, electric field intensityScalar quantity – Electric potential, electric fluxInsulator – widest gap between valence band and the conduction bandConductor – smallest gap between valence band and the conduction bandBand gap – difference in energy between the valence and conduction bandCrystalline – solids in which the position of atoms are predeterminedAmorphous/Non-crystalline – has no defined crystal structureMica – used as the insulating material or dielectric in an electric ionGlass – has the highest dielectric strengthPorcelain – used as the dielectric material in high voltage transformersQuantum – definite discrete amount of energy required to move an electron from a lower shell to a higher shell.Amber – means elektron in GreekValence band – series of energy levels containing the valence electronPlasma – gases with charged particleElectric dipole – a combination of two charges, with equal charge magnitude but opposite signsKeeper – used to maintain strength of magnetic fieldToroid – an electromagnet with its core in the form of a close magnetic ringdomain - A group of magnetically aligned atomsthermonic emission - Evaporation of electron from a heated surface Back emf - refers to the voltage opposing the applied emfMadelung constant – factor used to correct for the electrostatic forcesMagnetic material loss its ferromagnetic properties at a point called Curie temperatureThe dielectric constant of most materials lies between 1 and 101.15 to 1.25 is the usual value of leakage coefficient for electrical machinesCurrent carriers in conductors are valence electronsDielectric is another name for insulatorRF current flow along the surface.Because of skin effect resistance is different for RF current then DCSteel is hard to magnetize because of its low permeabilityOne of the common application of an air-cored choked is at Radio frequencyOhm’s law can be used only to a linear circuit or componentMagnetic field around the conductor is determined by the amount of currentIn electro-mechanical conversion device, the reason why a small air gap is left between the rotor and stator is to permit mechanical clearance.Permanent magnets can be found in earphonesTemporary magnets are commonly employed in motorsHardened steel is used by permanent magnets as the magnetic material

Soft iron is used by temporary magnets as the magnetic materialSilicon steel materials has the least hysteresis loop area

Magnetomotive force (mmf)

Ampere-TurnAT

GilbertGb

1 AT = 1.257 Gb

Magnetic Field Strength

Ampere per meter A/m

OerstedOe (Gb/cm)

1 A/m = 0.01257 Oe

Magnetic Flux Weber Wb Maxwell Mx 1 Wb = 10^8 Mx

Magnetic Flux density

TeslaT (Wb/m^2)

GaussG (Mx/cm^2)

1T = 10^4 G

V Volt Emf Mmf Amp-turn

I Amp Current Magnetic flux WeberR Ohm Resistance Reluctance 1/H

V/m Field strength Magnetization Amp/m H

J A/m Current density Flux density Tesla B

Ohm-m Resistivity Reluctivity m/H VG Siemens Conductance Permeance Henry P

S/m Conductivity Permeability H/m

ELECTRICAL CIRCUITSKirchhoff’s first law – The sum of all currents entering a junction is equal to the sum of currents leaving away from that junction.Kirchhoff’s second law – In a mesh, the algebraic sum of all voltages and voltages drops is equal to zero.CR Law – a law which states that when a constant electromotive force is applied to a circuit consisting of a resistor and capacitor connected in series, the time taken for the potential on the plates of the capacitor to rise to any given fraction of its final value depends only on the product of capacitance and resistance.Thevenin’s theorem – Used to simplify complex circuits wherein, the simplified circuit contains an equivalent open circuit resistance and open circuit voltage.Norton’s theorem – reverse of Thevenin’s theoremIn Norton’s theorem, the short circuit current is obtained by shortening the load terminalsSuperposition theorem – Used in solving electrical circuits with several voltage sources.Superposition theorem – Used in simplifying circuit analysis by considering the effect of supply voltages one at a time.The superposition theorem is used when the circuit contains a number of voltage sources.Compensation theorem – “Any resistance R in a branch of a network in which a current I is flowing can be replaced by a voltage equal to IR”.Reciprocity theorem – If an emf in circuit A produces a current in circuit B, then the same emf in circuit B produces the same current in circuit A.Edge effect – refers to the outward-curving distortion of the lines of force near the edges of two parallel metal plates that form a capacitor.Mesh – A chosen closed path of current flow in a network.Loop – A set of circuit elements that forms a closed path in a network over which signal can circulateNode – a reference point chosen such that more branches in a circuit metJunction – A common connection between circuit elements or conductors from different branches.Ground – return point in a circuit, where all voltage measured are referred.KVL – Mesh analysisKCL – Nodal analysisTrue power – the power dissipated across the resistance in an AC circuit.A series circuit at resonance would mean, the circuit is resistiveA parallel circuit at resonance would mean, the circuit is resistiveIn ac-circuit, if the voltage and current are in phase, the circuit is resistive.If the current and voltage has a phase difference, the circuit is reactive.If the current in ac-circuit leads the voltage by 90, the circuit is capacitive.If the current in ac-circuit lags the voltage by 90, the circuit is inductive.In a series ac-circuit, if the line frequency is more than the resonant frequency, the circuit behaves as inductive.If the line frequency of a parallel ac-circuit is less than the resonant frequency, the circuit behaves as reactive.If an ac-series circuit is supplied with a source whose frequency is less than that of fr, the circuit becomes capacitive.Smaller resistors usually have high resistance value.When the temperature of a copper wire is increased, its resistance is increased.The resistance of an insulator decreases when its temperature is increased.Skin effect increases the resistance of wire at high frequenciesThe result of rust in electrical wire connection is resistanceWattage rating of a resistor determines its ability to absorb heat.Resistors with high value usually have lower wattage rating because of lower currentHigh resistance values are a consequence of the thinness of the film.A disadvantage of a wire-wound resistor is that it has reactance in radio-frequency circuits.Bifilar resistor – a resistor wound with a wire doubled back on itself to reduce the inductance.A rheostat is a form of variable resistor.Air dielectric is generally employed by a variable capacitor.Barium-strontium titanite dielectric material is also called ceramicPaper has the lowest dielectric strengthBarium-strontium titanite dielectric makes the highest-capacitance capacitor.Electrolytic capacitors are used only in dc circuits.Electrolytic capacitor has the highest cost per microfarad.Electrolytic capacitor is suitable for dc filter circuits.A capacitor consists of conductors separated by a dielectricThe capacitance of a capacitor is directly proportional to relative permittivity.In a multiplate capacitor, the plate area is increased.For mutli-plate capacitor, capacitance is proportional to number of plates less one (n-1).A capacitor is used to block dc current

The charging of a capacitor through a resistance obeys exponential law.It is impossible to change the voltage across a capacitor instantly, as this would produce infinite current.Leakage resistance in a capacitor results into internal heatingA capacitor opposes change in voltage.Capacitance increases with larger plate area and less distance between platesIncreasing capacitance is considered the effect of a dielectric material.A gang capacitor is a variable capacitor in which capacitance is varied by changing the plate areaA trimmer is a variable capacitor in which capacitance is varied by changing the distance between platesStray capacitance exist not through design but simply because two conducting surface are relatively close to each other.The ratio between the active power and the apparent power of the load in an ac circuit is called power factor.An inductive load always has a lagging power factor.The power factor of a series LC circuit is 0.The rms value of a triangular or sawtooth waveform is 0.577 times its peak value.The average value of triangular or sawtooth wave is 0.500 times its peak value.1.73 is the peak factor of a triangular wavePeak factor for alternating current or voltage varying sinusoidally, 1.4142The factor 0.707 for converting peak to rms applies only to sine waves.For a linear, rms voltage or current is used to calculate average power.The current is 0.707 times the maximum current at half-power points of a resonance curve.Zero reading on an ohmmeter for a shorted capacitorAn open resistor when checked with an ohmmeter reads infinite.Surge voltage is the maximum voltage that can be applied across the capacitor for very short period of time.Breakdown voltage refers to the lowest voltage across any insulator that can cause current flow.The ratio of the flux density to the electric field intensity in the dielectric is called permittivity.The ratio of maximum value to the effective value of an alternating quantity is called peak factor.The graph between an alternating quantity and time is called waveform.Reactance chart can be used to estimate resonant frequency and to find reactance at any frequency for any value of capacitor or inductor.Temperature coefficient of resistance – A factor that states how much the resistance changes for a change in temperature.The ohmic value of a resistor with negative temperature coefficient increases with decreasing temperature.Carbon has a negative temperature coefficient.Manganin has a positive temperature coefficientTungsten filament of bulbs has a hot resistance higher than its cold resistance due to its temperature coefficient which is positive.The temperature coefficient of resistance of electrolytes is negative.In a pure capacitance, current lead voltage by 90In an RL series circuit, current lags voltage by less than 90In a rectangular wave, form factor is 1.0In a triangular wave, form factor is 1.16For a series AC circuit, voltage is not used as a reference phasor.For a parallel AC circuit, voltage is used as a reference phasor.The Q-factor of a series resonant circuit is also known as voltage magnification factor.The Q-factor of a parallel resonant circuit is also known as current magnification factor.Parallel resonant circuit is sometimes called rejector circuit.Series resonant circuit is sometimes known as acceptor circuit.In dividing or multiplying phasor quantities, polar form is used.In adding or subtracting phasor quantities, rectangular form is used.Conventional flow assumes charges flow from positive to negative.Electron flow assumes charges flow from negative to positive.The symbol Q refers to quality factor.The reciprocal of quality factor is dissipation factor.Norton’s theorem – usually used in the analysis of transistor circuitThevenin’s theorem – generally used in the analysis of vacuum tubesNorton’s theorem is a form of current equivalent circuitThevenin’s theorem is a form of voltage equivalent circuitParallel resonant circuit is also known as anti-resonant circuitThe curve between current and frequency is termed as resonance curve.At parallel resonance, the current flowing through L and C are equal.Voltage resonance means series resonanceThe resonance curve is a plot of frequency versus current for a series RLC circuit.

Series resonant circuit is inductive if it operates at a frequency higher than the resonant frequency.When two complex conjugates are subtracted, the result is a quadrature component only.If two complex conjugates are added, in-phase component resultsAlloy is a fusion of elements, without chemical action between them.Anticapacitance switch – a switch designed to have low capacitance between its terminal when open.Phasor is a rotating vector whose projection can represent either current or voltage in an ac circuitCryogenic conductor – another term for superconductorFaradic current – An intermittent and non-symmetrical alternating current like that obtained from the secondary winding of an induction coil.Joules – the term used to express the amount of electrical energy stored in electrostatic field.Phasor quantity – refers specifically to steady state values of quantities in ac circuits which are complex numbers.Non-linear circuit – a circuit whose parameters change with voltage or currentLiquids that are good conductors because of ionization are called electrolytes.Manganin is a common material used in wire-wound resistors.Elastance is the reciprocal of capacitance.Permeability is otherwise known as magnetic conductivity.Effective value is considered as the most important value of a sine wave.Tank circuit is a parallel LC circuit.When current and voltage are in phase in an ac circuit, the reactance is equal to zero.The voltage cannot be exactly in phase with the current in a circuit that contains only capacitance.An open inductor has infinite resistance and zero inductance.The reciprocal of a complex number is a complex numberMetal tin becomes superconductor at approximately 3.7 K.A real current source has a large internal resistance.The reason why alternating current can induce voltage is it has a varying magnetic field.In an ac-circuit, the power dissipated as heat depends on resistance.The maximum power transfer theorem is used in electronic circuitsAccording to Gauss theorem, flux can be equated to charge.The phase of an alternating quantity is defined as the fractional part of a period or cycle through which the quantity has advanced from selected origin.The admittance of a parallel RLC circuit is found to be the phasor sum of conductance and susceptance.In an inductive coil, the rate of rise of current is maximum near the final maximum value of current. For a series circuit, the higher the quantity factor the narrower the passband.The impedance in the study of electronics is represented by resistance and reactance.An ideal current source has an internal conductance of zero siemen/s.Norton’s theorem is the converse of Thevenin’s theoremELECTRONIC DEVICESIntrinsic – the name of the semiconductor material that has an equal number of electrons and holesElement that has four valence electrons are classified as elemental semiconductorGermanium (Ge) – example of elemental semiconductorGallium Arsenide (GaAs), Gallium Phosphide (GaP), Aluminum Arsenide (AlAs) – example of a compound semiconductorCovelent bond – the chemical bond that is present in a crystal lattice of silicon atomsForbidden gap – the area that separates the valence band and the conduction band.At absolute zero temperature, semiconductor acts as an insulatorThe electron flow in a semiconductor material is opposite in direction of hole flow10 - 10^4 ohm-cm – typical range of the resistivity of a semiconductorMetallic bonding – chemical bond that is significant in metalsIntrinsic semiconductor – a semiconductor that is free from impuritiesDoping – the process of adding impurities in a semiconductorPentavalent – impurities with five valence electronsTrivalent impurities – Example of acceptor impuritiesIf the substance used in doping has less than four valence electrons, it is known as acceptorAntimony(Sb), Arsenic(As), Phosphorus(P) – commonly used as donor impuritiesBoron(B), Gallium(Ga), Indium(In) – Example of trivalent impuritiesDonor-doped semiconductor becomes an N-type semiconductorCompensated semiconductor – a semiconductor that is doped with both donor and acceptor impuritiesThe resistance of a semiconductor is known as bulk resistance

Silicon – the most extensively used semiconductorIntrinsic semiconductor – semiconductor whose electron and hole concentrations are equalSilicon is widely used over germanium due to its low leakage currentDrift current – current flow in a semiconductor that is due to the applied electric fieldDiffusion current – the movement of charge carriers in a semiconductor even without the application of electric potentialTypically, 0.05 eV energy is required for a valence electron to move to the conduction band for a doped semiconductorConduction of electrons in a doped semiconductor happens at conduction bandValence band – where the conduction of holes occur in a doped semiconductorIn energy band diagram of a doped semiconductor, the donor level is near the conduction bandThe acceptor level in a doped semiconductor is near the valence band levelIn a semiconductor material, the number of free electrons increases when the temperature risesThe electrical resistance of a semiconductor material will decrease as the temperature increasesIonization potential – the potential required to remove a valence electronSilicon – nonmetalGermanium – a semiconductor that is classified as a metalloid or semimetalGermanium – semiconductor that is very rare, it only occurs in minute quantities in many metal sulfidesCompound semiconductors are also known as inter-metallic semiconductorsCompound semiconductor – semiconductor that is mostly used in devices requiring the emission or absorption of lightsFor high-speed integrated circuit, Gallium arsenide semiconductor material is best to be usedOne part per million impurity concentration is needed for a sample of silicon to change its electrical property from a poor conductor to a good conductorThe restriction of certain discrete energy levels in a semiconductor material can be predicted generally by using Bohr modelElectron Volt (eV) – is defined as the energy acquired by an electron moving through a potential of one volt.EHP optical generation is the basis in operation of semiconductor photoconductorsSelenium – the semiconductor that is used in xerographyRecombination - when an electron at the conduction band falls back to the valence band it will recombine with the hole.Germanium semiconductor is mostly used to detect near infrared.Silicon carbide (SiC) semiconductor is good for high-temperature applicationsIndium antimonide semiconductor has the highest mobilityA semiconducting glass is known as amorphous semiconductorFor an electroluminescent of green and red lights, gallium phosphide semiconductor is bestLess than 1 watt – typical range of power dissipation for a semiconductor to be considered as “low power” or small signal”Zinc Sulfide (ZnS) semiconductor material has the highest energy gapInSb semiconductor has the smallest energy gap

Mobility – defined as the average drift velocity of electrons and holes per unit electrostatic field. The ease with which a charge carrier moves in a semiconductor material

InSb semiconductor material has the highest value of electron-mobilityAIP semiconductor material has the slowest electron-mobilityPn junction is formed when n-type and p-type semiconductors are brought togetherPN junction acts as a one way valve for electrons because when electrons are pump from P to N, free electrons and holes are force apart leaving no way for electrons to cross the junctionJunction diode – the device that is formed when an n-type and p-type semiconductors are brought togetherForward bias – an external voltage applied to a junction reduces its barrier and aid current to flow through the junctionDiode – a device containing an anode and a cathode or a pn junction of a semiconductor as the principal elements and provides unidirectional conductionUnidirectional conduction in two-electrodes in any device other than a diode, such that rectification between the grid and cathode of a triode, or asymmetrical conduction between the collector and base of a transistor is called diode actionThe p-type material in a semiconductor junction diode is technically termed as anodeCathode in a semiconductor junction diode is referred to the n-type terminalDepletion region – the area in the semiconductor diode where there are no charge carriers

A junction diode is said to be forward-biased if a voltage greater than threshold is applied, with cathode less positive than anodeReverse saturation current is a very small amount of current that will flow in the diode when it is reverse biasedThreshold voltage – the minimum voltage required before a diode can totally conduct in a forward direction The threshold voltage of the diode will decrease when it operates at higher temperaturesThe forward current in a conducting diode will increase as the operating temperature increases.As the operating temperature of a reverse-biased diode is increased, its leakage or reverse saturation current will increase exponentiallyReverse current – the small value of direct current that flows when a semiconductor device has reverse biasThe breakdown voltage of a junction diode will decrease as operating temperature rises.In every increase of 10 C in the operating temperature of a diode will cause its reverse saturation current to doubleDc resistance – the resistance of the diode when operating at a steady state voltageDynamic resistance – the resistance of the diode that is significant when operating with a small ac signalWhen a diode is used in large ac voltages, the resistance that is to be considered is average resistanceThe diode resistance will decrease when the applied voltage is increasedThe primary use of Zener diode in electronic circuits is a voltage regulatorIn electronics, an avalanche breakdown primarily depends on ionizationWhen a diode is reverse biased the depletion region widens, since it is in between positively charge holes and negatively charge electrons, it will have an effect of a capacitor, this capacitance is called transition capacitanceIn a semiconductor diode, the total capacitance, that is the capacitance between terminals and electrodes, and the internal voltage variable capacitance of the junction is called diode capacitanceDiffusion capacitance or storage capacitance is significant when the diode is forward biasedVaractor and varistor – a diode that is especially designed to operate as a voltage-variable capacitor. It utilizes the junction capacitance of a semiconductor diodeThe capacitance of a varactor will increase when the forward bias voltage is increased.Reverse recovery time – the time taken by the diode to operate in the reverse condition from forward conductionIn operating a diode at high-speed switching circuits, one of the most important parameters to be considered is reverse recovery time.Forward recovery time – the time required for forward voltage or current to reach a specified valued after switching the diode from its reverse-to-forward-biased state.Maximum dissipation power – the maximum power the diode can handleCurrent capacity is the most important specification for semiconductor diode.The power handling capability of a diode will decrease if it is to operated at a higher temperaturePower derating factor – diode parameter that will inform the user as to what factor does the power handling capability of the diode is reduced as the operating temperature is increasedZener diode – a semiconductor device especially fabricated to utilize the avalanche or zener breakdown region. This is normally operated in the reverse-region and its application is mostly for voltage reference or regulationTunnel diode – Refers to a special type of diode which is capable of both amplification and oscillation Avalanche – the effect when the electric field across a semiconductor is strong enough which causes the free electrons to collide with valence electrons, thereby releasing more electrons and a cumulative multiplication of charge carriers occur.Tunnel diode – a negative resistance diode commonly used in microwave oscillators and detectors, it is sometimes used as amplifiers. This device is also known as Esaki diodeGunn diode – diode whose negative resistance depends on a specific form of quantum-mechanical bond structure of the materialOne of the electronic semiconductor devices known as diac, function as two terminal bi-directional switchDiac – another name of a three-layer diode. This is also considered as an ac diode.Point-contact diode – semiconductor diode that have a fine wire whose point is in permanent contact with the surface of a water of semiconductor material such as silicon, germanium or gallium-arsenideWhen the p-n junction of a semiconductor diode is inserted with an intrinsic material, the diode becomes a PiN diodeShockley diode – a four layer semiconductor diode whose characteristic at the first quadrant is similar to that of a silicon controlled rectifier (SCR)

Backward diode – a diode that is especially processed so that its high-current flow takes place when the junction is reverse biased. It is a variation of a tunnel diode.Thyrector – a silicon diode that exhibits a very high resistance in both direction up to certain voltage, beyond which the unit switches to a low-resistance conducting state. It can be viewed as two zener diodes connected back-to-back in series.IMPATT diode – a type of Read diode that uses a heavily doped n-type material as its drift regionDiode pack – a device containing more than one diode. An example is the full-wave bridge-rectifier integrated circuitDiode impedance – is the combination of the inductance of the leads and electrodes, capacitance of the junction, and the resistance of the junction of a semiconductor diodeZener effect – In a reverse-biased pn junction, the sudden large increase in current that occurs when a particular value of reversed voltage is reached, and which is due to ionization by the high intensity electric field in the depletion regionGunn effect – the appearance of RF current oscillations in a dc-biased slab of n-type gallium arsenide in a 3.3 kV electric fieldZener impedance – the impedance presented by a junction operating in its zener breakdown region.Characteristic curve – a curve showing the relationship between the voltage and the current of the diode at any given temperatureLoad line – the line that is plotted in the diode characteristic curve which represent the loadThe magnitude of the load-line slope will increase when the load resistance is decreased.Clipper – diode circuit that is used to cut a portion of the input signalSeries clipper – a clipper circuit wherein the diode is connected in series with the load.Parallel clipper – a clipper circuit wherein the diode is shunted with the loadClamper – a network with a diode an a capacitor that is used to shift the dc-level of the input signalHalf-wave rectifier is a good example of a series clipperClamper must have a capacitor2 resistors are used in a diode-capacitor half-wave voltage doublerDiode array – a combination of several diodes in a single housingDiode chopper – a chopper, employing an alternately biased diode as the switching element.Zener voltage regulator – a simple voltage-regulator whose output is the constant voltage drop developed across a zener diode conducting in the reverse breakdown region. The regular circuit consists of a zener diode in parallel with the load and an appropriate limiting resistorDTL – logic circuitry in which diode is the logic element and a transistor acts as an inverting amplifierHalf-bridge – bridge rectifier having diodes in two arms and resistors in the other two.Crowbar – an over-voltage protection circuit employing a zener diode and a SCR whose function is to produce high overload by-pass current on a circuit.The flow of electron in a NPN transistor when used in electronic circuit is from emitter to collectorTransistor – a three terminal, three layer semiconductor device that has the ability to multiply charge carriers. This device was first introduced at Bell Laboratories, by Brattain and Bardeen in 1947 and which opens a completely new direction of interest and development in the field of electronicsTransistor – an active semiconductor device, capable of amplification, oscillation, and switching action. It is an acronym for transfer reisistor and had replaced the tube in most applications.The base in the region/area in a transistor is the smallest in constructionEmitter – the region or area in a transistor that is heavily dopedAlloy-diffused transistor – a transistor in which the base is diffused and the emitter is alloyed. The collector is provided by the semiconductor substrate into which alloying and diffusion are affected.Alloy transistor – a transistor whose junction are created by alloyingAlloy junction – In a semiconductor device, a p-n junction formed by alloying a suitable material such as indium with the semiconductor.Diffused transistor – a transistor in which one or both electrodes are created by diffusionBipolar transistor – a two-junction transistor whose construction takes the form of a pnp or a npn. Such device uses both electron and hole conduction and is current-drivenPoint-contact transistor – the predecessor of the junction transistor, and is characterized by a current amplification factor, alpha of greater than one.For a transistor, the outer layers are heavily doped semiconductorsThe ratio of the total width of the outer layer to that of the center layer is 150:1The ratio of the doping level of the outer layers to that of the sandwiched material is 10:1 or less

Limiting the number of “free” carriers will decrease the conductivity but increases the resistanceThe term bipolar reflects the fact that holes and electrons participate in the injection process into the oppositely polarized material.Unipolar device employs only electrons or holeAt forward-biased junction of pnp transistor, majority carriers flow heavily from p- to the n-type materialThe minority-current component of a transistor is called leakage currentIco – is temperature sensitive, and can severely affect the stability of the system, when not carefully examined during designFor the transistor, the arrow in the graphic symbol defines the direction of emitter conventional current flow through the deviceIn the dc mode, the levels of Ic and Ie due to the majority carriers are related by the quantity alpha (α)In the ac mode, alpha is formally called common-base, short-circuit, amplification factorPhrases “not pointing in” and “pointing in” simply mean npn and pnpIn the dc mode, the levels of Ic and Ib are related by a quantity called For practical transistor devices, the level of typically ranges mostly in midrange of 50 to 400The formal name of beta is common-emitter forward-current amplification factor – it is a particularly important parameter that provides a direct link between current levels of the input and output circuits for a common-emitter configurationThe cutoff region is defined as the area below Ic = IceoWith an ohmmeter, a large or small resistance in either junction of an npn or pnp transistor indicates faulty deviceAt base-emitter junction, using an ohmmeter, if the positive lead is connected to the base and the negative lead to the emitter, a low resistance reading would indicate npn transistorAt base-emitter junction, if the positive lead is connected to the base and the negative lead to the emitter, a high resistance reading would indicate pnp transistorHigh-power devices – transistors of heavy duty constructionSaturation point – on a voltage-current condition curve, the point belong to which a further increase in voltage produces no further increase in current.Saturation – it is applied to any system where levels have reached their maximum valuesFor an “on” transistor, the voltage Vbe should be in the neighborhood of 0.7 VActive region in a transistor amplifier is normally employed for linear amplifiersIn the active region, the collector-base junction is reverse, while the base-emitter junction is forward-biasedDc biasing is necessary, in order to establish the proper region of operation for ac amplificationAt cutoff region, the collector-base and base-emitter junctions of a transistor are both reverse-biasedIn saturation region, the collector-base and base-emitter junctions of a transistor are both forward-biasedIf the base-emitter junction is reverse biased and the base-collector junction is forward biased, the transistor will be at cut-off regionTransistor operate at cut-off region if both the base-emitter and base-collector junctions are reverse-biasedThe transistor should be operating at active region to have minimum distortion at the output signalQuiescent – In dc biasing, it means quiet, still, inactiveEmitter – the transistor terminal that handles most currentStability factor indicates the degree of change in operating-point due to temperature variation in the dc biasingCut-off current flows between the collector and emitter terminals when the base is openWhen the transistor is saturated, Vce is approximately 0 VCollector-emitter resistance of ideal transistor at cut-off is InfiniteIcbo – the leakage current that flows at the collector-base junction when the emitter is openReverse saturation current – the most correct technical term of the reverse leakage current that flows between the collector and base junctions when the emitter is open circuitIcbo of an ideal transistor is zero mAThe maximum voltage that can be applied across the collector-emitter terminal for a given transistor is specified as VceoWhen base is common to both the input and output sides of the configuration and is usually the terminal closest to, or at ground potential, it is called common-base terminologyCommon collector transistor configuration has the highest input resistanceLower input resistance characteristic refers to that of a common-base (C-B) as compared to common-emitter (C-E) and common-collector (C-C) amplifiers

A transistor is said to be configured as common emitter if the emitter terminal is not used as an input nor outputMost frequently used transistor configuration for pnp and npn is common-emitterCommon-emitter configuration hybrid parameters is usually specified by the manufacturersHr and ho – hybrid parameter that is usually neglected in circuit analysisIn most transistor input equivalent circuit it comprises of a resistor and a voltage sourceCommon-collector configuration has the highest input resistanceCommon-base configuration has a high voltage gain and a current gain of approximately equal to oneCommon-emitter configuration has the highest power gainCommon-collector configuration has the highest power gainOutput characteristic curve is most usefulMaximum power curve – the graph of the product of collector-emitter voltage Vce and collector current Ic in the transistor output characteristic curveThe base of a transistor serves as a gate element of the FETBJT is current-controlled device; FET is voltage-controlled deviceAnother difference between a BJT and a FET with regards to its normal biasing, is that the input circuit is forward-biased for BJT while reverse for FETDue to the reverse-biased input circuit of FETs, FET offer high input impedance then BJTThe operation of BJT involves both the flow of electrons and holes and is therefore, considered as a bipolar device. Unlike BJT, FET’s operation involves only either electrons of holes and is considered as a unipolar deviceConsidered as the basic FET or the simplest form of FET is the JFETS-G-D JFET : E-B-C BJTOne obvious advantage of a JFET over BJT is its high input resistanceA BJT is a current-controlled current-source device while JFET is a voltage-controlled current source deviceChannel – the area in a JFET where current passes as if flows from source to drainThe channel of a JFET will skews as current flows to it.For a normal operation of an n-channel JFET, you bias the gate-source junction by negative-positive respectivelyPinch-off voltage – the voltage across the gate-source terminal of a FET that causes drain current Id equal to zeroDrain-source saturation current – the current that flows into the channel of a JFET when the gate-source voltage is zeroCurrent-voltage characteristic curve – the graph of the drain current Id versus drain-source voltage Vds with Vgs as the parameterFieldistor – an early version of the field effect transistor in which limited control of current carriers near the surface of a semiconductor bar or film was obtained by an external electric field applied transverselyJFET – A FET in which the gate electrode consists of a pn junctionJFET has the lowest input resistanceIn order to increase further the input resistance of a FET, its gate is insulated. An example of this type is the MOS-FETSiO2 is the insulator used in most MOS-FETSubstrate – In MOSFET, it is the foundation upon which the device will be constructed and is formed from a silicon baseEnhancement type – a type of MOSFET wherein originally there is no channel between the drain and the sourceDepletion type of MOSFET whose channel is originally thick but narrows as the proper gate bias is appliedThreshold voltage – the amount of voltage needed at the gate-source terminal for an enhancement type MOSFET so that a channel can be formed for the current to flowTo switch off the depletion type MOSFET, the channel should be depleted. Depletion of the channel is done by applying enough voltage across the gate-source terminal. This voltage is called pin-off voltageThe substrate of a MOSFET is usually connected internally to sourceIn an n-channel enhancement type MOSFET, the gate voltage should be positive with respect to the source in order to produce or enhance a channelTo deplete a channel from a p-channel IGFET depletion type, the gate voltage should be positive with respect to the source.N –type material - The substrate used in a p-channel IGFET enhancement typeSubstrate (SS) – the base material of a MOSFET which extends as an additional terminalMOSFET enhancement type operates as close as BJT in terms of switchingGenerally, MOSFET has low power handling capability than BJT. To increase MOSFET power, the channel should be made wide and shortV-MOSFET has a wide and short effective channelV-MOSFET – a type of FET wherein the channel is formed in the vertical direction rather than horizontalIn general, FETs is particularly more useful in integrated-circuit (IC) chips

FET – a monolithic semiconductor-amplifying device in which a high-impedance GATE electrode controls the flow of current carriers through a thin bar of semiconductor called the CHANNEL. Ohmic connections made to the ends of the channel constitute SOURCE and DRAIN electrodesSolid State Devices / CircuitsVaractor diodes are commonly used as a voltage controlled capacitanceThe electrons in the largest orbit travel more slowly than the electrons in the smaller orbitsCommon base – a transistor configuration with the lowest current gainA semiconductor in its purest form is called intrinsic semiconductorValence orbit is the other term for outer orbitFor either germanium or silicon diodes, the barrier potential decreases 2 mV for each Celsius degree risePiecewise linear model – a diode modeling circuit which considers, the threshold voltage, average resistance and switch as the diode’s equivalent circuitDiffusion and drift – two mechanisms by which holes and electrons move through a silicon crystal A semiconductor is an element with a valence of fourValence orbit controls the electrical properties of the atomConductor is a substance that contains atom with several bands of electrons but with only one valence electronPure silicon contains 8 valence electrons as a result of covalent bondingThe peak inverse voltage of a full wave center tapped rectifier circuit is equal to twice the peak of the input signalDiffusion or storage capacitance is the term used to refer to the forward bias capacitance of a diodeThe number of electrons in the valence orbit is considered as the key to electrical conductivityEach atom in a silicon crystal has 8 electrons in its valence orbitLifetime is the amount of time between the creation and disappearance of a/an free electronA silicon crystal is intrinsic semiconductor if every atom in the crystal is a silicon atomAt room temperature, a silicon crystal acts approximately like an insulatorAn extrinsic semiconductor is a doped semiconductorDiffusion is associated with random motion due to thermal agitation in the movement of holes and electrons in a silicon crystalThe peak inverse voltage of a half wave rectifier circuit is approximately equal to the peak amplitude of the input signalSilicon that has been doped with a trivalent impurity is called a p-type semiconductorSilicon that has been doped with a pentavalent impurity is called a n-type semiconductorJunction diode is another name for a pn crystalAn acceptor atom is also called trivalent atomPentavalent atom – donor atomIn an n-type semiconductor, free electrons are called majority carriersIn an n-type semiconductor, holes are called minority carriersEach pair of positive and negative ions at the junction is called a dipoleWhen temperature increases, barrier potential decreasesAvalanche effects occurs at higher reverse voltagesThe creation of free electrons through zener effect is also known as high-field emissionZener effect depends only on the intensity of the electric fieldJunction temperature is the temperature inside the diode, right at the junction of the p and n-type materialsGate voltage is the input parameter of a FETForward current – one of the important diode parameter which gives the magnitude of current the diode can handle without burningThe maximum reverse voltage that can be applied before current surges is called reverse breakdown voltageTunnel diode – another name for Esaki diodeThe most important application of Schottky diode is in digital computersA diode is a nonlinear device because its current is not directly proportional to its voltageThe sum of the resistances of the p-region and the n-region is called bulk resistanceThe typical bulk resistance of rectifier diode is less than 1 ohmThe reverse bias diode capacitance is termed as transition region capacitanceReverse recovery time – the time taken by the diode to operate in the reverse condition from forward conductionApproximately, the atomic weight of germanium is 72.6Atomic weight of silicon at 300K is 28.09An LED and a phototransistor is equivalent to an OptocouplerOptocoupler is otherwise known as Optoisolator

When the emitter junction is forward biased while the collector junction is reverse biased, the transistor is at active regionWhen both the emitter and collector junction are forward biased, the transistor is said to be at saturation regionSecond approximation – An equivalent circuit of a diode in which it is represented as a switch in series with a barrier potentialThird approximation – an equivalent circuit of a diode in which it is represented as a switch with a battery in series with a resistanceA silicon crystal is an intrinsic of semiconductor if every atom in the crystal is a silicon atomWith npn voltage divider bias, you must use negative power supplyA half-wave signal has a period of 16.7 msA full-wave signal has a period of 8.3 msWhen doping increases, bulk resistance of a semiconductor decreasesFET has the least noise levelMOSFET has the highest input impedanceThe frequency of a half-wave signal is equal to the line frequencyFor a full-wave rectifier, the output frequency equals two times the input frequencyThe average dc voltage of a half wave rectifier circuit is 31.8% of the value of the peak input voltageThe average dc voltage of a full wave rectifier circuit is 63.6% of the value of the peak input voltageTypical leakage current in a pn junction is in the order of μAThe resistance of a forward biased pn junction is in the order of ohmThe removal by electronic means of one extremity of an input waveform is called clippingShockley diode – a type of diode with no depletion layerVaristor are used for line filtering to eliminate spikes and dips and is also called transient suppressorDiffusion – Defined as the random motion of holes and free electrons due to thermal agitationThe temperature coefficient of resistance of a semiconductor is negativeClass A – a large signal amplifier which is biased so that collector current flow continuously during the complete electrical cycle of the signal as well as when no signal is presentClass C – a large signal amplifier which is biased so that current is non-zero for less than one-half cycleA class AB amplifier stage operates with a small forward bias on the transistor so that some collector current flow at all timesDerating factor – A factor shown on a data sheet that tells how much you have to reduce the power rating of a deviceThe time it takes to turn off a forward-biased diode is called the reverse recovery timeA heavily doped semiconductor has low resistanceGallium arsenide, aluminum arsenide and gallium phosphide are classified as compound semiconductorA lightly doped semiconductor has high resistanceConductance – the property or ability of a material to support charge flow or electron flowDember effect – also known as photodiffusion effectBulk effect – an effect that occurs within the entire bulk of a semiconductor material rather than in a localized region or junctionDember effect – the creation of a voltage in a conductor or semiconductor by illumination of one surface.Point-contact diode uses a metal catwhisker as its anode and is classified as a hot-carrier diode10 mA is the typical operating current of an LEDAt absolute zero temperature, a semiconductor behaves as a/an insulatorAvalance breakdown in a semiconductor take place when reverse bias exceeds a certain valueAnotron – a cold-cathode glow-discharge diode having a copper anode and a large cathode of sodium or other materialBARITT diode – A microwave diode in which the carriers that transverse the drift region are generated by minority carrier injection from a forward-biased junction instead of being extracted from the plasma of an avalanche regionA voltage multiplier is an electric circuit that converts AC to DC but where the DC output peak value can be greater than the AC input peak valueThe charge of a hole is equal to that of a proton – it is the current gain for the common-emitter configurationAn emitter resistor is used for biasing a bipolar junction transistor in most amplifier circuitsLoad line is a line drawn between the open-circuit voltage and the short-circuit current on a JFET characteristic curveAnother name for a photoconductive cell is photoresistive device

When both the emitter and collector junctions are reverse biased, the transistor is said to be at cut-off regionVaractor diode – a type of diode used for tuning receivers and is normally operated with reverse bias and derived its name from voltage variable capacitorBinistor – A silicon npn tetrode that serves as a bistable negative-resistance deviceSpacistor – a multiple-terminal solid-state device similar to a transistor that generates frequencies up to about 10,000 MHz by injecting electrons or holes into a space-charge layer which rapidly forces these carriers to a collecting electrode.Silicon is not a good conductor1.5 V is the approximate voltage drop of LEDUnder standard condition, pure germanium has a resistitivity of 60 ohm-cmThe holding of one extreme amplitude of the input waveform to a certain amount of potential is called clampingClamper is also known as DC restorerPercentage ripple can be calculated by getting the ratio of the ac voltage to dc voltage and multiplying the result by 100%Silicon has the smallest leakage currentRecombination refers to annihilation of a hole and electronZener and avalanche effects are the two possible breakdown mechanism in pn junction diodesZener breakdown occurs in pn diodes when the electric field in the depletion layer increases to the point where it can break covalent bonds and generate electron hole pairsThe amount of additional energy required to emit an electron from the surface of a metal is called work functionWhen the temperature of a pure semiconductor is increased, its resistances decrease.As a general rule, holes are found only in semiconductorsHole in a semiconductor is defined as the incomplete part of an electron pair bondWhen the number of free electrons is increased in doped semiconductor, it becomes a n type semiconductorReducing the number of free electrons in a doped semiconductor forms a p type semiconductorPure semiconductor atoms contain 4 valence electronsAn acceptor atom contains 3 valence electronsThe resistivity of an extrinsic semiconductor is 2 ohm-cmThe forward resistance of a crystal diode is in the order of ohm1 is the ideal value of stability factor1.6726 x 10^-27 kg is the approximate mass of an atom at restApproximate mass at rest of a proton is equal to that of a neutronCharge of an electron is approximately equal to -1.6022 x 10^-19 CElectrolytic capacitors are used in transistor amplifiersThe reason why a common collector is used for impedance matching is because its input impedance is very highIn power supplies, circuits that are employed in separating the ac and dc components and bypass the ac components around the load, or prevent their generation are called series capacitorsIsotopes – nuclei with common number of protons, but with different number of neutronsFET has a high input impedance because its input is reverse biasedA MOSFET is sometimes called insulated gate FETAn advantage of a MOSFET over a BJT in an RF amplifier circuit is low noiseThe voltage gain of an emitter follower circuit is lowA transistor is considered a current controlled deviceA FET is considered a voltage controlled deviceThe value of coupling capacitor, Cc n RC coupling is about 10 μFFET has a pinch-off voltage of about 5 VLuminous efficacy – a measure of the ability of an LED to produce the desired number of lumens generated per applied watt of electrical energyPhotoconductive effect means the increased conductivity of an illuminated semiconductor junctionWhen light strikes on a photoconductive material the conductivity of the material increasesVaractor diode – a type of diode used for tuning receivers; operate with reverse bias and derived its name from voltage-variable capacitorGallium arsenide semiconductor material is used in the construction of LEDAtomic mass is approximately the sum of the number of protons and neutrons of an atomAtomic number is the number of protons in the nucleus or the number of electrons in an atom The charge of a proton has the same value to that of an electron but opposite in signMass of proton or neutron is 1,836 times that of an electronLAD – a photodiode which conducts current only when forward biased and is exposed to light

Red is the most commonly used color for an LEDIf the temperature of a semiconductor material increases, the number of free electrons increasesVaractor diode’s transition capacitance is directly proportional to the product of the permittivity of the semiconductor material and the PN junction area but inversely proportional to its depletion widthA photodiode is a light-sensitive device whose number of free electrons generated is proportional to the intensity of the incident light.Scale current – another name for saturation current in a diode, which arises from the fact that it is directly proportional to the cross-sectional area of the diodeIn an amplifier, the emitter junction is forward biasedThe principal characteristic of a zener diode is the constant voltage under conditions of varying currentVaractor diode – a device whose internal capacitance varies with the applied voltageThe common collector transistor configuration has the highest value of input resistanceCoupling – the method of connecting amplifier in cascadeCollector is the largest region of a bipolar transistorTunnel diode – A diode that has a negative resistance region and widely used in the design of oscillators, switching networks and pulse generators.Diac – refers to a three layer diodeZener diode – diode that operates in the reverse breakdown voltage and is used as a voltage regulatorIGFET – Another name for a metal-oxide semiconductor field effect transistorIn enhancement-type MOSFET, the saturation region is used if the FET is to operate as an amplifierIn enhancement-type MOSFET, the triode and saturation regions are used for operation as a switchUnijunction transistor has three terminals, namely base 1, base 2 and emitterSilicon and germanium semiconductor devices exhibit both metallic and nonmetallic characteristicsThe voltage drop across the diode remains relatively constant when current flow increases rapidly in a forward-biased diodeFree electrons are the majority current carriers in the N-type silicon A LED is a diode that gives off light when energizedIR emitters – are solid state gallium arsenide devices that emit a beam of radiant flux when forward biasedInput characteristic curve – a graphical representation in transistor wherein the emitter current is plotted against the variable emitter base voltage Veb for constant value of collector-base voltage VcbWhen the collector current Ic is plotted against the collector base voltage at constant emitter current Ie, the curve obtained is called output characteristic curveEg for silicon is 1.12 eV and for germanium is .072 eV. It can be concluded that less number of electron hole pairs will be generated in silicon than in germanium at room temperatureJunction diodes are commonly rated by its maximum forward current and PIVA special type of diode which is often used in RF switches, attenuators, and various types of phase shifting device is called PIN diodeOutput characteristic – A volt-ampere characteristics curve that describes the relationship of the output voltage of a transistor to its output current at a set input currentThe use of RC coupling is particularly desirable in low level, low noise audio amplifier stages to minimize hum pick up from stray magnetic fieldsThe way in which the gain of an amplifier varies with the frequency is called frequency responseThe maximum rectification efficiency of a half wave rectifier is 40.6 %The maximum rectification efficiency of a full-wave rectifier is 81.2 %Transformer coupling – a coupled amplifier which has the major advantage of permitting power to be transformed from the relatively high output impedance of the first stage to the relatively low input impedance of the second stageElectron mobility property of silicon at 300 K is approximately equal to 0.135 m^2/v-sIn a push-pull power amplifier, an input transformer can be used as a phase-splitter providing equal amplitude input signals opposite in polarityIf the line frequency is 60Hz, the output frequency of a bridge rectifier is 120 HzFET is considered a unipolar deviceHarold Black – invented the feedback amplifier in 1928The arrow in semiconductor symbols always point toward the N region and away from the P regionIf the input power of a half wave rectifier has a frequency of 400 Hz, then the ripple frequency will be equal to 400 HzIf the input frequency of a full-wave rectifier is 400 Hz, the ripple frequency will be twice as great as the input frequencyCommon emitter circuit – also called as the conventional amplifier

Another name for a light activated diode (LAD) is photodiodeThe semiconductor device that radiate light or utilize light are called optoelectronic devicesStructural category of a semiconductor diodes can be either junction and point contactZener diodes can be primarily classified as voltage regulation and voltage referenceThe principal characteristic of a tunnel diode is a negative resistance regionVaractor diode – a special type of semiconductor diode which varies its internal capacitance as the voltage applied to its terminal variesThe maximum forward current in a junction diode is limited by its junction temperatureWhen a transistor is fully saturated the collector current is at its maximum valueA FET without a channel and no current occurs with zero gate voltage is enhancement-mode FETFET and CMOS devices are susceptible to damage from static chargesJFETs are often called square law devicesEquivalent of transistor at saturation in JFET’s is constant-currentWhen a JFET is cut-off, the depletion layers are touchingThe voltage that turns on an enhancement-mode device is the threshold voltageDepletion-mode MOSFET acts mostly as a JFETJFET’s input impedance approaches infinityThe current gain of an emitter follower circuit is highThe drift transistor has a high frequency cut off due to its low inherent internal capacitance and low electron transit time through the baseThe maximum operating frequency of a transistor should be 50 percent of the frequency cut-off of the transistor to ensure best performanceWhen transistor applications call for a temperature operating condition which exceeds 185 F, Silicon element is most suitableHeat dissipation is the most important factor of a power transistorWhen the electron transmit time through the base region is very short, this provides higher cut-off frequencyWhen the transistors are used in video amplifiers, its main limitation is poor frequency responseImpedance matching in circuit is important for maximum transfer of energyA unijunction transistor is a three-terminal device consisting of two semiconductor layersIonization – the process by which atoms are constantly losing and regaining free electronsParasitic oscillations – termed as unwanted oscillation that may occur in almost any type of circuits, oscillator, amplifier, power supply, receiver and transmitters.Linear amplifier – an RF amplifier which will amplify a weak signal voltage in relatively the same proportion as it will amplify a stronger signal voltagePeak inverse voltage – it is the maximum amount of reverse voltage which can be applied on a diode before the breakdown point is reachedElement – it refers to any of the over 100 different substances which have never been separated into simpler substances by chemical means and which alone or in combination constitute all matterLED – it is also known as a solid state lamp which utilizes the fall of electron from the conduction level to the valence level to develop an energy release in the form of heat or lightPresent atomic theories place the mass and positive charge of an atom in a central nucleus composed of protons and neutronsThe photons as fundamental particle is considered as a bundle of radiant energy or light, the amount of energy being related to the frequencyElectron emitted by the mechanical impact of an iron striking a surface is called secondary electronsThe break up of nuclei into nuclear fragments that are themselves nuclei is called fissionNeutrinos - Particles of zero charge and zero mass9.1096 x 10^-31 kg – approximate mass of an electron at restValence shell – term used to describe the outermost shell of an atom Free electrons – are the electrons at the outermost shell which are usually weakly attracted by the core such that an outside force can easily dislodge these electrons from the atomThe reason why electrons are not pulled in the positive charged nucleus is because of the centrifugal force which usually became exactly equals the inward attraction of the nucleusValence band – the highest energy band of an atom which can be filled with electronsConduction band – an energy band in which electrons can move freelyGold is considered as the best conductorCrystal – it is an arrangement of silicon atom combine to form a solid such that there are now 8 electrons in the valence shell

Covalent bond – the sharing of valence electrons to produce a chemically stable atomBound electrons – the eight electrons which are tightly held by the atomWhen an atom has bound electrons, it is described as filled or saturated since valence orbit can hold not more than 8 electronsAmbient temperature – refers to the temperature of the surrounding airFree electrons – the term used to describe the released electrons dislodged form its original shell due to increase in temperature which joins into a larger orbitHole – the term used to refer to the vacancy left by the free electron when it departs from its original shellRecombination – the merging of a free electron and a hole inside the silicon crystalLifetime – the amount of time between the creation and disappearance of a free electronThe purpose of adding an impurity atom to an intrinsic crystal is to increase its electric conductivityAn extrinsic semiconductor produced n-type when a pentavalent atom are added to the molten siliconPhosphorus, antimony and arsenic are pentavalent atomP-type – an extrinsic semiconductor which is produced when a trivalent atom are added to the molten siliconLinear power derating factor – the reduction of power handling capability of the diode due to the increase of ambient temperature form room temperatureMaximum junction temperature – the maximum temperature the diode can operate before burningReverse recovery time of the diode is computed as the sum of the storage time and transition interval from the forward to reverse biasThermal energy causes intrinsic semiconductor to have some holesWhen a diode is forward biased, the recombination of free electrons and hole may produce heat, light & radiationPhosphorous doping element has a valence of 5Silicon doping element has a valence of 4Boron doping element has a valence of 3Proton – it is a stable positive charge in the nucleus that is not free to move.Hole – a positive charge outside the nucleus which is present only in semiconductor due to unfilled covalent bondsWhen charges are forced to move by the electric field of a potential difference, drift current is said to flowWhen a PN junction is connected to a battery in such a way that P-side is connected to positive terminal of the battery and negative terminal to N-side, this connection is known as forward biasWhen a PN junction is connected to a battery in such a way that P-side is connected to negative terminal of the battery and positive terminal to N-side, this connection is known as reverse biasAn electron in the conduction band has higher energy then the electron in the valence bandAn ideal diode should have zero resistance in the forward bias and an infinitely large resistance in reverse biasThermal voltage is approximately equal to 25 mV at room temperatureBoltzmann’s constant is equivalent to 8.62 x 10^-5 eV/KThe preferred form of biasing a JFET amplifier is through the self biasThe gate-to-source on voltage of an n-channel enhancement mode MOSFET is greater then VgsCarrier drift – a mechanism for carrier motion in semiconductors which occurs when an electric field is applied across a piece of siliconAvalanche breakdown occurs in pn diodes when the minority carriers that cross the depletion region under the influence of the electric field, gain sufficient kinetic energy to be able to break covalent bonds in atoms with which they collide

ELECTRONIC CIRCUITS

Class A amplifier has an output current flowing during the whole input current cycle.

If a transistor amplifier provides a 360 output signal, it is classified as class A

Class B – an amplifier that delivers an output signal of 180 only

Class AB – a class of amplifiers wherein the output signal swings more than 180 but less than 360

The distinguishing feature of class C amplifier is that the output is present for less than 180 degrees of the input signal cycle

Class C – a full 360 sine-wave signal is applied as an input to an unknown class of amplifier, if the output delivers only a pulse of less than 180

Class D amplifiers are intended for pulse operation

Class S amplifier are used to amplify either amplitude modulated (AM) or frequency modulated (PM) signal

Class D amplifier has the highest efficiency

25% is the efficiency of a series-fed class A amplifier

A class A amplifier has an efficiency of only 25%, but this can be increased if the output is coupled with a transformer. Up to 50% efficiency will be reached due to coupling

Class B amplifiers deliver an output signal of 180 and have a maximum efficiency of 78.5%

Transistorized class C power amplifier will usually have an efficiency of 33%

For pulse-amplification, class D amplifier is mostly used. Class D amplifier efficiency reaches over 90%

Efficiency of class AB is in between the efficiency of class A and B, that is from 25% - 78.5%

Class A (transformer-coupled) is the most effient

In order to have the best efficiency and stability, the loadline of a solid state power amplifier be operated just below the saturation point

In most transistor class A amplifier, the quiescent point is set at the centerFor a class B amplifier, the operating point or Q-point is set at cutoff

The Q-point for class A amplifier is at the active region, for class B it is at cutoff region, while for class AB is slightly above cutoff

The Q-point of a class C amplifier is positioned below cutoff region

Class C amplifiers are considered as non-linear

Class A or B amplifiers can be used for linear amplification

Class BC amplifier is biased to class C but modulates over the same portion of the curve as if it ware biased to class B

Transformer-coupled push-pull amplifier – two class B amplifiers connected such that one amplifies the positive cycle and the other amplifies the remaining negative cycle. Both output signals are then coupled by a transformer to the load

Complementary-symmetry amplifier – a push-pull amplifier that uses npn and pnp transistors to amplify the positive and negative cycles respectively

Quasi-complementary push-pull amplifier – a push pull amplifier that uses either npn or pnp as its final stage. The circuit configuration looks like the complementary-symmetry

Class A amplifier has the least distortion

Nonlinear distortion – a type of distortion wherein the output signal does not have the desired linear relation to the input

Amplitude distortion – Distortion that is due to the inability of an amplifier to amplify equally well all the frequencies present at the input signal

Harmonic distortion – a nonlinear distortion in which the output consists of undesired harmonic frequencies of the input signal

The overall gain of an amplifier in cascade is the product

Cascaded amplifier – a multistage transistor amplifier arranged in a conventional series manner, the output of one stage is forward-coupled to the next stage

Darlington configuration – a direct-coupled two-stage transistor configuration wherein the output of the first transistor is directly coupled and amplified by the second transistor. This configuration gives a very high current gain

Cascode configuration – a two-stage transistor amplifier in which the output collector of the first stage provides input to the emitter of the second stage. The final output is then taken from the collector of the second stage

Cascode amplifier – famous transistor amplifier configuration designed to eliminate the so called Miller effect

Common-emitter and common-base transistor configuration is used in a cascode amplifier

Darlington – transistor configuration known to have a super-beta

1.6 V is the approximate threshold voltage between the base-emitter junction of a silicon darlington transistor

Feedback pair – transistor arrangement that operates like a darlington but uses a combination of pnp and npn transistors instead of both npn

Differential amplifier – an amplifier basically constructed from two transistor and whose output is proportional to the difference between the voltages applied to its two inputs

Operational amplifier (op-amp) – an amplifier having high direct-current stability and high immunity to oscillation, this is initially used to perform analog-computer functions such as summing and integrating.

Op-amp – one of the most versatile and widely used electronic device in linear applications

Op-amp – it is a very high-gain differential amplifier with very high input impedance and very low output impedance

An operational amplifier must have at least 5 usable terminals

Differential amplifier – the circuit at the input stage of operational amplifiers

Differential amplifier – an amplifier whose output is proportional to the difference between the voltages applied to its two inputs

In op-amps functional block diagram, high gain amplifier follows the differential amplifier

A good op-amp has a very high input resistance

Ideally, op-amps have infinite input resistance and zero output resistance

The input of an op-amp is made high by using super beta transistor at the input differential stage or by using FETs at the input differential stage

Complementary amplifier is commonly used at the output stage of op-amps

Common collector – the transistor configuration used at the output complementary stage of most op-amps

Most op-amps use a common collector at the output stage to have a very low output resistance

Level shifter – the stage followed by the output complementary in op amps functional block diagram

The purpose of level shifter in op-amps is to set and/or adjust the output voltage to zero when the input signal is zero

Primarily, op-amps are operated with bipolar power supply, however, we can also use single polarity power supply by generating a reference voltage above ground

When the same signal is applied to both inverting and non-inverting input terminals of an ideal op-amp, the output voltage would be zero V

Common mode – the operating mode of an op-amp, when both inputs are tied together or when the input signal is common to both inputs

Common gain – the gain of an op-amp if operated in common mode inputWhen one input of the op-amp is connected to ground and the other is to the signal source, its operation is called single-ended input

If op-amps are operated in differential mode, its gain is technically termed as differential gain

Open-loop gain is the highest

Common-mode rejection ratio – the ratio of the differential gain and common gain of an op-amp

+VSAT to –VSAT is the maximum output voltage swing of an op-amp

Input bias current - the current needed at the input of an op-amp to operate it normally

Ideal op-amp requires no input current, but real op-amp needs a very small input current called input bias current. At both inputs, the bias currents have a slight difference. Its difference is called input offset current

Input offset current drift – the change in input offset current due to temperature change

The reason why a slight difference between the input bias current occurs in op-amp is due to the unsymmetrical circuit component parameters. This unsymmetrical condition also produces a difference in input voltage called input offset voltage

In op-amps, input offset voltage drift is the change in input offset voltage due to the change in temperature

Ideally, the output voltage of an op-amp is zero when there is no input signal, however, in practical circuit, a small output voltage appears, this voltage is known as output offset voltage

The output offset voltage of an op-amp are due to input offset current and input offset voltage

You minimize the output offset voltage due to the input offset current of an op-amp by installing a bias-current-compensating resistor

The approximate value of the bias-current compensating resistor in op-amp circuit is equal to the parallel combination of the input and feedback resistors

In op-amp analysis, the input offset voltage is represented by a battery

The battery representing the input offset voltage in op-amp circuit analysis is connected between the non-inverting and ground terminal

The effect of the input offset voltage to the output voltage if the op-amp has no feedback element is it causes the output to saturate either towards positive or negative

By making the feedback resistance small we can minimize the effect of the input offset current and input offset voltage at the output offset voltage

The most effective way of minimizing the output offset voltage of an op-mp is by properly using and adjusting the offset-null terminals

Slew rate – op-amp parameter(s) that is important in large signal dc amplification

In large signal dc-amplifiers using op-amp, drift parameter has the least effect on its performance

For ac-amplifiers using op-amps, slew rate and frequency response parameters can affect its performance

If an op-amp is used to amplify small ac-signals, frequency response parameter should greatly consider to ensure better performance

Internally compensated op-amps – op-amps with internal frequency compensation capacitor to prevent oscillation

Break frequency – the frequency at which the open-loop gain of an op-amp is 0.707 times its value at very low frequency

The voltage gain of op-amp will decrease when its operating frequency is increased

Roll-off – the reduction of op-amps gain due to increase operating frequency

20dB/decade roll-off – a gain reduction by a factor of 10 per decade

6 dB/octave – a reduction of op-amp’s voltage gain by a factor of two each time the frequency doubles

Unity-gain bandwidth product – frequency at which the voltage gain of op-amp reduces to unity.

Rise time is defined as the time required for the output voltage to rise from 10% to 90% of its final value

Slew rate – the maximum output voltage rate of change of an op-amp

Factors or parameters that determine the op-amps maximum operating temperature: slew rate and unity-gain bandwidth product

When an op-amp is used as a comparator, the output voltage would be +VSAT if V+ > V-

Window comparator – two comparators using op-amps, configured such that it can detect voltage levels within a certain range of values rather than simply comparing whether a voltage is above or below a certain reference

Open-loop gain is significant when an op-amp is used as a voltage comparator

An op-amp zero-crossing detector without hysteresis, has no feed back

The feed back element of a differentiator constructed from op-amp is a resistor

An active integrator uses an op-amp, capacitor is its feedback element

Unity – the voltage gain of an op-amp voltage follower

The noise gain of op-amps is 1 + Rf/Ri

Making both the feedback and input resistances as small as possible resistor combination provides lesser noise in op-amp circuits

In most ac-amplifiers using op-amps, the feedback resistor is shunted with a very small capacitance to minimize high frequency noise

Externally compensated op-amps are op-amps with frequency-compensation terminals or op-amps with provision to externally compensate for frequency stability

In the external frequency-compensation capacitor, the lower its value, the wider is its bandwidth

Typical value of the external frequency-compensating capacitor of op-amps is about 3.0 – 30 μF

General purpose op-amps are op-amps with limited unity-gain bandwidth up to approximately 1 MHz or op-amps with slew rate about 0.5V/μsecHigh-frequency, high-slew rate op-amps – Op-amps designed to operate at high slew rate, about 2000 V/micosec and at high frequencies, more than 50 MHz

Generally, hybrid op-amps found its application for high-output voltage and for high-output current

0.2 mV – the magnitude of the op-amps input offset voltage before it can be classified as a low-input offset voltage op-amp

Op-amps whose internal transistor biasing can be controlled externally are categorize as programmable op-amps

Metal can correspond to TO-99

Dual-in-line or DIL package is designed as TO-116

SMT – for high density ICs involving many op-amps

PLCCs, SOICs, LCCCs are examples of surface-mounted technology (SMT) device

For a circuit to oscillate, it must have a positive feedback sufficient to overcome losses.

Oscillator – Circuits that produces alternating or pulsating current or voltage

Hartley oscillator circuit uses a tapped coil in the tuned circuit

The size and thickness of the crystal material determines the resonant frequency of a crystal

Relaxation oscillator – type of oscillator whose frequency is dependent on the charge and discharge of RC network

Klystron oscillator – a microwave oscillator

Colpitts oscillator – a self-excited oscillator in which the tank is divided into input and feedback portions by a capacitive voltage divider

Hartley oscillator – A self-excited oscillator in which the tank is divided into input and feedback portions by an inductive voltage divider or a tapped coil

Multivibrator – a circuit usually containing two transistors or tubes in an RC-coulped amplifier, the two active devices switch each other alternately on and off

Monostable – a multivibrator that generates one output pulse for each input trigger pulse

Monostable mutlivibrator is also known as one shot or single shot

Resistor and capacitor combinations determines the pulse time in a monostable multivibrator

Bistable – a multivibrator having two stable state

Bistable multivibrator is also known as Eccles/Jordan circuit

Flip-flop is actually a bistable multivibrator

Astable – considered as a free-running multivibrator

Electronic (Audio/RF) Circuit / Analysis/ Design

Class A and B are considered linear amplifier

The voltage gain of a common collector configuration is unity

A two-transistor class B power amplifier is commonly called push-pull amplifier

If a transistor is operated in such a way that output current flows for 160 of the input signal, then it is Class C operation

Direct coupling has the best frequency response

A transistor amplifier has high output impedance because collector has reverse bias

Gain-bandwidth product is considered an amplifier figure of merit

Logic probe – a piece of equipment in an oscilloscope use to indicate pulse condition in a digital logic circuit

Comparator – a linear circuit that compares two input signals and provides a digital level output depending on the relationship of the input signals

Transformer coupling is generally used in power amplifiers

Class A amplifier’s output current flows for the entire cycle

The coupling capacitor must be large enough to prevent attenuation of low frequency in an RC coupling scheme

Operating point is the point of intersection of dc and ac load lines

An oscillator produces undamped oscillations

Quiescent point is the operating point in the characteristic curve

Oscillators operate on the principle of positive feedback

In a class A amplifier, the output signal is the same as the input

Biasing condition will change if the input capacitor of a transistor amplifier is short-circuited

Biasing is used to establish a fixed level of current or voltage in a transistor

Class C power amplifier has the highest collector efficiency

Class C is a non-linear type of amplifier

An AF transformer is shielded to prevent induction due to stray magnetic fields

Amplitude distortion is otherwise known as harmonic distortion

Hie represents common-emitter small signal input resistance

The ear is not sensitive to frequency distortion

Class C is an amplifier whose output current flow for less than one-half the entire input cycle

If gain without feedback and feedback factor are A and Beta respectively, then gain with negative feedback is given by A/(1+A)

The collector current in a common base configuration is equal to alpha times emitter current plus leakage current

The value of collector load resistance in a transistor amplifier is less than the output impedance of the transistor

The purpose of RC or transformer coupling is to separate bias of one stage from another

The bandwidth of a single stage amplifier is more than that of multistage amplifier

Transit time is the time taken by the electrons or holes to pass from the emitter to the collector

To obtain good gain stability in a negative feedback amplifier, A is very much greater than 1

The basic concept of the electric wave filter was originated by Campbell and Wagner

Common-base configuration has the lowest current gain

Common-base and Common-collector transistor configuration offers no phase reversal at the output

The number of stages that can be directly coupled is limited because change in temperature can cause thermal instability

The input capacitor in an amplifier is called coupling capacitor

AC load line has a/an bigger slope compared to that of dc load line

A multistage amplifier uses at least two transistors

RC coupling is used for voltage amplification

An ammeter’s ideal resistance should be zero

Amplifier is the circuit that can increase the peak-to-peak voltage, current or power of a signal

When the non-linear distortion in an amplifier is D without feedback, with negative voltage feedback it will be D/(1+A)

A tuned amplifier uses LC tank load

The voltage gain over mid-frequency range in an RC coupled amplifier is constant

The input impedance of an amplifier increases when negative voltage feedback is applied

The input impedance of an amplifier decreases when negative current feedback is applied

To obtain the frequency response curve of an amplifier generator output level is kept constant

Relaxation oscillator – a type of oscillator wherein the frequency is determined by the charge and discharge of resistor-capacitor networks used in conjunction with amplifiers or similar devices

The driver transformer has center-tapped secondary to provide two signals 180 out of phase to transistors of push-pull circuit

The advantage of RC coupling scheme is economy

A type of filter which have a single continuous transmission band with neither the upper nor the lower cut-off frequencies being zero or infinite is called band pass filter

GPS – an instrument use to measure ones location in terms of coordinates

Transformer coupling is used for power amplification

The typical value of coupling capacitor in RC coupling is about 10 μF

An electronic transfer from one stage to the next is termed as coupling

An amplifier configuration where the input signal is fed to the emitter terminal and the output from the collector terminal is called common base

If the noise factor of an ideal amplifier expressed in dB, then it is 0

A feedback circuit is independent of frequency

The basic purpose of applying negative feedback to an amplifier is to reduce distortion

The capacitors are considered open in the dc equivalent circuit of a transistor amplifier

10 kHz frequency produces the highest noise factor

Power amplifier handle large signals

The operating point is generally located at the middle of dc load line in class A operation

Low voltage gain describes a common collector amplifier

The general characteristics of a common base amplifier are high voltage gain, low current gain, high power gain and very low input resistance

To amplify dc signal, multistage amplifier uses Direct coupling

Klystron oscillator is used in order to produce frequencies in the microwave region

Practically, the voltage gain of an amplifier is expressed in dB unit

Transformer coupling provides maximum voltage gain

The gain of an amplifier reduces when negative feedback is added

Feedback factor is always less than 1

Class A operation is used for general amplification where no distortion can be tolerated

Class B operation is used either where the signal needs to be cut in half, such as in pulse detector or noise detectors or where push-pull operation of two stages is required

Class AB operation is used where a portion of a signal only is required, such as the synchronizing pulse separator of a television receiver

Class C operation has little use in general purpose amplifier, but is used in high frequency oscillators

Transformer coupling provides high frequency because its DC resistance is low

Class C operation can have 100% efficiency

The efficiency of class AB operation has a maximum of between 50% to 78.5%

Transformer coupling is generally employed when load resistance is small

The smaller the voltage regulation, the better the operation of the voltage supply circuit

In transistor amplifiers, Step down transformer is used for impedance matching

If an amplifier has a power gain of 100, then its dB gain is 20

In order to have more voltage gain from a transistor amplifier the transistor used should have thin base

The final stage of an amplifier uses transformer coupling

The largest theoretical voltage gain obtained with a common collector amplifier is unity

Increasing the overall Beta is an advantage of darlington pair

The frequency of oscillation is inversely proportional to square root of L and C in an LC oscillator

An oscillator employs positive feedback

The reason why RC coupling is not used to amplify extremely low frequencies is that electrical size of coupling capacitor becomes very large

A pair of filter common on high fidelity system which separate audio frequency band signals into two separate groups, where one is fed to the tweeter and the other to the woofer is called cross over network

The frequency response of transformer coupling is poor

The simplest variable-frequency sinusoidal oscillator is the Armstrong circuit

Current gain is provided by a CB transistor amplifier

In the initial stages of a multistage amplifier, RC coupling is used

The gain of an amplifier with feedback is known as closed loop gain

Negative feedback is employed in amplifiers

The gain of an amplifier is expressed in db unit because human ear response is logarithmic

About 50 μF is the typical value of the emitter bypass capacitor in a multistage amplifier

In a multistage amplifier, if the stages have R and C component only, class A operation is apparent

Capacitance is normally varied in order to change frequency of oscillation

Power gain is the main consideration in the output stage of an amplifier

Transformer coupling provides high gain because of impedance matching can be achieved

When negative voltage feedback is applied to an amplifier, its output impedance decreases

An LC oscillator cannot be used to produce very low frequencies

A transistor converts dc power into ac power

Hartley oscillator is commonly used in Radio receivers

An oscillator oscillates due to positive feedback

Generally, tuned amplifiers are operated in class C

A tuned amplifier is used in Radio frequency

The ratio of output to input impedance of a CE amplifier is moderate

For a constant output frequency, the simplest sinusoidal oscillator circuit to construct is the crystal circuit

The frequency stability of the oscillator output is maximum in Wein bridge oscillator

Transformer coupling introduces frequency distortion

A pulsating dc applied to power amplifiers causes hum in the circuit

The disadvantage of impedance matching is that it gives distorted output

In a phase-shift oscillator, three RC sections are generally used

In phase-shift oscillator, R and C are the frequency determining element

The input impedance of CC amplifier depends strongly on load resistance

Electrolytic capacitors are used in transistor amplifiers

An important limitation of crystal oscillator is its low output

Both positive and negative type of feedback is used in Wien bridge oscillator

Transformer coupling is the most costly coupling

Piezoelectric effect in a crystal – voltage is developed because of mechanical stressThe input resistance of a common emitter amplifier is affected by Re, re and

More than 10,000 is the typical Q of a crystal

X is the axis that connects the corners of a crystal

Push-pull amplifier is usually employed at the output stage of an amplifier

The size of a power transistor is made considerably large to dissipate more heat

When crystal frequency increases with temperature, it has positive temperature co-efficient

The purpose of the bypass capacitor in a common-emitter amplifier is it increases voltage gain

An emitter follower is equivalent to common collector amplifier

The crystal oscillator frequency is very stable due to high Q of the crystal

The bandwidth of an amplifier increases when negative feedback is applied

The term 1+A in the expression for gain with negative feedback is known as sacrifice factor

Emitter follower employs 100 % negative feedback

Radio transmitter application would most likely find a crystal oscillator

Collector efficiency is the most important consideration in power amplifiers

When the gain versus frequency curve of a transistor amplifier is not flat, frequency distortion is present

In a Colpitt’s oscillator, feedback is obtained from the center of split capacitors

When the collector resistor in a common emitter amplifier is increased in value the voltage gain increases

Output signal of a CE amplifier is always out of phase with the input signal

The purpose of capacitors in a transistor amplifier is to couple or bypass ac component

When CE configuration is used for an oscillator, the voltage fed back must be inverted by 180

Class B operation has a maximum possible efficiency of 78.5 %

Crystal oscillator – the most stable sine-wave oscillator which uses piezo-electric quartz crystal

To sustain oscillations, the power gain of the amplifier may be equal to or greater than 1

In a phase-shift oscillator, 180 phase-shift is obtained by three RC sections

Feedback circuit usually employs resistive network

Emitter follower is used for impedance matching

Increased over gain is a characteristic of cascaded amplifiers

Logic analyzer is used to sample and display system signal

Quartz crystal is most commonly used in crystal oscillators because it has superior electrical properties

The operating frequency of a Wien-bridge oscillator is given by 1/(2πRC)

Class C gives the maximum distortion

Low efficiency of a power amplifier results in more battery consumption

In an LC oscillator, the frequency of oscillations is given by 1/(2πsqr(LC))

Class A operation has a maximum possible efficiency of 50%

Common emitter amplifier is a choice when higher power gain is a requirement

The signal generator generally used in laboratories is Wien-bridge oscillator

A buffer amplifier is used for minimum loading and minimum mismatch

Parasitic oscillations are caused by transistor interelectrode capacitance

Crystal oscillator is a fixed-frequency oscillator

The approximate operating frequency of a phase-shift oscillator is given by 1/(2πRC sqr(6))

The frequency of the ripple voltage at the output of a full-wave rectifier at 60 cycles is 120 cyles

Cascaded amplifiers total decibel gain is equal to the product of the individual gains

In an LC oscillator, if the value of L is increased for times, then frequency of oscillation is decreased 2 times

A class A power amplifier is otherwise known as single ended amplifier

The power input to a power amplifier is dc quantity

When shock-excited, a crystal will produce alternating emf longer than an LC circuit because crystal has fewer losses

The stability of a regulated power supply is equivalent to change of output voltage over the change in supply voltage

Oscillator circuit that uses a tapped coil in the tuned circuit is called Hartley

If you move towards an oscillating circuit, its frequency changes because of hand capacitance

The number of transistor in a single stage amplifier is one

Series current negative feedback occurs when the feedback voltage is proportional to the output current

An amplifier with efficiency 85% is likely to be Class C

180 is the phase difference between the output and input voltage of a CE amplifier

Class C operation is preferred in oscillators because it is more efficient

Sinewave oscillator – a type of oscillator which are composed of one or more amplifying devices with some frequency-determining networks introducing positive feedback at a particular frequency so that oscillation is sustained at the frequency

High input impedance of a transistor is desired

78.5% is the maximum collector efficiency of class B

when a transistor is cut off maximum voltage appears across transistor

In an LC circuit, when the capacitor energy is maximum, the inductor energy is minimum

The reciprocal of feedback factor is the approximate gain of an amplifier with negative feedback

The operating point in a transistor amplifier moves along ac load line when an ac signal is applied

An oscillator converts dc power into ac power

Transistor is the active device in a transistor oscillator

When the collector supply is 5 V, then collector cut off voltage under dc conditions is 5 V

The common base amplifier has a lower input resistance compared to CE and CC amplifier

The voltage gain decreases when a FET with a lower transconductance is substituted into a FET amplifier circuit

In the zero signal conditions, a transistor sees dc load

The current gain of an emitter follower is less than 1

The current in any branch of a transistor amplifier that is operating is the sum of ac and dc

An ideal differential amplifiers common mode rejection ratio is infinite

An open fuse circuit has a resistance equal to infinity

The purpose of dc conditions in a transistor is to set up operating point

The ac variation at the output side of power supply circuits are called ripples

The purpose of emitter capacitor is to avoid voltage drop in gain

A common emitter circuit is also called grounded emitter circuit

The output signal of a common-collector amplifier is always in phase with the input signal

Unity is the ideal maximum voltage gain of a common collector amplifier

The output power of a transistor amplifier is more than the input power due to additional power supplied by collector supply

When a transistor amplifier feeds a load of low resistance, its voltage gain will be low

The capacitance are considered short in the ac equivalent circuit of a transistor amplifier

For highest power gain, CE configuration is used

The most important characteristic of a common collector amplifier is that it has high input resistance

CC configuration is used for impedance matching because its input impedance is very high

Power stage is the other name of the output stage in an amplifier

When amplifiers are cascaded the overall gain is increased

In a common emitter amplifier, the capacitor from emitter to ground is called bypass capacitor

A class A power amplifier uses one transistor/s

25% is the maximum collector efficiency of a resistance loaded class A power amplifier

50% is the maximum collector efficiency of a transformer coupled class A power amplifier

Class C amplifier are used as RF amplifiers

If the capacitor from emitter to ground in a common emitter amplifier is removed, the voltage gain decreases

Comparatively, power amplifier has small beta

The driver stage usually employs class A power amplifier

The push-pull circuit must use class B operation

A complementary-symmetry amplifier has one PNP and one NPN transistorPower amplifiers generally use transformer coupling because transformer coupling provides impedance matchingThe output transformer used in a power amplifier is a/an step-down transformerTransformer coupling can be used in either power or voltage amplifiersWhen negative current feedback is applied to an amplifier, its output impedance increasesThe quiescent current of a FET amplifier is IdThe frequency response of the combined amplifier can be compared with an AND gateMinimum interference with frequency response can be given by direct couplingThe impedance of a load must match the impedance of the amplifier so that maximum power is transferred to the loadThe ratio of output rms power in watts to the input dc power in watts in the different amplifier class is called efficiencyThe voltage gain of a common collector configuration is unity.Transmit time is the time taken by the electrons on holes to pass form emitter to collector

ENERGY CONVERSION

Cell – a device that transforms chemical energy into electrical energy

Cell – a device that is capable of converting chemical energy into electrical energy

Edison cell – a secondary cell whose active positive plate consists of nickel hydroxide, and active negative-plate material is powdered iron oxide mixed with cadmium. Its typical output when fully charged is Vo = 1.2V

If a cell can be charged after it is depleted, it is considered as a secondary cell, a storage cell, and an accumulator

Primary cell – cell that cannot be recharged which cannot restore chemical reaction

Primary cell – a cell whose chemical reaction is not reversible

Battery – a voltage source in a single container made from one or more cells combines in series, parallel, or series-parallel

A battery is used to supply a steady dc voltage

In a dry cell, the internal resistance increases as it aged

Flash current – the maximum current a cell can deliver through a 0.01 ohm load during testing

In batteries, the material used to insulate the positive plates from negative plates are technically called separator

Leclanche cell – a primary cell with carbon and zinc as its positive and negative electrodes respectively, and an electrolyte of either a gel or paste. This is commonly known as dry cell

Silver-cadmium cell has a nominal open-circuit voltage of 1.05 V

Photovoltaic material – substance, which generates a voltage when exposed to light

Photovoltaic cell – a cell whose voltage is generated as a function of light

Silicon, Selenium, Germanium – substance used in photovoltaic cells

Thermoelectric junction – a junction between two conductors that exhibits electrical characteristic under condition of changing temperature

Thermoelectricity – Electricity that is generated due to heat, as in thermocouple

Prime mover – the source of mechanical power to turn the rotors of alternators, large and small, A.C and D.C

Generators – electrical machines that convert mechanical energy to electrical energy

Rotary converter – electrical machine that converts ac voltage to dc voltage, or vice versa

Frequency converter – electrical machine that changes ac voltage at one frequency to another ac voltage at another frequency

Elementary generator – it consist of a single coil rotated in a magnetic field and produces an A.C. voltage

Generation of voltage in a generator can only happen when there is a relative motion between conducting wires and magnetic line of force

Electro/permanent magnets and armature winding – two essential parts in rotating generators

In electrical machines, armature winding is the set of conductors wound on laminated cores of good magnetic permeability

In dc generator, commutator converts the alternating emf to DC

Generally, in dc generators, the armature winding is rotated with respect to a stationary magnetic field produced by electromagnets or permanent magnets

In electrical machines, ac voltage is generated at the armature winding

Generally in ac generators, the electromagnets or permanent magnets are rotated with respect to the stationary armature winding

Self-excited shunt generator – a dc generator whose excitation is produced by a winding connected to its own positive and negative terminals

Field poles in electric machines are always an even number of them

In a compound generator, series field winding usually has a lower resistance

In dc-compound generator shunt field winding is relatively made of fine wires

Voltage vs. load characteristic is important that you should consider in choosing a dc-generator

The purpose of laminating the field poles and armature of a dc machine is to reduce eddy current

An alternator with a lagging power factor of 0.8 will have a greater than voltage regulation at unity power factor

With alternators connected in parallel, the frequency of the system can be changed by changing the rpm of the prime movers

With alternators connected in parallel, the voltage of the system can be changed by changing the field excitation

If an ac generator is to be driven from prime mover having variable speed, such as aircraft engine, a constant speed drive (CSD) must be used.

0% is the voltage regulation when the full load voltage is the same as no-load voltage assuming a perfect voltage source

Hydraulic turbines are usually used to drive low-speed alternators

Steam turbines are usually used to drive high-speed alternators

High-speed alternators are smaller then low-speed

Carbon brushes are widely used in dc machines because it lubricates and polishes the contacts

Alternators have less chance to hunt if driven by steam turbines

In alternators, the purpose of damper windings is it prevents hunting

Parallel operation is the term that applies to the use of two or more generators to supply a common load

In paralleling ac generators, phase angle is very important

Jogging – description used for generators trying to self-adjust its parameters before paralleling with on line generators

In changing power from one generator to another, No Break Power Transfer (NBPT) is called when the operational sequence wherein the incoming generator is connected first before removing the existing generator

Break power transfer – the present on-line generator will be disconnected first before connecting the incoming generator

Alternators are rated in kVA

In electrical power distribution, main transmission lines is the first distribution line from the main generating station

The lines which carry the energy from the transformer to a customer’s service are called secondary distribution lines

In electrical power generating/distribution company, distribution of power to the customers is their highest expensesIn electrical power distributions, porcelain insulator is generally used

Motors – electrical machines that convert electrical energy to mechanical energy

Synchronous type of ac-motor, uses a dc-generator to supply dc-excitation to the rotating field

Generally in dc motors, the armature winding is supplied with current; or the armature is placed inside a set of radially supported magnetic poles

In ac motors, generally current is sent into the armature winding; or the armature winding is usually placed in a stationary laminated iron core and the rotating element may or may not be a set of magnetic poles, it depends on the type of motor

Among the dc motors, series produces the highest torque

Shunt – dc motor that has the most stable speed

In dc motor, during starting severe arcing happens

The primary reason why carbon brushes are preferred over copper brushes in dc motors is because they produce less arcing

Counter emf or back emf – in dc motors, the emf developed which opposes to the supplied voltage

To minimize arcing during starting of dc motors, a resistance should be added to limit the current in the armature winding

Series dc motors’ speed is greatly affected by a change in load. It will even run-away if the load is removed

Dc motors – motors whose speed can be easily controlled

When a dc motor has no load, the back emf becomes maximum

We get a maximum mechanical power from a dc motor Eb = 1/2V

The torque of a dc motor is directly proportional to the field strength and armature current

Friction loss – one cause why the shaft torque is less than the developed armature torque of a dc motor

Series – considered as a variable speed motor

The most common method used in varying the speed of a dc motor is by varying the field strength

The running speed of a dc series motor is greatly affected by the load

In choosing a motor for a particular application, you should consider the speed-torque characteristic

The dc series motor will overspeed when its load is removed

Differentially compounded – a motor whose speed increases as the load is increased

Flux and speed are the factors that affect iron losses in a dc motor

One advantage of a cumulatively compounded motor is that it does not run widely at light loads, this feature is due to shunt winding

In applications where an almost constant speed is required, a dc shunt motor is a good choice

In applications where a high torque is needed during starting dc series motor is preferred

In applications where sudden heavy loads happen for short duration, a cumulatively compounded motor is the best choice

In motors of the same rating, dc shunt has the least starting torque

Speed is a factor that affect friction and winding loses in dc motorsIn dc motors, power loss is contributed greatly by copper loss

Dirt on the commutator may produce excessive sparking

Motor vibrations are usually caused by worn bearings

When a motor is overloaded, it will usually overheat

Dc series motor produces the highest increase in torque considering the same increase in current

When an armature opens in dc motor, it may cause intermittent sparking

Motors take large current during starting because there’s still a low back emf

In dc motors, the speed will decrease with an increase in field strength

When armature current is increased in a dc motor, its armature reaction will also increase

To reduce sparking in dc motor, brushes are positioned such that they will be with the direction of the rotation

Polyphase motors are best suited for heavy-load application

Dc shunt motor speed can be controlled electronically by using a thyristor in series with the armature winding

SCR thyristor is commonly used in motor speed control

In controlling motor speed, the SCR control the firing angle

In motor speed control, trigger circuit is responsible for SCR firing

Rectifier – a circuit that converts ac-voltage to dc-voltage

Dc-converter – conversion from dc-voltage to another dc-voltage

Ac-converter – a converter that changes ac-voltage to another ac-voltage level

Inverter must be used if one wished to change dc voltage into ac voltage

cycloconverter – a converter that changes ac-voltage frequency from one to another.

In electronic converters, square-wave signal is mostly used to trigger the active device

A transformer consist of two coils wound on a common core

Transformer is considered by many as an efficient device due to the fact that it is a static device

With transformer, copper loss is measured when performing open-circuit test

Open-circuit test with transformers is always done on low-voltage winding

Short-circuit test with transformers is always done on low-voltage winding

When the transformer secondary winding is short-circuited, its primary inductance will increase

Natural air cooling – cooling system for transformers with ratings less than 5kVA

For transformers, zero efficiency happens when it has no-load

For transformers, maximum efficiency happens when copper loss is equal to constant loss

In constructing transformers, the primary and secondary winding should have tight magnetic coupling

Voltage per turn and ampere-turns are the two parameters in transformer that are the same in both primary and secondaryIn transformer, the amount of copper used in the primary is almost equal as that of secondary

At very low frequencies, transformers work poorly because its magnetizing current will be very high

If a power transformer is to be operated at very high frequency, it will have a very high core loss

Primary and secondary are coupled electrically and magnetically in autotransfomers

In a single-phase transformer, the core flux is alternating

The transformer might burn out when its primary is connected to at DC supply

Generally, you consider the use of core-type transformer at high voltage and low current applications

In current transformers, when its primary is energized the secondary should never be open-circuited

An ideal transformer is the one with no losses and leakage reactance

The effect of air gaps at the transformer core is it increases magnetizing current

Eddy currents are wasteful current which flow in cores of transformers and produces heat

Nothing will happen to the eddy current loss in transformers when the load is increased

Leakage flux in transformers will cause voltage drop in the windings

The increase in temperature in a transformer is mainly due to apparent power

In transformers, the voltage per turn at the primary is the same as the secondary

In transformer windings, the more number of turns the higher is the voltage

Core-type transformers has a shorter magnetic path

Practically 85% is copper loss to the total loss in transformers

The purpose of laminating the core of a transformer is to decrease eddy current loss

Large transformers have approximately an efficiency of 95%

The loss in a transformer due to the changing field is called hysteresis loss

Coefficient of coupling – the ratio of the amount of magnetic flux linking a secondary coil compared to the flux generated by the primary coil

Mutual inductance between two coils can be decreased by moving the coils apart

An advantage of full-wave rectifier over half-wave rectifier: the tube will conduct during both halves of the input cycle

The circuit that converts ac-voltage to a dc-voltage is called a rectifier

Half-wave – a rectifier that uses either the positive or negative portion only of the main supply

For a half-wave rectifier, the average output voltage is 31.8% of the maximum ac-voltage

121% - percent ripple of a half-wave rectifier

To double the capacity of the half-wave rectifier, a full-wave rectifier, dual supply must be used

0.90 Vmax – the dc-voltage of a full-wave bridge rectifierVdc = 0.90 Vrms

0.48 – ripple factor of a full-wave rectifier

To improve the dc output voltage of a power supply, a filter capacitor may be installed

Making the filter capacitor large in a power supply results to an increase of the dc-voltage

In capacitor-filtered power supply, the ripple voltage drops to zero if the load is disconnected

Multi-section LC-filter power supply filter gives the smallest ripple voltage

Regulation is a better alternative to reduce further the ripples

Shunt regulator – a voltage regulator connected in parallel with the load

Shunt regulator is the most inefficient

Zener diode – voltage reference element in most voltage regulators

In voltage regulators, the control element controls the amount of current, voltage and power

Op-amp – the element/device used as a comparator in most voltage regulators

Voltage divider network – sampling circuit used in most voltage regulators

Most voltage regulators use BJT as their control element

Switching regulators – the most efficient voltage regulator and is therefore used in high-current high-voltage applications

78XX – three-terminal fixed positive voltage regulators commonly used in industry

The regulated output voltage of a 7924 regulator is -24 V

317 – a three-terminal variable positive voltage regulator

337 three-terminal IC regulator has a variable negative voltage output

In a three-terminal adjustable positive voltage regulator (317), 1.25 V is the band-gap voltage between the output terminal and adjustment terminal

Typical ripple rejection of most three-terminal voltage regulators is 0.1%

The simplest way of protecting power supplies from reverse-polarity / reverse-current flow is by a reverse-biased diode

A crowbar circuit is used as an over-voltage protection in power supplies

Switching regulators dissipate less power and therefore generate less heat

Active device used in switching regulators may experience large over-currents during conduction (turn-on-state) and large over-voltages during turn-off. These excessive currents and voltages may cause distraction or damage of the active devices. We protect them by installing a snubber circuit

Power conditioners clean-up or shape-up the utility-supply voltage form disturbances such as, overvolt, undervolt, voltage spikes, and harmonic distortions

Uninterruptible power supply – a power supply that continuously provides protection against undervoltage, overvoltage and even power outages

Power Generator / Sources / Principles / Applications

A battery is a group of cells that generate electric energy form their internal chemical reaction

The main function of a batter is to provide a source of steady dc voltage of fixed polarity

The volt is a unit of electromotive force

A transformer will work on ac only

In a chemical cell, current is the movement of positive and negative ions

The speed of a dc motor is inversely proportional to flux per pole

Low-speed alternators are driven by hydraulic turbines

High-speed alternators are driven by steam turbines

The common 9-V flat battery for transistor radio has six cells connected in series

For the same rating, the size of low-speed alternator is more than that of high speed alternator

Silver-zinc, nickel-iron, lead-acid are examples of secondary cell

Carbon-zinc, zinc chloride, mercuric oxide are examples of primary cell

12 V is the nominal output of an automotive battery having six lead-acid cells in series

The brush voltage drop in a dc machine is about 2 V

Carbon brushes are used in a dc machine because carbon lubricates and polishes the commutator

Carbon-zinc dry cell and lead-sulfuric wet cell are considered as the main type of battery

The main function of a dc motor is to change electrical energy to mechanical energy

Shunt motor has the best speed regulation

Voltaic cell – a method of converting chemical energy into electric energy by dissolving two different conducting materials in an electrolyte

A commulatively compounded motor does not run at dangerous speed at light loads because of the presence of shunt winding

DC shunt motors are used in those applications where practically constant speed is required

Galvanic cell is the other name of voltaic cell

For the same rating series motor has the highest starting torque

The voltage regulation of an alternator with a power factor of 0.8 lagging is greater than at unity power factor

Commulatively compounded motor is the most suitable for punch presses

In a vacuum cleaner, series motor is generally used.

Sealed rechargeable cell – a type of secondary cell that can be recharged but with an electrolyte that cannot be refilled

Silver-cadmium is a secondary cell with a nominal open-circuit voltage of 1.1 V

Series is a variable speed motor

The most commonly used method of speed control of a dc motor is by varying field strength

Electrochemical series and electromotive series give the relative activity in forming ion charges for some of the chemical elements

The ac armature winding of an alternator is always star-connected

The air-gap in an alternator is much longer than in an induction machine

Nickel-iron cell is a secondary cell with a nominal open-circuit voltage output of 1.2 and is otherwise known as Edison cell

A dc series motor is most suitable for cranes

Commulatively compounded motors are suitable for elevators

The voltage output of a cell depends on its elements

The alternators driven by steam turbines do not have a tendency to hunt

Damper windings are used in alternators to prevent hunting

Leclanche’ cell is the other name of carbon-zinc cell

The primary leakage flux link primary winding only

Overheating of a dc motor is often due to overloads

A small 9-V battery might be used to provide power to and electronic calculator

The frequency of the system with which several alternators are parallel can be increased by simultaneously increasing the speed of prime movers of all generators

A transformer is an efficient device because it is a static device

The amount of back emf of a shunt motor will increase when the field is strengthened

Three cells connected in series form a battery

Turns ratio can be found in a transformer with open-circuit test

Transformers having ratings less then 5kVA are generally natural air cooled

An example of a rechargeable dc source is a lead-acid battery

The voltage of the bus-bar to which several alternators are paralleled may be raised by simultaneously increasing field excitation of all alternators

The rating of an alternator is expressed in kVA

Commulatively compounded motors are used in applications where sudden heavy loads for short duration is required

Series motor never uses belt-connected load

A stand-alone solar power system uses solar panels and batteries

A transformer will have zero efficiency at no-load

The efficiency of a transformer will be maximum when copper loss is equal to constant loss

The armature winding of a dc machine is a closed-circuit winding

The speed at which a 6-pole alternator should be driven to generate 50 cycles per second is 1000 rpm

Connecting batteries of equal voltage in parallel multiplies the current available

Lead-acid battery – a storage battery in which the electrodes are grids of lead containing lead oxide that change in composition during charging and discharging and the electrolyte is dilute sulfuric acid

Leclanche cell – the common dry cell, which is a primary cell having a carbon positive electrode and a zinc negative electrode in an electrolyte of sal ammoniac and a depolarizer

The maximum flux produced in the core of transformer is inversely proportional to supply frequency

A transformer is so designed that primary and secondary windings have tight magnetic coupling

For carbon-zinc cells in series will provide about 6 Vdc

Float charging refers to a method in which the charger and the battery are always connected to each other for supplying current to the load

Universal motor – a series motor designed to operate on dc or ac

Ward-Leonard system – combination of ac motor, dc generator, and exciter to provide adjustable voltage dc power to a dc motor

A motor takes a large current at starting because back emf is low

A series motor will overspeed when load is removed

When the load on an armature is increased, the terminal voltage increases if the load power factor is leading

The efficiency of the turbo-alternator increases with increase in speed.

2.1 V is the output of a lead-acid cell

In an alternator, the effect of armature reaction is minimum at power factor of unity

For given number of poles (>2) and armature conductors, a lap winding will carry more current than a wave winding

An 8-pole duplex lap winding will have 16 parallel paths

To increase voltage output, cells are connected in series

To increase current capacity, cells are connected in parallel

Two things which are same for primary and secondary of a transformer are ampere-turns and voltage per turn

A transformer operates poorly at very low frequencies because magnetizing current is abnormally high

In an auto transformer, the primary and secondary are magnetically as well as electrically coupled

Faure storage battery – a storage battery in which the plates consist of lead-antimony supporting grids covered with a lead oxide paste, immersed in weak sulfuric acid

Nickel-cadmium cell is a dry storage cell

The field structure of a dc machine uses salient-pole arrangement

Small dc machines generally have 2 poles

The armature of a dc machine is laminated in order to reduce eddy current loss

To produce an output of 7.5V, 5 carbon-zinc cells are connected in series

The demand for a large increase in torque of a dc series motor is met by a large decrease in speed

As the load increases, a differentially compounded motor will speed up

The flux in the core of a single-phase transformer is purely alternating one

The primary of a transformer may burn out when connected to a dc supply

A constant-voltage source has low internal resistance

If the excitation of an alternator operating in parallel with other alternators is increased above the normal value of excitation, its power factor becomes more laggingThe synchronous reactance of an alternator is generally 10 to 100 times greater than armature resistance

DC series motors are used in those applications where high starting torque is required

A dc motor is still used in industrial applications because it provides fine speed control

The stator of an alternator is wound for the same number of poles as on the rotor

Carbon brushes are preferred compared to copper brushes they reduce sparking

The synchronous reactance of an alternator decreases as the iron is saturated

A 4-pole dc machine has 4 magnetic circuits

The current in armature conductors of a dc machine is ac

The ac armature winding of an alternator operates at much higher voltage than the field winding

The field poles and armature of a dc machine are laminated to reduce eddy current

The back emf or counter emf in dc motor opposes the applied voltage

The synchronous reactance of an alternator is due to armature reactionBack emf in a dc motor is maximum at no load

The mechanical power developed in a dc motor is maximum when back emf is equal to one-half the applied voltage

The core-type transformer is generally suitable for high voltage and small output

The transformer that should never have the secondary open-circuited when primary is energized is current transformer

The field winding of an alternator is dc excited

The salient-pole construction for field structure of an alternator is generally used for 8-pole machine

When the speed of a dc motor increases, its armature current decreases

The frequency of emf generated in an 8-pole alternator running at 900 rpm is 60 Hz

In case of a 4-pole machine, 1 mechanical degree corresponds to 2 electrical degrees

The torque developed by a dc motor is directly proportional to flux per pole times armature current

Induction motor – ac machine in which the torque is produced by the interaction of currents in the stator and currents induced in the motor by transformer action

Synchronous motor – machine in which torque is produced by the interaction of ac currents in the stator and dc currents in the rotor turning in synchronism

The main drawback of a dc shunt generator is that terminal voltage drops considerably with load

DC machines which are subjected to abrupt changes of load are provided with compensating windings

The shaft torque in a dc motor is less than total armature torque because of iron and friction losses in the motor

Armature reaction in a dc motor is increased when the armature current increases

An ideal transformer is one which has no losses and leakage reactanceIf a power transformer is operated at very high frequencies, then core losses will be excessive

With respect to the direction of rotation, interpoles on a dc motor must have the same polarity as the main poles behind them

The open-circuit test on a transformer is always made on low-voltage winding

In the short circuit test in a transformer, low-voltage winding is generally short-circuited

In a dc motor, the brushes are shifted from the mechanical neutral plane in a direction opposite to the rotation to reduce sparking

The number of cycles generated in a 6-pole alternator in one revolution is 3

If the lagging load power factor of an alternator is decreased, the demagnetizing effect of a armature reaction is increased

In very large dc motors with severe heavy duty, armature reaction effects are corrected by using compensatory windings in addition to interpoles

The amount of copper in the primary is about the same as that of secondary

The open-circuit test on a transformer gives iron losses

The speed of a shunt motor is practically constant

The running speed of a dc series motor is basically determined by load

If the excitation of an alternator operating in parallel with other alternators is decreased, its power factor becomes more leading

The distribution of load between two alternators operating in parallel can be changed by changing driving torques of prime movers

After a shunt motor is up to speed, the speed may be increased considerably by decreasing field circuit resistance

When the secondary of a transformer is short-circuited, the primary inductance is decreased

For the same rating, shunt motor has the least starting torque

The deciding factor in the selection of a dc motor for a particular application is its speed-torque characteristic

The rotor of a turbo-alternator is made cylindrical in order to reduce windage losses

The disadvantage of a short-pitched coil is that voltage round the coil is reduced

The demand for a large increase in torque of a dc shunt motor is met by a large increase in current

For 20% increase in current, the motor that will give the greatest increase in torque is series motor

Lead sulfide cell – a cell used to detect infrared radiation; either its generated voltage or its change of resistance may be used as a measure of the intensity of the radiation

Local cell – a galvanic cell resulting from difference in potential between adjacent areas on the surface of a metal immersed in an electrolyte

Series motor is used to start heavy loads

When load is removed, the motor that will run at the highest speed is the series motor

The friction and windage losses in a dc motor depends upon speed

If a transformer core has air gaps, then magnetizing current is greatly increased

The effect of leakage flux in a transformer is to cause voltage drop in the windings

The iron losses in a dc motor depend upon both flux and speed

The greatest percentage of power loss in dc motor is due to copper loss

Excessive sparking at the brushes may be caused due to dirt on the commutator

The temperature rise of a transformer is directly proportional to apparent power

Magnetization curve – a graphical relation between the generated emf and field current of a machine

Majority of alternators in use have revolving field type construction

The stator of an alternator is identical to that of a 3-phase induction motor

Excessive motor vibration is caused by worn bearings

Hot bearings of a dc motor may be caused by lack of or dirty lubricant

Intermittent sparking at the brushes of dc motor may be caused due to an open armature coil

When load on a transformer is increased, the eddy current loss remains the same

The yoke of a dc machine is made of cast steel

The armature of a dc machine is made of silicon steel

The voltage per turn of the primary of a transformer is the same as the voltage per turn of the secondary

The winding of the transformer with greater number of turns will be high-voltage winding

The coupling field between electrical and mechanical systems of a dc machine is magnetic field

The real working part of a dc machine is the armature winding

4-pole dc machines are most common

The core-type transformer provides shorter magnetic path

Compound machine – a machine with field excitation by both shunt and series windings

The armature winding of a dc machine is placed on the rotor to facilitate commutation

The yoke of a dc machine carries one-half of pole flux

The greatest eddy current loss occurs in the armature of a dc machine

The commentator pitch for a simplex lap winding is equal to 1

In a simplex wave winding, the number of parallel path is equal to 2

In a practical transformer, copper losses account to 85% of the total losses

By laminating the core of a transformer, eddy current loss decreases

The number of parallel paths in a simplex lap winding is equal to number of poles

In a dc machine, the number of commutator segments is equal to number of coils

A dc compound generator having full-load terminal voltage equal to the no-load voltage is called flat-compounded generator

The terminal voltage of a series generator varies widely with changes in load currentThe nature of armature winding of a dc machine is decided by commutator pitch

The voltage regulation of an alternator is larger than that of a dc generator because of complex effects of armature reaction

High-voltage dc machine use wave winding

In a lap winding, the number of the brushes required is equal to number of poles

The approximate efficiency of a large transformer is 95%

In a wave winding, the commutator pitch is approximately equal to twice the pole pitch

A triplex wave winding will have 6 parallel paths

For a given dc generator, the generated voltage depends upon both speed and flux

For the same rating, a dc machine has more weight than an ac machine

Slip – difference between the speeds of rotating magnetic field and the associated rotor

The field winding of a dc shunt motor usually carries 2% to 5% of ht rated current of the machine

A separately excited dc generator is not used because a separate dc source is required for field circuit

The effect of armature reaction is to decrease the total flux

In a dc generator, armature reaction weakens the flux at the leading pole tip

The greatest percentage of heat loss in a dc machine is due to copper loss

The size of a dc generator can be reduced by using magnetic material of high permeability

ELECTRONICS INSTRUMENTATIONS

Accuracy – the degree of exactness of measurement when compared to the expected value of the variable being measured

Measurement – the art, or process of determining the existence of knowing the magnitude of something, directly or indirectly in terms of a recognized standard

Test – a procedure, or sequence of operations for determining whether a component or equipment is functioning or working normally

In measurement, accuracy is the degree of exactness compared to the expected value of the variable being measured

A measure of consistency or repeatability of measurements is called precision

Precision is also known as reproducibility

In measurements, the sum of a set of numbers divided by the total number of pieces of data in the given set is called arithmetic mean

Error – the deviation of a reading form the expected value

Instrument errors – errors due to frictions of the meter movement, incorrect spring tension, improper calibration or faulty instruments

When an instrument is subjected to harsh environments such as high temperature, strong magnetic, electrostatic, or electromagnetic field, it may have a detrimental effects and cause errors known as environmental errors

Observation errors – errors introduced by the observer or user

Parallax error – errors in analog meter reading due to your physical position with respect to the meter scale

Deviation – the difference between any number within the set of numbers and the arithmetic mean of that set of numbers

Standard instrument/device – an instrument or device having recognized permanent or stable value that is used as a reference

Resolution – the smallest change in a measured variable to which an instrument will respond

Instrument – a device or mechanism used to determine the value of a quantity under observation

Amepe is the basic unit for measuring current flow

An instrument used to detect and measure the presence of electrical current is generally called galvanometer

D’ Arsonoval is the common type of meter moving

D’ Arsonoval meter movement – a permanent-magnet moving-coil instrument

Moving-iron instrument – an instrument which depends on current in one or more fixed-coils acting on one of more pieces of soft iron, at least one of which is movable

Moving-magnet instrument – depends on the action of a movable permanent magnet, in aligning itself in the resultant field, produced either by a fixed permanent magnet and an adjacent coil or coils carrying current, or by two or more current-carrying coils whose axes are displaced by a fixed angle

Thermocouple ammeter is mostly used in measuring high-frequency currents

Measurement of high dc-voltages is usually done by using electrostatic

Electrostatic – measuring instrument that can be used only to measure voltages

Pyrometer – this instrument measures temperatures by electric means, especially temperatures beyond the range of mercury thermometers

Pyranometer – this instrument refers to that one, which measures the intensity of the radiation, received from any portion of the sky

Infinity is the normal indication on a megger (megaohmmeter) when checking insulation

Megaohmmeter, megger – Resistance measuring instrument particularly used in determining the insulation resistance

Wattmeter – an electrodynamic meter used to measure power

Dynamometer – a device used to mechanically measure the output power of a motor

Electrodynamometer – an indicating instrument whose movable coils rotate between two stationary coils, usually used as wattmeter

Dynamometers are mostly used as wattmeter

Air friction damping method is generally used in dynamometers

Wattmeter dynamometer instrument has a uniform scale

For a dynamometer to be able to measure high current, a current transformer should be used

Error in voltmeter reading is due to loading

Error in ammeter reading is due to insertion

An ohmmeter type of meter requires its own power source

Error in ohmmeter reading is due to battery aging

Decreasing the value of the shunt resistor of an ammeter, its current measuring capability increases

Increasing the value of the series resistor of a voltmeter, its voltage measuring capability increases

Clamp probe – a device that is used to measure current without opening the circuit

Clamp-meter ammeter has no insertion error

To prevent damage of the multirange ammeter during selection, an Ayrton shunt should be used

For the greatest accuracy, the input impedance of a VOM should be as large as possible

Voltage measurement in a high impedance circuit requires a voltmeter with high input impedance

In order to make an accurate measurement as possible, the internal resistance of a voltmeter must be as high as possible

The purpose of the rheostat in ohmmeter is to compensate the aging battery of the meter

The zero-adjust control in an analog type ohmmeter is used to compensate for the differing internal battery voltage

The scale of a hot wire instrument is a squared function

Moving iron instruments have a scale function that is squared

To increase the measuring capability of a moving-iron ac ammeter, a different number of turns of operating coil should be used

PMMC electrical instrument is the most sensitive

Basically, a PMMC instrument can be used only in dc measurement

Spring action – controlling torque in PMMC

Eddy current damping method is used in induction type ammeter

Induction type instruments are mostly used as watt-hour meter

In indicating instruments, the controlling torque increases if the deflection becomes greater

Controlling torque and deflecting torque are forces that are acting on the pointer of an indicating instrument as it rest on its final deflected position

Controlling, damping, and deflecting torques are the forces acting on the pointer of an indicating instrument when it is in motion

Aluminum – material that is mostly used as a pointer in indicating instrument

A Kelvin electrostatic voltmeter uses fluid friction method of damping

Shunts in meters should have a very small temperature coefficient of resistance

In a moving coil ammeter, a swamping resistor is connected in series with the coil to compensate for temperature variations

We use the dynamometer in dc and ac

Electrostatic instrument – meter that depends for its operation on the forces of attraction and repulsion between electrically charged bodies

Induction instrument – instrument that depends for its operation on the reaction between magnetic flux set up by currents in fixed windings and other currents set up by electromagnetic induction in movable conduction parts

Permanent-magnet moving-coil instrument – a meter that for its operation, it depends on a movable iron vane which aligns itself in the resultant field of a permanent magnet and an adjacent current carrying coil

Vane-type instrument uses the force of repulsion between fixed and movable magnetized iron vanes, or the force between a coil and a pivoted vane-shaped piece of soft iron to move the indicating pointer

Kelvin voltmeter – its an electrostatic voltmeter in which an assembly of figure 8 shaped metal plates rotates between the plates of a stationary assembly when a voltage is applied between the assemblies. The length of the arc of rotation is proportional to the electrostatic attraction and thus, to the applied voltage

Magnetometer is an instrument used for measuring the strength and direction of magnetic field

Varmeter and reactive volt-ampere meter are the instrument used for measuring reactive power in vars

Bridge is a circuit that has four or more arms, by means of which one or more of the electrical constants of an unknown component may be measured

Resistance bridge, wheatstone bridge – a four-arm bridge. All arms of which are predominantly resistive; used for measuring resistance

Varley loop – this is a method of using a Wheatstone bridge to determine the distance from the test point to a fault in a telephone or telegraph line or cable

Maxwell bridge – this refers to a four-arm ac bridge used for measuring inductance against a standard capacitance

Hay bridge – refers to an ac bridge for measuring the inductance and Q of an inductor in terms of resistance, frequency and a standard capacitance

Kelvin double bridge – this is a special bridge for measuring very low resistance (0.1 or less). The arrangement of the bridge reduces the effects of contact resistance, which causes significant error when such low resistance are connected to conventional resistance bridges

Schering bridge – a type of four-arm capacitance bridge in which the unknown capacitance is compared with a standard capacitance. This bridge is frequently employed in testing electrolytic capacitors, to which a dc polarizing voltage is applied during the measurement

Wein bridge – a frequency-sensitive bridge in which two adjacent arms are resistances and the other two arm are RC combinations

When the capacitors of a Wien bridge are replaced by inductors, the bridge becomes Wein inductance bridge

Slide-wire bridge – a simplified version of the Wheatstone bridge wherein, two of the ratio arms are replaced by a 100 cm long Manganin of uniform cross-sections and provided with a slider

Radio-frequency bridge – bridge used to measure both inductive and capacitive impedances at higher frequencies

Balance bridge – a bridge wherein all legs are electrically identical

Spectrum analyzer is an electronic instrument capable of showing on screen and maybe on print, relative spacing of transmitter carriers, their sidebands and harmonics

Spectrum analyzer – an instrument capable of displaying simultaneously the amplitude of signals having different frequencies

A spectrum analyzer is a real-time analyzer

Indications of spectrum analyzer is presented by means of a CRT

Oscilloscope – an electronic measuring device that provide instantaneous visual indication of voltage excursions

Oscilloscope – an instrument that is capable of displaying waveforms by means of a fluorescence in a CRT

Storage oscilloscope – types of oscilloscopes that are able to retain the display for a longer period for analysis. The display is retained by the use of flood gun

Sampling oscilloscope uses sampling technique in processing signals having frequencies beyond its normal capabilities

Generally, oscilloscope uses electrostatic deflection

Signal generators – a device or instrument, which delivers signals of precise frequency and amplitude, usually over a wide range

The two most common audio oscillators are Wein bridge and phase-shift

The two most popular RF oscillators are Colpitts and Hartley

Noise generator – a device or instrument able to generate noise with accurate voltage for test purposes

You need a noise generator when evaluating noise characteristics of an amplifier

In RF or microwave system, reflectometer is used to measure the incidental and reflected signals

Reflectometer – a type of photometer used to measure reflection

Dip meter – a tunable RF instrument, which, by means of a sharp dip of an indicating meter, indicates resonance with an external circuit under test

Grid-dip meter – a type of dip meter employing a vacuum tube oscillator, whose indicating dc microammeter is in the grid circuit

In meter movement, you prevent the meter from oscillation and overswing by damping

When the meter is insufficiently damped, it is considered as underdamped

A meter when overdamped will become insensitive to small signals

Test and Measurement

An ammeter is an indicating instrument

As the deflection of the moving system increases, the controlling torque in an indicating instrument increases

D’Arsonval is the best type of meter movement

Wattmeter dynamometer type has uniform scale

When both deflecting and controlling torque act, the pointer of an indicating instrument comes to rest

The output voltage of a thermocouple increases with temperature

Analog instrument – an instrument in which the magnitude of the measured quantity is indicated by means of a pointer

If the pointer of an indicating instrument is in motion, damping and controlling torques oppose the deflecting torque

Electrical currents can be induced with a coil and a magnet by moving either the magnet or the coil

The fuse should never be replaced with a higher rated unit

The pointer of an indicating instrument is generally made of aluminum

The time interval that a waveform is high (or low) is the pulse width of the signal

A Wheatstone bridge is balanced if the ratio of resistors on one side of the bridge equals the ratio of resistors on the other side

The pointer of an indicating instrument is in the final deflected position, the damping torque is zero

Deflecting force – a moving system force in analog instruments which causes the moving system to deflect from its zero position

Controlling force – a moving system force in analog instruments which ensures that the deflection of the pointer for a given value of measured quantity always has the same value

All voltmeters except electrostatic is operated by the passage of current

Disc is made of conductor and non-magnetic material in eddy current damping

The time interval between pulses is called pulse delay

An oscilloscope provides easy measurement of peak to peak values

Fuse is an element in electronics which serves as a protection against overlead

Diode sensor provides a dc voltage approximately 1V to 10 mW

Hot-wire instrument has a squared scale

For time measurements, horizontal scale of the scope is used

Fluid friction damping is employed in Kelvin electrostatic voltmeter

Current range extension in moving coil instruments can be achieved by placing a low resistance resistor in shunt with the instrument

Permanent-magnet moving coil instrument can be used in dc work only

Control grid CRT element provides for control of the number of electrons passing farther into the tube

Orthogonal nulling refers to garaging the two adjustments of an AC bridge together in such a way that changing one adjustment changes the other in a special way, but changing the second adjustment does not change the first

When the vertical input is 0V, the electron beam may be positioned at the vertical center of the screenThe reason why the scale of a permanent-magnet moving coli instrument is uniform is because it is spring controlled

Thermal converters – a sensing element that provides a dc voltage less than 10mV with typical power range of 0.1 to 100 mW

Tank circuit frequency can be measured by Grid-dip meter

Shunts are generally made of Manganin material

1 μA meter is the most sensitive

A dynamometer instrument is mainly used as a wattmeter

Dynamometer movement is the most expensive

Attraction and repulsion instrument are considered as moving-iron instruments

In wheatstone bridge, bridge balance is a condition where there is no current that flows through the load

The temperature coefficient of resistance of the shunt material is negligible

In VTVMS, zero adjust is used to balance both halves of the difference amplifier or cathode-coupled amplifier

In an oscilloscope, intensity control adjusts the brightness of the spot by changing the voltage on the control grid

Damping force – a force in analog instrument which quickly brings the moving system to rest in its final position

A small swamping resistance is connected in series with operating coil of a moving coil ammeter in order to compensate for the effects of temperature variation

The typical power range of diode sensor is 0.1 nW to 10 mW

A milliameter operates on the magnetic attraction-repulsion principles

Wheatstone bridge – a dc bridge widely used for the accurate measurement of resistance

Potentiometer bridge is a dc bridge that is very useful for making extremely accurate voltage measurements

Majority of the analog measuring instrument utilizes magnetic effect

Multimeter typically provides measurement of rms values (for a sinusoidal waveform)

Dynamometer type instrument can be used for both dc and ac works

Permanent-magnet moving coil is an instrument in which springs provide the controlling torque as well as serve to lead current into and out of the operating coil

In VTVMS, sensitivity refers to the smallest signal that can be reliably measured

The frequency of rotation in some rotating machinery can be measured by a Spectral meter

An instrument used for observing voltage and current waveforms is the oscilloscope

An electrostatic force does not act on the moving systems of analog instrument

When current through the operating coil of a moving-iron instrument is tripled the operating force becomes nine times

50 mA is the typical full-scale deflection current of a moving coil instrument

Ammeter – an instrument used for measuring the amount of current flowing in a circuit

DMM – a type of meter that gives a precise reading of voltage, current or resistance where there is the generation of samples at the input and then feeds it to a digital read-out

50 mV is the typical full-scale voltage across a moving coil voltmeter

The period of a repetitive signal is one cycle of the waveform

Cathode – an element of a CRT that releases electrons when heated indirectly by a filament

Moving-iron instrument has a squared scale

A pattern displayed by oscilloscope which has a steady characteristic is called Lissajous

Changing the number of turns of operating coil extends the range of a moving-iron ac ammter

Sawtooth generator is not a basic part of a CRT

For amplitude measurements, vertical scale is calibrated in either volts per centimeter (V/cm), or millivolts per centimeter (mV/cm)

Thermocouple ammter is used to measure high-frequency currents

Electrostatic is used for measuring high direct voltage

A common technique for measuring power at high frequency is to employ a sensing element that converts the RF power to a measurable dc or low-frequency signal

The CRT provides the visual displaying showing the form of the signal applied as a waveform on the front screen of a cathode ray oscilloscope.

Electrostatic instruments are exclusively used as voltmeters

0.1 μW to100 μW is the typical power range of thermocouple sensors

An electric pyrometer is an instrument used to measure high temperature

Permanent-magnet moving coil is the most sensitive

Induction watt-hour meter is the most commonly used induction type instrument

An integrating type of instrument is the watt-hour meter

Indicating instrument is assumed to be most accurate at half of full part of the scale

On a simple ohmmeter, the 0 ohm mark is located at far right of the scale

One of the basic functions of electronic circuit is the generation and manipulation of electronic waveshapes

Cathode ray oscilloscope (CRO) provides a visual presentation of any waveform applied to the input terminals

The interval of a pulse from start to end is the period of the pulse

Cathode ray tube (CRT) is considered as the “heart” of the cathode ray oscilloscope

Phosphor – a material that glows when struck by the energetic electrons in a CRT

Thermiston sensor provides a change of resistance with typical power range of 1 μW to 10 mW and with maximum frequency greater than 100 GHz

Most AC voltmeters have an rms scale which is valid only if the input signal being measured is a sinusoidal signal

Wheatstone bridge measures dc resistance

Hay bridge is used to measure high-Q inductors (Q>10)

Maxwell bridge measures an unknown inductance in terms of known capacitance

Maxwell bridge is used for measuring medium Q coils (1<Q<10)

Wien bridge has a series RC combination in one arm and a parallel RC combination in the adjoining arm and used as a notch filter in harmonic distortion analyzer

Sensitivity of a voltmeter is express in ohm/volt

The smallest change in applied stimulus that will indicate a detectable change in deflection in an indicating instrument is called resolution

Insulation material is measured by Megger

INDUSTRIAL ELECTRONICS

Breaker – one type of circuit control device which may be manual, automatic or multi-contact

Switching a tapped inductor and using a saturable reactor are the common methods of controlling electrical power with reactance

Saturable reactor – a reactive device used in controlling electrical power by using two windings on a common iron core. The control winding is supplied with small dc-current which causes the reactance of a large ac-winding to change accordingly

Magnetic amplifier – a saturable reactor with regenerative feedback

Thyratrons in industrial electronics refers to gas-filled triode

Ignitrons – an electronic switch that has the highest single-device current capacity and can withstand overloads better

SCR – a semiconductor, electronic switch that has the highest single-device current rating

The purpose of installing thyrectors across the incoming power lines to the speed control system is to protect drive circuits from high voltage transient surges

Semiconductor devices equivalent to thyratrons are generally called thyristor

Phase control power control switching method greatly generates RFI or EMI and is therefore limited to low-frequency applications

One of the electronic semiconductor devices known as diac, function as two terminal bi-directional switch

Bidirectional-trigger diac trigger diode has the highest holding voltage

Break-over devices – general term of electronic devices used to control or trigger large-power switching devices

Trigger diode – a break-over device that is basically a diode

SCR – a four-element solid state device that combines the characteristics of both diodes and transistors

SCR - the most popular thyristor used in electrical power controllers

Conducting and non-conducting are the two stable operating conditions of an SCR

To stop conduction during which SCR is also conducting, interrupt anode current

To turn “ON” or trigger an SCR is by making the gate positive with respect to its cathode

The anode to cathode continues to conduct even if the gate triggering voltage is removed

Holding voltage – the voltage across the anode and cathode terminals of an SCR when conducting

Holding current – the minimum amount of current needed for an SCR to conduct continuously

Breakback voltage – the voltage decreased across the anode and cathode of an SCR from non-conducting state to conducting state

Minimum-gate trigger voltage is the needed voltage at the gate of an SCR before it conducts

Water cooling is the only recommended to be used for the largest power dissipating device

To increase the forward-voltage blocking capability of SCRs we connect them in series

In connecting two SCRs in series, during “OFF” state, the voltage source must be properly shared between them, but due to devices’ difference, there might be

unequal voltages across each SCR, we equalize these voltages by using a blocking-equalizing resistor

Snubber circuit – a circuit used for voltage equalization during ON-OFF switching action of SCRs in series

In controlling electrical power using phase control method with SCR/triac being the active device, firing delay angle is the period of the cycle before the device switches to conduction

SBS – a three terminal device that behaves roughly like SCR, except that it can conduct current in either direction when at ON.

Gate, anode 1 and anode 2 are the three terminals of a TRIAC

SUS – a thyristor that is very similar to an SCR except that it has low voltage and current ratings. It is very temperature stable, and is therefore suitable to be used as a triggering device

Silicon unilateral switches (SUSs) generally have a breakover voltage of 8 V, however, this value can be altered by normally connecting a zener diode. The diode is installed by diode’s cathode to SUS’s gate and diode’s anode to SUS’s cathode

Shockley diode – thyristor whose characteristic curve closely resembles that of SCR’s and SUS’s, except that its forward breakover voltage (+VBO) is not alterable, for the device has no gate terminal

The forward breakdown or breakover voltage of SCRs and triacs will decrease if the gate current is increased

For a unijunction transistor (UJT) to switch ON, the voltage between the emitter and base 1 should be greater than the peak voltage with emitter being more positive

In selecting thyristors for a particular application, thyristors with high breakdback-voltage is generally desirable

Portion in the welding process interval during which the welding current is flowing is called heat sub-interval

In automatic welding system, basically there are 5 intervals

In automatic welding, squeeze interval is the first interval wherein the material to be welded are held together

After the squeeze interval, weld interval comes next in the automatic welding system

During welding or weld interval, when a welding current is flowing the system is said to be at heat subinterval

Cool subinterval – the portion of the weld interval during which the current is absent

After the welding interval, it goes to hold interval wherein the electrode pressure is maintained on the metal surfaces

Next to hold interval is release interval in automatic welding system

After the release interval in automatic welding, the system will go to standby interval

Open-loop system – refers to the system that has no feedback and is not self correcting

The system is overdamped if a position servo system does not respond to small changes in the input

The purpose of using a differential synchro instead of a regular synchro is that differential synchros can handle more signals and also performs addition and subtraction function

Open-loop – industrial circuit or system that is not self-correcting

Closed-loop is a circuit or system that is self-correcting

Open-loop in control system means: it has no feedback, it is not self-correcting, it is not self-regulating

In control system, closed-loop means: it has feedback, it is self-correcting, it is self-regulating

When a closed-loop system is used to maintain physical position it is referred as servo system

In closed-loop control system, error is the difference in the measured value and the set value or desired value

Error signal in closed-loop systems is also known as difference signal, deviation, system deviation

In a closed-loop control system, when the error signal is zero the system is at null

Offset – the small error signal or system deviation where the system cannot correct anymore

A good closed-loop control system has the following characteristics: with very small offset signal or voltage, quick response, highly stable

In control system, the manner in which the controller reaats to an error is termed as mode of control

On-off – mode of control wherein the controller has only tow operating states. This mode is also known as ban-bang control

Proportional is a mode of control wherein the controller has a continuous range of possible position, not just two as in bang-bang control

Proportional plus integral – proportional mode of control wherein the controller is not only considering the magnitude of the error signal but as well as the time that it has persisted

Proportional plus derivative – proportional mode of control wherein the controller is not only considering the magnitude of the error signal but as well as its rate of change

Error signal magnitude, error signal period of occurrence, and error signal rate of change are being considered in Proportional plus Integral plus Derivative mode of control

If on-off mode of control is the simplest, proportional plus integral plus derivative is its opposite or the most complex

The articulated arm and cylindrical are two of the most common mechanical configuration of industrial robots

One advantage of hydraulic actuator in industrial robots include great force capability handling heavy loads

Hydraulic and Pneumatic includes two of the actuator type used in industrial robots

Servo – a system in which the precise movement of a large load is controlled by a relatively weak signal

Industrial robot – a programmable, multifunction manipulator designed to move materials, parts, tools or specific devices

Robotics – the technology for automations

The number of axis a robot is free to move is called degrees of freedom

Hydraulic fluid actuators has the greatest force capability

Hydraulic actuator requires the highest initial cost

Hydraulic robot actuator has the highest operating cost

Hydtraulic - the most messy robot actuator

Hard interrupt – a robot software or program that produces only two-position motion for a given robot axis

Point-to-point program – a robot program that has the ability to move a robot to any position within the range but without specific path

Continuous path program – a robot program that has the ability to move a robot to any position within the range with specific path

When a robot moves on several axis at the same time, it is to have compound motion

In robotics, SCARA means Selective Compliant Articulated Robot Arm or Selective Compliant Assembly Robot Arm

SCARA Robots has 4 axis of motion

SCARA Robots are designed for assembling

SCARA Robots are attractive in industry because it is relatively cheaper

Industrial Electronics / Principles / Applications

Radiation sensing – is nucleonic sensing method employing usually one or more radioisotope sources and radiation detectors

EEG – concerned with the measurement of electric signals on the scalp which arise from the underlying neutral activity in the brain (including synaptic sources)

In therapeutic radiology and in nuclear medicine, the energies of interest range from about 100 to 10000 keV

SCS is a four-layer diode with an anode gate and a cathode gate

Diac is basically a two-terminal parallel-inverse combination of semiconductor layers that permits triggering in either direction

The typical value of the interbase resistance of a UJT is between 4 to 10 kohm

PUT stands for Programmable Unijunction Transistor

Diac thyristor conducts current in both direction when turned on

SCR is a three terminal device used to control large current to a load

Seebeck effect – another term for thermoelectric effect

Forward blocking region and Reverse blocking region are the regions corresponding to open-circuit condition for the controlled rectifier which block the flow of charge from anode to cathode

The V-I characteristics for a triac in the first and third quadrants are essentially identical to those of SCR in the first quotation

When the temperature increases, the inter-base resistance of a UJT increases

The three terminals of a triac are two main terminals and a gate terminal

A triac is equivalent to two SCRs in inverse-parallel

In diagnostic radiology and for superficial therapy purpose, the energy spectrum of radiation varies from about 10 to 100 keV

The x-ray region of the electromagnetic spectrum has a corresponding range of wavelengths from 0.1 to 0.0001 nm

The three terminals of an SCR are the cathode, anode, gate

An SCR have four semiconductor layers

A triac is a bidirectional switch

The normal way to turn on an SCR is by appropriate anode current

A triac can pass a portion of both positive and negative half-cycle through the load

A diac has two terminals

An SCR combines the features of a rectifier and transistor

Gate is the control element in an SCR

A triac have four semiconductor layer

A diac has three semiconductor layer

The p-type emitter of a UJT is heavily doped

A diac has two pn junction

A UJT is sometimes called double-based diode

A diac is an AC switch

An SCR is made of silicon and not germanium because silicon has low leakage current

Gate is the control element in an SCR

Rate effect – an effect that reduces the possibility of accidental triggering of the SCS

Sawtooth generator is a common application of UJT

Diac does not have a gate terminal

An SCR is a current triggered device

When a UJT is turned on the resistance between emitter terminal and lower base terminal decreases

A UJT has one pn junction

The UJT may be used as a sawtooth generator

The normal way to turn on a diac is by breakover voltage

Essentially power electronics deals with the control of ac power at 60 Hz frequency

When the emitter terminal of a UJT is open, the resistance between the base terminals is generally high

AC power in a load can be controlled by connecting two SCRs in parallel opposition

To turn off an SCR, reduce anode voltage to zero is done

Regulator – control system that maintains a speed voltage, or other variable within specified limits of a preset level

To turn on a UJT, the forward bias on emitter diode should be more than the peak point voltage

When the temperature increases, the intrinsic stand off ratio is essentially constant

Damping ratio – dimensionless parameter of the second-order characteristic equation

Transfer function is the ratio of two exponential functions of time

A diac is turned on by breakover voltage

LASCR – an SCR whose state is controlled by the light falling upon a silicon semiconductor layer of the device

A diac is simply a triac without gate terminal

Negative-resistance region lies between the peak point and valley point of UJT emitter characteristics

Biomedical electronics – refers to the application of electronic theory, technology, instrumentation, and computing system to biological research and medical problems

UJT exhibits negative resistance region

The UJT operates in negative-resistance region after peak point

SCR is a rectifier constructed of silicon material. Silicon is chosen because of its high temperature and power capabilities

Photovoltaic transduction – a transduction principle used primarily in optical sensors

SCR – is a solid state equivalent of gas-filled triode

The supply voltage is generally less than that of breakover voltage in an SCR

The triac is fundamentally a diac with a gate terminal for controlling the turn-on conditions of the bilateral device in either direction

When the supply voltage exceeds the breakover voltage of an SCR, it starts conducting

Servomechanism – a feedback control system in which the controlled variable is mechanical position

Forward breakover voltage is the voltage above which the SCR enters the conduction region

Root locus – a locus or path of the roots traced out on the s-plane as a parameter is changed

Open-loop control system – a control system in which the output is related to the input by device parameters only

Holding current is that value of current below which the SCR switches from the conduction state to the forward blocking region under stated conditions

Reverse breakdown voltage is equivalent to the zener or avalanche region of the fundamental two-layer semiconductor diode

The required gate triggering current of GTO is 20 mA

Flywheel governor – an automatic speed control device using the centrifugal force on rotating flyweights as the feedback element

Seismic mass is the sensing element of acceleration transducer

GTO is applicable to some areas of counters, pulse generators, multivibrators

Thy – a greek word which means “switch”

1 μs is the typical turn-on time of an SCR

An SCR is a solid state equivalent to Gas-filled triode

The gate of an SCR is positive with respect to its cathode

A normally operated SCR has an anode which is positive with respect to cathode

Hygrometer – a device which can measure humidity directly, with a single sensing element. It is usually calibrated in terms of relative humidity

Bourdon tube – one of the most widely used sensing elements, particularly for pressure ranges higher than 2 MPa

Changing gate voltage can change the angle of conduction in an SCR

An SCR is a member of the thyristor family

An SCR have three pn junction

Sonic, Radiation & Vibrating element are methods used for density sensing

When SCR starts conducting, then gate loses all control

An SCR when turned on has a typical voltage across of 1V

The typical turn-off time of an SCR is about 5 to 30 μs

An SCR is made of Silicon

ECG stands for electrocardiography while EEG stands for electroencephalography

Acceleration transducers are also called accelerometers

When an SCR is compared to a switch, it is considered as a unidirectional switch

When the firing angle of an SCR is increased, its output decreases

When an SCR is OFF, the current in the circuit has small leakage current

An SCR can exercise control over positive or negative half-cycle of ac supply

Gyro is the most widely used attitude and attitude-rate transducersBellow – a sensing element which is typically made from a thin-walled tube formed into deep convolutions and sealed at one end, whose displacement can then be made to act on a transduction element

The voltage across an SCR when it is turned on is about 1 V

Microelectronics

The integrated circuit was invented at Texas instrument in 1958 by Jack Kilby

Inductor component cannot be fabricated into ICs

The purpose of a comparator in op-amps is to produce a change in output when an input voltage equals a reference voltage

The op-amp comparator circuit uses no feedback

Integrated circuit is a complete electronic circuit, containing transistors, diodes, resistor, and capacitors processed on and contained entirely within a single chip of silicon

Planar diffusion – a process used to produce IC semiconductor elements

Very large-scale integration (VLSI) integrated circuit is having more than 1,000 gates

A low power characteristic that does not apply to an op-amp

An integrator op-amp uses capacitor as an element in the feedback path

Large-scale integration (LSI) integrated circuit is having more than 100 gates

The difference in Vbe values is a source of output offset voltage

The voltage gain of differential amplifier equals the AC collector resistance divided by two time the AC resistance of the emitter diodeMedium-scale integration (MSI) integrated circuit is having 10 to 100 gates

Integrated circuit having up to 9 gates is called small-scale integration (SSI)

VCO – exhibits a frequency that can be varied with a dc control voltage

The reason why integrated circuits are divided into digital and linear categories is because they are simply circuits that happen to be constructed integrally and like all circuits, are either switching type of amplifying type

The output of a differentiator is proportional to the rate of change of the input

ICs have advantage over discrete device circuits which is lower cost, high reliability, smaller size

2 Mohm is the typical input resistance of the op-amplifier when measured under open loop

After assembly, the ICs are tested and classified as either military of industrial

Relaxation oscillator operate in the principle of the charging and discharging of a capacitor

ICs for military and space applications are tested in the temperature range of -55C to + 125C

For most commercial and industrial applications, ICs are tested in the temperature range of 0C to +70C

BIFET – an IC op-amp that combines FET’s and bipolar transistor

Heat sink – a mass of metal attached to the case of a transistor to allow the heat to escape more easily

Digital IC processes digital signals

Linear IC processes analog signals

Common-mode signal – a signal that is applied with equal strength to both inputs of a differential amplifier or an op-amp

Prototype – a basic circuit that a designer can modify to get more advanced circuits

Operational amplifier is the most commonly used type of linear IC

741 op amp has been considered as the industry standard of linear ICs

Flat from dc to the critical frequency type of response that characterizes the single pole, low pass filter

An advantage of a shunt regulator over a series type it has an inherent current limiting

The most popular IC used in timing circuits is the 555 timer

The total power dissipated by the operational amplifier is typically 50 mW

In the standard letter-number identification code of operational amplifiers, the letter prefix which normally consists of two or three letters identifies the manufacturer

An op amp circuit that has its output tied directly to the inverting input terminal is called a voltage follower

Most op amp circuits use negative feedback

D is the package suffix code for a plastic dual-in-line for surface mounting on a pc board

25 mA is the approximate short circuit current output of 741 op amp

Discrete unit – a circuit whose components are soldered or otherwise connected mechanically

MPP value in an op-amp is synonymous with output voltage swing, equal to the difference of the two supply voltages, the maximum unclipped peak-to-peak output of an amplifier

Power bandwidth is the highest undistorted frequency out of an op amp for a given slew rate and peak voltage

The summing point in op-amps is a terminal of the op-amp where the input resistors are commonly connected

In terms of circuit component, the term pole refer to a single RC circuit

0.5 V/μs is the slew rate of a 741 operational amplifier

Slew rate specification of an amplifier tells how fast the output voltage can change

80 nA is the typical input bias current of a 741 operational amplifier

The open-loop of an op amp is its voltage gain when there is no negative feedback

The term “monolithic” is derived from a combination of the Greek words “monos” and “lithos” which means single-stone

RC synthesis – a technique used to eliminate the need for inductive elements in monolithic integrated circuits

Most linear ICs are low-power devices with power dissipation ratings of less than 1 W

555 timer – an integrated circuit for both astable and monostable applications

Astable mulivibrator is a square wave clock

In a 5 V level detector circuit the inverting input is connected to +5V

To convert a summing amplifier to an averaging amplifier the ratio of Rf/R must be equal to the reciprocal of the number of inputs

An oscillator is described by unity gain and zero phase shift around the feedback loop

To use a comparator for zero-level detection, the inverting input is connected to ground

In most modern IC op-amps, the 741 requires 2 power supplies

In an op-amp integrator, the feedback path consist of a capacitor

Microwave ICs cover the frequency range from 0.5 to 15 GHz

Monolithic – considered as the fundamental form of IC

Plastic dual-in-line for insertion into sockets has a package suffix code of N and P

The specific application of μA741C op-amp is for commercial

Czochralsky pulling technique is the most common method used for the growth of single crystals for IC fabrication

The charge-coupled device (CCD) is a unique and versatile semiconductor structure invented in 1969 by W.S. Boyle and G.E. Smith

Trip point – the value of the input voltage that switches the output of a comparator or Schmitt trigger

Virtual ground - a type of ground that appears at the inverting input of an op-amp that uses negative feedback

The intel i486 32-bit microprocessor incorporates 1 million transistors on a single chip

In IC op-amps, the input bias current is defined as the average of the two base currents

CMRR means common-mode rejection ratio, the ratio of differential voltage gain to common-mode voltage gain

The typical dimension of a MOSFET in a single IC chip is 1.5 mils x 3 mils

Slew rate – the maximum rate that an output voltage of an op-amp can change

Stray wiring capacitance – the unwanted capacitance between connecting wires and ground

The typical dimension of a BJT in a single IC chip is 4 mils x 6.5 mils

The typical dimension of a diode in a single IC chip is 3 mils x 4.5 mils

Astable multivibrator is equivalent to a relaxation oscillator

If the base 10 is called decimal number system, then base 12 is called duodecimal number system

Planar technology is the principal method used in the fabrication of semiconductor devices for hybrid and monolithic ICs

The gain reduction in operational amplifier is known as roll-off

20 dB per decade (-20 dB/decade) – the rate of gain reduction in operational amplifiers

Compensating capacitor – a capacitor inside an op-amp that prevents oscillations

Integrated circuit – a device that contains its own transistors, resistors and diodes

Slew rate provides a parameter specifying the maximum rate of change of the output when driven by a large step-input signal

The absolute maximum rating for op-amps interval power dissipation is 500 mW

+-30V is the absolute maximum rating for an op-amps differential input voltage

The maximum CMRR of μA741 op-amp is 70 dB

The letter prefix LM identifies National Semiconductor Corporation manufacturer

μA is the letter prefix used by Fairchild semiconductor on their op-amp product

Letter suffix identifies the package style that houses the op amp chip

The package suffix code for ceramic dual-in-line is J

The summing amplifier has two or more inputs, and its output voltage is proportional to the negative of the algebraic sum of its input voltages

When higher power IC’s are needed we can use thin & thick film IC’s

In IC op-amps, one of the most important input characteristics is the input offset current which is defined as the difference between the base currents.

Monolithic IC’s are forms of discrete circuits

COMPUTER PRINCIPLES

William Oughtred – an English mathematician who invented the slide rule in 1622

John Van Neumann – built a computer in 1946 at the Institute of Advance Study (IAS), Princeton, USA, that uses binary numbers and stores information

Computer – an electronic device design to accept data performs prescribed computational and logical operations at high speed and output the result of this operation

UNIVAC – first commercial computer introduced in 1953 that uses valves

ENIAC – the first electronic computer and was completed in 1946

ENIAC was developed at University of Pennsylvania

Presper Eckert and John W. Mauchly constructed ENIAC and UNIVAC

ENIAC consist of 18,000 vacuum tubes

ENIAC could perform 5,000 additions or up to 500 multiplications per second.

Whirlwind I, developed at Massachusetts Institute of Technology is capable of 20,000 operations per second

Computers – refers to the increased use of data conversion circuits as a result of increased application

Control unit is a group of circuits that provides timing and signals to all operation in the computer

ALU – refers to the part of computer that performs mathematical operations

ALU which carries arithmetic and logic operations process binary numbers

Bit is the smallest part of a computer language

A digital word consisting of only four bits is called nibble

Digital electronics – electronics methodology in solving application problems using circuits, in which there are only two possible voltage levels

In digital electronics, there are mainly two possible voltage levels and these make binary number system to be useful in its analysis

8 symbols are used in octal digital number system

Hexadecimal digital number system use 16 symbols

Conversion from binary to octal number system needs a grouping of bits by three

The most practical way of converting hexadecimal numbers to binary is to give each number its four equivalent bits

Boolean algebra – mathematics used in expressing, analyzing, and designing of digital electronic circuits

Karnuagh map is the most commonly used method in simplifying Boolean expression or logical functions. In this method only 1’s and 0’s are entered into the table, while map-entered variable technique includes variables into the table

Quine-McCluskey tabular method – a suitable method in simplying Boolean expression when the system deals with more than six variables

Low level is used to represent logic 1 in a negative logic circuit

High level is used to represent logic 0 in a negative logic circuit

OR is a gate which has two or more low inputs signals to get a low output

OR gate is the logic circuit having two or more inputs but only one output, with high output if any or all inputs are high, with low output only if all inputs are lowOR gate – a logic gate whose output is HIGH when a single HIGH at its input is present

An output of logic zero can be generated by OR gate if all inputs are zero

OR gate – logic gate that generates an output of logic zero if and only if all inputs are zero

A solid state device which only gives a “1” output if all inputs are also “1” is called an AND gate

AND gate – only when all inputs are logic one that this gate can deliver an output of logic one

A solid state logical device which only gives a “1” output if all inputs are “O” is called NOR gate

To cause a three-state buffer to output 0-1 levels, the signal OE must be at logic 1

The rapidly flashing logic probe tip tell you that the logic node being probe has rapidly changing logic activity

Exclusive NOR is a single bit comparator

Sequential refers to the class of logic circuit containing flip-flops

Binary counter is the counter that follows the binary sequence

Multiplexer logic circuit is analogous to a single pole mechanical selector switch

An encoder is an MSI(medium-scale-integrated) circuit that provides an output code that corresponds to which of a set of input line is true

Multiplexing is called the time sharing of one line with multiplex signalsData selector is also called multiplexer

Producing one output pulse for every 10 inputs pulses refers to a function of a decade counter digital IC

Decade counter refers to BCD counter

In a system with MOS devices, the main bus loading factor is likely to be capacitive

When a logic circuit rejects an unwanted signal, this is termed as noise margin

Speed of a logic circuit is normally expressed as propagation delay

Bus is a multi-wire connection between digital circuits

Digitize is the process used to describe analog-to-digital conversion

Time division multiplexing is the process of converting multiple analog input signals sequentially to digital output

A circuit that changes pure binary code into ASCII is called a code converter

The output pulses of the logic pulser can be used to overdrive logic nodes high or low

Circuit used to implement Boolean expression or equations: logic gates/circuits, ditigal circuits, an binary circuits

NAND gate – logic gate whose output is HIGH when one or all its inputs is LOW

NAND gate generates an output of logic zero(LOW) only when all its inputs are logic one(HIGH)

NOR gate – only when all inputs are low thus, this logic gate produces an output of HIGH

NOR gate – a logic gate whose output is logic zero every time one of its inputs goes to logic oneNAND gate – gates with HIGH output level every time one of its inputs goes LOW

XOR logic gate gives an output of logic one if there is and odd number of 1’s at the input

XNOR – logic gate that gives a HIGH output when the input has an even number of 1’s

If the fan out of a logic gate is not enough, a buffer should be used

A buffer multiplies the number of gates a certain output can drive, and this can also be used as a voltage follower, a current amplifier or an isolator

XOR – is considered as a controlled inverter

Universal gate – a logic gate that can be wired to function like any other gate

NOR and NAND – known as universal gates

2 NAND-gates are needed to have an AND function

3 – the number of NAND-gates needed to form an OR-gate

OR function can be achieved by using 2 NOR gates

Binary 0 is the probable output if all inputs of a TTL gate are binary 1

Noise immunity – refers to the ability of a logic circuit to withstand noise superimposed on its input signal

Fan-in – the number of logic gates of the same family that can be connected to the input of a particular gate without degrading the circuit performance

Fan-out – refers to the number of logic gate of the same family that can be driven by a single output of a particular logic gate

RTL – a bipolar logic family that uses resistors at its circuit

DTL – logic family that uses diodes and transistors as its circuit elements. This logic family is more resistant to noise than RTL

HLDTL – a logic circuit family with a supply voltage of 25 V, and are generally used in industry where machinery causes electrical noise and large power line transients to occur

STTL – a variation of transistor-transistor-logic (TTL), wherein transistor’s base and collector junctions are clamped with a Schottky diode

In a transistor-transistor-logic (TTL), if the base collector junction of a transistor is clamped with a Schottky diode it becomes Schottky TTL. The significance of having this diode is it increases the switching speed

ECL bipolar logic circuit is the fastest

CML, CSL and NSL are other name of emitter-coupled logic (ECL)

Of the MOS logic family, CMOS is the fastest

PMOS are generally supplied with a voltage up to 24 V

CMOS are normally supplied with a voltage up to 15 V

By providing a pull-down resistor at the interconnection (PMOS output to CMOS input) you interface PMOS to CMOS

NMOS can be interfaced to CMOS by providing a pull-up resistor

Open-collector configuration – a digital IC whose output transistor has no internal pull-up resistor

In digital ICs, such as buffers and registers, tri-state output configuration is used if they are intended for “busing”

Complementary – the output configuration of most CMOS ICs

In TTL ICs, substrate pnp input configurations gives a high-input impedance at both logic states (HIGH and LOW state)

The purpose of the internal clamping diodes at the input of a logic circuit is to minimize negative ringing effects

In TTL ICs with more than one gate available, sometimes not all gates are used. To handle this unused gates force the output to go HIGH

To handle unused inputs in a logic gate/logic IC pull them down or up, depending on circuit function

Flip-flop is the memory element used in clocked sequential logic circuit

A static memory will store information even when power is not applied to the memory

The reason why more cells can be stored in a given area with dynamic cells is because they are smaller

A magnetic bubble is a solid state memory device, which depends on the magnetic polarization of domains, usually in a garnet type material

Magnetic cores are non-semiconductor devices still used in digital memories

The density of data recorded on magnetic tape is measured in bits per inch

A memory circuit that has 9 address inputs have 512 storage locations

Clock periods are measured from similar points on the clock waveform

Card readers are not a storage device

The function of flip-flop as logic element is it stores binary data

Register is not a type of flip-flop

The higher voltage level in digital gates and flip-flop circuits is Yes or One

Memory word is a byte data stored in a memory location

Accessing is called retrieving data from memory

Applying ultraviolet rays can erase EPROMS

Stack is a segment register which normally access variables in the program

Buffer is a storage device used to accommodate a difference in rate of flow of data or time of occurrence of events when transmitting from one device to another

Latch is a device that stays on once triggered and store one or two conditions as a digital circuit

The typical number of bits per dynamic memory location is 1

Address is an output applied to Read Only Memory (ROM)

ROM is a kind of memory where only manufacturer can store program and has a group of memory locations each permanently storing a word

In shift registers made up of several flip-flops, the clock signal indicates when to shift a bit of data from input of the flip-flop to the output

The duration within it takes to read the content of a memory location after it has been addressed is called access time

A static memory generally contains row and column decoders

ROM is called a memory device which holds fixed set of data in a circuit

Access time – an interval required to address and read out memory word

Counter refers to a circuit that stores pulses and produces an output pulse when specified number of pulses is stored

A dynamic memory will store information as long as power is applied and the memory is refreshed periodicallyFlip-flop – several gates combined to form the basic memory element

An RS flip-flop constructed from NOR-gates would have an undefined output when the inputs R/S combinations are HIGH/HIGH

When a flip-flop is constructed from two NAND-gates, its output will be undefined is the R/S inputs are LOW/LOW

D flip-flop – a flip-flop whose output is always the same as its input. This is sometimes used as a delay element

T flip-flop – flip-flop that changes state every time the input is triggered

Master/slave flip-flop – flip-flop arrangement, such that the first receives its input on the positive edge of a clock pulse, and the other receives its input form the output of the first during the negative edge of the same pulse

Clocked flip-flop – combination of flip-flop, arranged so that they can be triggered at the same time

JK flip-flop, T flip-flop, D flip-flop - A flip-flop without an undefined output state condition whatever the input combination is

Register – group of flip-flops used to store more bits

Sequential access digital memory uses shift register storage circuit

Volatile – memory whose contents are lost when, electrical power is removed

Blowing fuse – can program PROMs

ROM – type of memory wherein the data are permanently stored. Usually the storing of data is done during manufacturing of the component

PROM – a type of ROM that allows data to be written into the device by a programmer. After it has been programmed it cannot be reprogrammed again

PROM, EPROM and EEPROM are semiconductor memory device in which data can be stored after fabrications

EPROM & RPROM can be programmed, and reprogrammed after the old programs are erased usually be an ultraviolet light

EEPROM – a variation of PROM, wherein its stored data can be erased by electrical signal instead of ultraviolet light

The time interval to undertake a refresh operation in a typical dynamic RAM is 2 ms

RAM – semiconductor-based, volatile data storage device that can be written and read randomly

DRAM – Random access memory that needs recharging of capacitors

Dynamic RAM (DRAM) uses capacitor as its data storage element, while static RAM (SRAM) uses flip-flip

Bubble memory – type of memory that is formed by a series of magnetic bubbles at the substrate

Magnetic core – non-semiconductor digital memory device

PROM programmer – a hardware used to program a PROM

Shift register – computer hardware device constructed to perform shifting of its contained data

Serial to parallel register – register wherein data can be serially inputted, while the output can be retrieved in parallel manner

PLA and PAL – digital device similar to that of a ROM and whose internal connections of logic arrays can be programmed by passing high current through fusible links

The difference between a programmable logic array (PLA) and a programmable array logic (PAL) is that with PLA, both OR and AND- gates are programmable, while in PAL, only AND- gate is programmable

Universal logic module (ULM) – a circuit used for selecting a single output from multiple inputs

Multiplexer – another name for universal logic module (ULM)

Demultiplexer – a device/circuit used to separate two or more signals from one line

Ring counter – an electronic counter in which bistable units are cascaded to form a loop

Twisted ring counter is formed when the complemented output of the last stage of a shift register is fed back to the input of the first stage

Decade scaler – a digital circuit that produces logic 1 output pulse for every 10 input pulses

Binary code are converted into ASCII by code converter

Digitize – the technical term used when signals are converted from analog-to-digital

Program is a sequence of instructions that tells the computer machine on how available data shall be processed

Diagram showing procedures that are followed, and actions taken is called flow chart

Machine language is a medium of communication with a computer where programs are written in mnemonics

An assembler, a program which converts instruction written in a source language into machine code, which can be read and acted upon by the computer

Computer program – a detailed step by step of direction telling a computer exactly how to proceed to solve a specific problem or process a specific task

Compiler is a program that translates English-like words of high level language into the machine language of a computer

Compiler is a software that converts a high level language program into machine or assembly language program

The purpose of the fetch cycle in a computer is to obtain instruction

Interpreter refers to a program that translates and then immediately executes statements in a high level language

A macro-instruction is an instruction in a source language that is to be replaced by a defined sequence of instructions in the same source language

Microprocessor – a very high-dense and probably the most versatile integrated circuit used in digital electronics. It is known to function as the central processing unit of most computer applications

Microcomputer – the smallest computer in terms of physical size

Encoder – a logic/digital circuit that generates an output code for every input signal

Binary coded decimal gives each digit of a decimal number with a corresponding binary equivalent

Gray code is considered as minimum change code

ASCII is a 7-bit alphanumeric code that is widely used

Mnemonic – the op-code of a computer instruction

JUMP – an instruction that causes the program to go to another task

LOAD – an instruction that can move data from memory to the accumulator

STORE – an instruction that moves data from accumulator to the memoryFETCH – part of the instruction cycle where the instruction is moved from memory to the instruction register

CLI – an instruction, which means “clear the interrupt mask”

Underflow – refers to a condition wherein the result of an arithmetic operation is more negative than the capacity of the output register

Overflow – refers to a condition wherein the result of an arithmetic operation is more than the capacity of the output register

Machine instructions represented by mnemonics is considered as assembly language

Machine language – the first generation language of instruction, and is considered as the most primitive instruction that can be given to a computer

COBOL, FORTRAN, and ALGOL are examples of high-level language

4GL or 4th generation language – an advanced programming language, more advance than high-level language

Compiler – translator from high-level program to machine instructions

Compiler – translates source program to object program

Assembler – assembly language to machine language translator

Source program – a program in a programming language, as written by the programmer

A source program can run in computers only after translation into a machine code by a compiler. This machine code is referred as the object program

Interpreter – a program that can read a source program in high-level language, translates, and executes the statement in one operation

Program – a sequence of instruction of statements designed to tell the computer how to carry out a particular processing task

The instructions and data in a computer system is referred to as Software

Asynchronous – refers to digital interface in which data characteristics are individually synchronized and may be sent at a time

A network facility used to connect individual similar network segments forming a larger extended network is called repeaters

Parity detector is the circuit that detects bit error in binary characters

Modem – a device that enables users to transmit computer data and fax messages along telephone lines

Modems are device that allow computer to communicate with other computers through telephone lines or radio frequency

Bridges is a network facility used to interconnect distinct network physically

Files in E-mail communication are sent thru attachment

Host – the first recipient in E-mail communication

Network – the interconnections of computers, terminals, and other equipment

Private data network – a network classification that is usually built and owned by a single company or government organization

Public data network – a network that is built and owned by a common carrier

Peer-to-peer – network configuration that let computers share their resources

Hierarchical network – a computer network configuration that makes the host computer manages a network of dependent terminals

Circuit switching – a network switching that creates a dedicated temporary connection between computers in a networkHost – the component that provides control of supporting services for other computers, terminals, or devices in a network

Local area network – it is a type of computer networking technology that is used to connect computers that are located within the same room, building, or complex

File server – it is a fast computer with a large amount of secondary storage, to which all of the other computers in a network have access for data storage & retrieval

Client/server computing – it is also known as cooperative processing that involve using two or more networked computers to perform an application task

Printer server – a type of server that allows multiple users to take advantage of a single printing device

Star – this topology is the most efficient centralized network for a small company

Hub – it is the other term that is used to refer to a central device into which each node of a star network is directly connected

Terminal – it is simply the term that is used to refer to an I/O device that relies entirely on the host computer for processing

Diskless – workstations in a star network that can operate without storage devices

A ring network requires that message travel around the ring to the desired destination

Networks that transmit data across town using electromagnetic signals are called MANs

The process of choosing a terminal on a network to receive data is called selection

A microcomputer attached to a network requires a network interface card

To upload is to send a file to a remote computer

To download is to receive a file from a remote computer

Network protocol – it is the term that is used to describe the conventions of how network components communicate with each other

Network topology – it is the term that is used to describe the form or the shape of a network

Polling is the process of asking each remote terminal, one at a time, if it has data to send

Hierarchical network topology has more than one level of host computer

System Network Architecture – it describes its System Service Control Point (SSCP), Logical Units (LU), and Physical Units (PU) as network addressable units

Networks that include telecommunications are called WANs

A multi-network IBM token ring network is also a star network

Token ring – network topology, where stations are connected to a concentric ring through a ring interface unit (RIU).

A router will decide which route the message or messages should follow through the network

Bridge – used in connecting networks at different sites

Gateway – similar to a bridge, which connects networks at different sites, it connects networks with different protocols

Repeater – used to extend the length of a network or to expand the network

Computer Fundamentals

The decimal system is composes of 10 numerals or symbols

Change in state is toggle

A digital circuit is also referred to as a logic circuit

CMOS means Complementary Metal-Oxide Semiconductor

Microcomputer is the smallest type of computer in terms of their physical size

If each digit of a decimal number is represented by its binary equivalent, the result is a code called binary-coded decimal

BCD code has always 4 bits per number

Logical subtraction is not one of the three basic operations in Boolean algebra

32 bits are required to represent an eight digit decimal number in BCD

The Gray code belongs to a class of codes called the minimum-change codes, in which only one bit in the code group changes when going from one step to the next

The most widely used 7-bit alphanumeric code is the ASCII

A straight binary code takes the complete decimal number and represents it in binary

The number of input combinations will equal 2^N for an N-input truth table

The OR operation result will be 1 if any one or more variables is a 1

AND – a circuit that operates in such a way that its output is high when all its inputs are high

The only input combination that will produce a high at the output of a five-input AND gate is that all inputs should be high

AND gate is equivalent to a NAND gate followed by an inverter

CLC – a circuit with no memory characteristic, and so its output depends only on the current value of its input

Karnaugh map – a graphical device used to convert a truth table to its corresponding logic circuit in a simple, orderly process

The output of an EX-NOR gate when a logic signal and its exact inverse are connected to its input is 1

ULSI – one of the standard levels of complexity of integrated circuits which contains 100,000 and more number of gates

DIP is the most common type of digital IC package

0 to 0.8 V is an acceptable voltage range of a logic 0 for TTL

2 to 5 V is an acceptable voltage range of a logic 1 for TTL

0 to 1.5 V is an acceptable voltage range of a logic 0 for CMOS operating at Vdd = 5 V

3.5 to 5 V is an acceptable voltage range of a logic 1 for CMOS operating at Vdd = 5 V

When the input to a digital IC is left unconnected for TTI ICs it acts like a logic 1

An unconnected input is termed as floating

CMOS integrated circuit response unpredictable, may overheat and be destroyed to a floating input

Shorted signal lines – this type of fault has the same effect as an internal short between IC pins

ROM does not describe a flip-flop circuit

SET = CLEAR = 1 is the normal resting state of the SET and CLEAR inputs in a NAND gate latch

All arithmetic operations take place in the ALU of a computer

A full adder has 3 inputs

A full adder has 2 outputs

A half adder has 2 inputs

The three basic parts of a BCD adder circuit are two 4-bit adders and connection logic

Accumulator is the principal register of an arithmetic logic circuit

Machine language – a computer programming language in which groups of 1s and 0s are used to represent instructions. It is also the only language a computer actually understood

Encoder – a digital circuit that produces an output code depending on which of its inputs is activated

PLD – an IC that contains a large number of interconnected logic functions wherein the user can program the IC for a specific function by selectively breaking the appropriate interconnections

PAL – class of programmable logic device wherein its AND array is programmable while its OR array is hard-wired

Field Programmable Logic Array – class of programmable logic device wherein both its AND and its OR arrays are programmable

2’s complement form – a result which is obtained when a one is added to the least significant bit position of a binary number in the 1’s complement

Astable multivibrator – a digital circuit that oscillates between two unstable output states

Backplane – an electrical connection common to all segments of an LCD

BDC counter – a binary counter that counts from 0000 to 1001 before it recycles

Ring counter – a shift register in which the output of the last flip-flop is connected to the input of the first flip-flop

Reset – a term synonymous with CLEAR in computer systems

Op code – that part of a computer instruction that defines what type of operation the computer is to execute on specified data

Mnemonic – an abbreviation that represents the op code of a computer instruction

Monotonoicity – a property whereby the output of a digital-to-analog converter either increases or stays the same as the input is increases

Optical disk memory – class of mass memory devices that use a laser beam to write and read onto a specified coated disk

Wired-AND – a term used to describe the logic function created when open-collector outputs are tied together

Strobing – a technique often used to eliminate decoding spikes

Glitch – a momentary, narrow, spurious and sharply defined change in volume

A single bit comparator is usually implemented using Exclusive NOR

An equivalent Boolean equation for an exclusive NOR is xy+x’y’

Data storage in a memory is termed as Writing

Data retrieval from a memory is called Reading

A decoder with four inputs can have a maximum of 16 outputs

Another name for a digital multiplexer is data selector

An astable multivibrator has no stable state

A bistable multivibrator has two stable states

A monostable multivibrator has one stable state

A type of multivibrator circuit which generates a square wave of its own is the astable

Don’t care – a situation when a circuit’s output level for a given set of input conditions can be assigned as either a 1 or a 0.

Combinational logic circuit – circuits made up of combinations of logic gates, with no feedback from outputs to inputs

BCD-to-7-segment driver – a digital circuit that takes a 4-bit BCD input and activates the required outputs to display the equivalent decimal digit on a 7-segment display

DC clear – asynchronous flip-flop input used to clear Q immediately to 0

Down counter – a counter that counts from a maximum count downward to zero

Bubble – small circle on the input or output lines of logic circuit symbols which represent inversion of a particular signal

A multiplexer is described by its size through 2^N x 1, where n = number of bits

Hang-up state – a situation in a system where it can never leave or progress to another state

Bubble diagram – a diagram consisting of a set of circles, where each circle contains a number of state within it

Truncated counter – a counter that counts sequentially but does not step through all possible states, it returns to zero after a particular state

Monostable circuit – a circuit that produces an output pulse for a fixed period of time in response to a trigger and then returns to its quiescent state

Tweaking – a small change made in resistance or capacitance to time a circuit precisely

Astable circuit – a square wave oscillator or clock generator

Debouncing circuit – a circuit designed to produce a clean output in response to a switch closure

Duty cycle for repetitive waveform is defined as the ratio of the ON time to the total time

Reset – the state of a flip-flop when Q = 0 and Q’ = 1

Set - the state of a flip-flop when Q = 1 and Q’ = 0

Toggle – a state causing the flip-flop to change or reverse its state

5 flip-flops should be used to realize 32-count capacity

Clock skew – the time difference which results when a clock may not arrive at all flip-flops at precisely the same time

A race condition that exists if a circuit output depends on which of two nearly simultaneous inputs arrive at a point in the circuit first

A one-input JK flip-flop is the T flip-flop

A JK flip-flop can be made to function like a T flip-flop by simply connecting the J and K inputs together as one-input

The one-input RS flip-flop is the D flip-flop

In clock circuits, SWG means Square wave generatorsStrobe – an input signal that can activate or disable a gate

Johnson counter – a ring counter where the output is inverted and tied back to the input

Pseudo-random sequence generator – a circuit that goes through 2^(n-1) states in a random fashion

Strobe – an input that disables multiplexer or demultiplexers when it is HIGH

Blowing – application of excessive current to a fuse in order to open it

An outstanding advantage of LCDs from LEDs is that LCDs essentially acts as a capacitor and consume almost no power

PALASM – a computer language that enables Programmable Array Logic (PAL) users to generate a file that can be used to blow a PAL

Data bus – a type of computer bus which is bidirectional

Simulation table – a table used by a PLD language, such as PALASM, to calculate the expected outputs for a set of inputs

Configurable logic block – a programmable block of logic within a gate array, that contains a flip-flop for storage and also allows the user to specify logic functions on its inputs

Address bus – this type of bus carries the memory address from the computer to the memory

Control bus – this bus carries lines that control the operation of the memory from the microprocessor to the memory

Memory address register – a register which holds the address of the word currently being accessed

Memory data register – a register which holds the data being written into or read out of the addressed memory location

Prototype – a preproduction model of a system built for testing and debugging

Debugging – correcting the faults in a circuit or system

Asynchronous SLC – a sequential logic circuit where the storage elements commonly used are time delay devices (usually gates)

A block added to the combinational logic circuit to form a sequential logic circuit is the memory

The state of the flip-flop before the occurrence of a clock pulse is called as its present state

The state of the flip-flop after the occurrence of a clock pulse is called as its next state

NAND – it is said to be a universal gate because any digital system can be implemented with it

D flip-flop – a flip-flop which follows its input in the next state

An n-bit binary parallel adder requires n full adders in its least design

A magnitude comparator has 2^(2n) entries in the truth table where n = number of comparator bits

An included input terminal in a magnitude comparator IC which is significant when both inputs compared are equal is called as its cascading inputs

In designing a 16 x 1 multiplexer, 4 selection lines are needed

If F = xy + x’y’ Boolean expression is to be implemented using decoders and OR gates, the connection involves 2 to 4 line decoder with 1 OR gate

Handshaking – a system of coordinating I/O between the transmitting and receiving devices

Screen image – an area of memory that holds the ASCII characters that are being displayed on a monitor

UART – an IC that transforms parallel data to serial in the asynchronous format and vice versa

Jump – an instruction that alters the normal course of a program by causing it to jump to another instruction

LOAD – an instruction that causes data to be brought from memory into an accumulator register

FETCH – the portion of an instruction cycle where the instruction is sent from memory to the instruction register

STORE – an instruction that causes data in the accumulator to be moved to the memory or a peripheral register

Underflow – this occurs when the result of an arithmetic operation is a more negative number than the output register can accommodate

Overflow – this occurs when the result of an arithmetic operation is a larger number than the output register can accommodate

2’s complement – a representation of numbers when negative numbers are obtained by complementing their positive equivalent and adding 1

Hypertext mark-up language is the language used in making an internet web page

Benchmark – a program which can be executed on several different computers to compare their speed and performance

Register – a single word memory location used to temporarily hold data during program execution

Trace – refer to the debugging method in which the program is executed one instruction at a time and the register contents can be examined after each step

Console – in a computer system, it is a unit of hardware where the control keys are located

TTL, DTL and ECL, which are frequently used to refer to certain “families” of digital integrated circuits, are actually names of general varieties of electronic circuits used as logic gates, form which, in essence, the building blocks in each series are constructed

In the data sheet of a digital building block, operating speed is typically expressed in terms of propagation delay times for both possible output transitions

The fan out capability of a digital building block depends on the current capability of its output and the current requirement of each input driven by that output, and maybe defined as the number of inputs that one output can transmit to

Noise margin, which is one indication of how likely it is that information communicated between digital building block will be incorrect due to noise, depends on the “safety margin” between the output voltage produced by the transmitting block and input voltage required by the receiving block for each of the two logic state

Typical propagation delay range for modern digital integrated circuit is 1 to 100 nanoseconds

The most commonly used IC package for digital integrated circuits is the DIP plastic

A multiwire connection between digital circuit is usually called a bus

(A + B)’ = A’B’ is a form of De Morgan’s theorem

“Limbo” state of a flip-flop occurs when both outputs are the same

A logic circuit that is triggered by a clock signal is synchronous

BCD counter - another name for a decade counter

Shift register can perform parallel-to-serial data conversion

0 and 1 are used in the binary number system

8 bits are in a byte

In the 7400 Family of TTC Device, Quad 2-input NAND gates has a device number equivalent to 7400

Quad 2-input XOR gates in the 7400 Family of TTL device has a device number equivalent to 7486

A JK Flip-flop will operate in the toggle mode when J = 1, K = 1

A digital circuit test equipment which is a troubleshooting tool that generates a short-duration pulse when activated manually, usually by pressing a button is the Logic pulser

An RS flip-flop will not change in state when R = 0, S = 0

A T flip-flop can be derived by connecting the two inputs of the JK flip-flop together

Radix – the number of digits used by a number system

There are less than 12 gates in an SSI chip

The logic gates in a MSI chip is between 12 to 99 gates

There are 10,000 or more logic gates in a VLSI chip

Assembler is not a part of the hardware organization in an computer

Software – it consists of the instructions and data that the computer hardware manipulates to perform useful work

The most primitive instructions that can be given to a computer are those interpreted directly by the hardware in machine language form

Assembly language – it represents machine instructions by mnemonic names and allows memory addresses and other constants to be represented by symbols rather than bit strings

Compiler – it is needed to translate a high-level program into a sequence of machine instructions that performs the desired task

Text editors and formatters belong to the area of computing known as word processing

The processor or central processing unit is the heart of the computer

Processors with more than two registers for arithmetic and logical operations are classified as general register processors

ROM is a non-volatile device

With a RWM a processor can store data at any address and read back the stored information at any time

The system program use to translate directly an assembly language to machine language is called assembler

SOC – a command to an ADC to start conversion

Speeds of modems are generally classified by the number of bits per second they can transmit

High speed modems transmit between 2400 and 9600 bps

Low speed modems method of modulation is usually frequency shift keying

Low speed modems generally handle data rates between 300 and 2400 bps

The most important memory element which is made of an assembly of logic gates is called flip-flop

Low, high is the normal resting state of the SET and CLEAR inputs in a flip-flop

When a flip-flop is set, Q = 1, Q’ = 0, clear Q = 0, Q’ = 1

Synchronous control inputs and clock input are the two types of inputs that a clocked flip-flop have

The flip-flop can change only when the appropriate clock transition occurs. It is a condition called edge triggered

Set up time – it is the required interval immediately following the active edge of the clock signal during which the control inputs must be held stable

Hold time – it is the required interval immediately following the active edge held of clocks during which the control inputs must be held

The triangle inside the rectangle which is part of the IEEE/ANSI symbology at clock input indicate edge-triggered operation

D type of flip-flop is best suited for synchronous transfer because it requires the fewest interconnections from one flip-flop to the other

The fastest method for transferring data from one register to another is the parallel transfer

The major advantage of serial transfer over parallel transfer is fewer interconnections between registers

Transducer – it converts a non-electrical physical quantity to an electrical quantity

An actuator in the DAC controls a physical variable according to an electrical input signal

Full scale error – the maximum deviation of DAC output from its ideal value, expressed as percentage of full scale

Setting time – the time it takes for the DAC output to settle to within ½ step size of its full scale value when the digital input changes from zero to full scale

Voltage DAC’s are generally slower than current DAC’s because of the response time of the op-amp current-to-voltage converter

The function of the comparator in the ADC is to tell control logic when the DAC output exceeds the analog input

Checksum in ROM’s is a code placed in the last one or two ROM locations that represents the sum of the expected ROM data form all other locations

Interfacing (computer system) – synchronization of digital information transmission between the computer and external I/O devices

An operand address is the address of the data to be operated as the CPU executes the instruction called for by the opcode

CPU device puts data on the data bus during a write operation

Instruction mnemonic means a short abbreviation for the operation

Clock skew – arrival of a clock signal at the clock inputs of different flip-flops at different times as a result of propagation delays

Combinational logic circuit – a circuit made up of combinations of logic gates, with no feedback from outputs to input

DMUX – a logic circuit that depending on the status of its selected inputs will channel its data input to one of several data outputs

An analog memory circuit used to eliminate aperture error is called a track/store amplifier

Logic monitor is not a dynamic test instrument

A translated program in machine language is called an object program