Basic Components

At the Atomic Level

• Nucleus made up of Protons (+) and Neutrons (no charge).

• Electrons occupy clouds of probability around nucleus.

• Protons are about 1000 times bigger than electrons.

Conductors, Semiconductors, Insulators

• Properties due to bonding (sharing) of electrons between atoms.– Insulators – strong hold on electrons – not free

to move.– Semiconductors – moderate hold on electrons

but will break loose under right conditions.– Conductors – outer electrons form a sea of

electrons that are free to move within the sea.

Two Fundamentals of Electronics

1. Moving electrons create magnetic fields.

2. Moving or changing magnetic fields cause electrons to move.

Basic Types of Current

• Direct Current (dc)– Electrons move in one direction.

– Can fluctuate (pulse or ripple dc) in magnitude, but still only in one direction.

• Alternating Current (ac)– Electrons reverse direction with some

regularity.

– Constant fluctuation from positive-zero-negative.

Components of Electricity

• Voltage E (Water Pressure)

• Current I (Water Molecules)

• Resistance R (Friction)

Ohm’s Law

• Mathematical relationship between components.

• E = I * R

Alternating Current Defined

• In alternating current (ac), electrons flow back and forth through the conductor with some periodicity.

AC VocabularyCrest

Trough

Amplitude

WaveLength

Power

• Power is the ability to do work.• Work is basically making something move.

– Force over a distanceor

– Pressure over a distance

• If something doesn’t move, there is no work produced.

• Heat produced is also a measure of work.

Power in Electricity

• The force is Voltage.

• The things being moved are electrons.

• Power therefore is Voltage times Current.

• Power is measured in Watts.

Power in DC

• 12 volts pushing 2 amps = 24 W (watts).• 1.5 volts pushing 300 milli amps = 450 milli W.

• This is great for dc, but what about ac when the voltage and current are constantly changing?

Power in ACFinding the Effective Voltage

• The voltage used in power calculations in ac is the equivalent dc voltage value that would do the same amount of work (or heat).

• A simple average of ac voltage is not quite good enough.

• A weighted average called Root Mean Square (RMS) is more accurate.

Important Points about RMS

• RMS is the equivalent value of dc voltage to do the same work.

• RMS is used in Power and Ohm’s Law formulas.

• The RMS voltage is 0.707 times the peak voltage.

Basic Components (and What they Do)

• Resistors– Impede the flow of electrons.

• Coils (inductors)– Store energy in a magnetic field.

• Capacitors– Store energy in an electrostatic field (electrons on one

side, voids on the other).

Resistors

• Values measured in Ohms.– From fractions to millions.– (kilo = 1,000; meg = 1,000,000)

• Ability to handle heat (or power or current).– Physical size (1/4, 1/2, 1, 2, … watt)

Resistors• Material

– Carbon• Most common• High values (Ohms)• High precision• Low power

– Wire• Long, thin wire wound in a coil• Not so common anymore• Low values (Ohms)• Low precision• High power• Lots of inductance (a coil of wire)

Coils (Inductors)

• Values in Henrys.– Single Henry to very small fractions.

– (thousandths and millionths)

• Values depend on.– Diameter of the coil.

– Diameter of the wire.

– Spacing between windings.

– Number of windings.

– Core material.

Capacitors

• Values measured in Farads.– From single to very small fractions.– (millionths and billionths)

• Value depends on:– Surface area of parallel conductive plates.– Space between plates.– Dielectric (material between plates).

Resistance and Reactance

• Resistance is one of the fundamental components of electricity. It inhibits the flow of electrons.

• Inductors and capacitors react differently under dc and ac conditions.– Inductors offer zero resistance in dc environment.– Capacitors offer infinite resistance in dc environment.

• They react quite differently in an ac environment.• The resistance to electron flow in an ac environment

offered by inductors and capacitors is called REACTANCE.

Vcc1

Gnd8

GP52

GP07

GP43

GP16

GP34

GP25

12

F6

75

Out

Gnd

Vcc

4.7K

SW5N.O.

78L05+9V

Ou

t

Gn

d

In

.1uF

SW6

Note: Internal pull-up resistors are used on 12F265 pins

GP0, GP1, GP2, GP4, GP5 External pull-up resistor required on GP3 Protection diodes are internal to K1 - K4 Switchs SW1 - SW4 are internal to K1 - K4

Project T.V. Remote Decoder Circuit

330

1N4001

+5 Voltsto Relays

330

2N3904

+5V

K1

SW1

LED

4.7K

330

2N3904

+5V

K2

SW2

LED

4.7K

330

2N3904

+5V

K3

SW3

LED

4.7K

330

2N3904

+5V

K4

SW4

LED

4.7K