remote control home appliance usinng rf without microcontroller

7/24/2019 Remote Control Home Appliance Usinng Rf Without Microcontroller

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REMOTE CONTROL HOME APPLIANCE USINNG RF WITHOUT

MICROCONTROLLER

ABSTRACT

The main intention of this project is to control home appliances by using RF

technology, which helps to turn the electrical loads such as light, and fan ON and

OFF through an RF-controlled remote. This is an advanced technology for home

automation as it is used to mae homes very smarter without re!uiring any

switches on the walls.

Nowadays conventional wall switches are located in different parts of a

house and, therefore, to switch on such switches someone has to go there and press

them to turn the loads on or off. "t becomes very difficult for the elderly or

physically handicapped people. #ence, this project is proposed to control home

appliancesthrough an RF. $ith this system, by pressing selected switch of a

remote its corresponding load can be controlled.

The proposed system uses a microcontroller of the %&'( family and a rectified

power supply. )n RF transmitter is connected to the transmitter end with the help

of an encoder device. The push buttons are connected to the microcontroller as

input switches. The commands are sent by the push buttons to the receiver to

control the electrical loads.

)n RF receiver is connected to the receiver end with the help of a decoder device.

The electrical loads are controlled by the TR")* device which is connected to the

microcontroller with the help of an op-isolator to isolate it from the controlling

section.
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The electrical loads are controlled by the RF remote wherein the commands are

sent by the transmitter, and based on these commands- the receiver controls the

electrical loads when corresponding switches are pressed to turn ON and OFF.


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+RO*T /* R"+T"ON

T0R 1"T


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RXR CIRCUIT


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POWER SUPPLY UNIT

"n most of our electronic products or projects we need a power supply forconverting mains )* voltage to a regulated * voltage. For maing a power

supply designing of each and every component is essential. #ere "2m going to

discuss the designing of regulated '3 +ower /upply.

4et2s start with very basic things the choosing of components

Component List :

(. /tep down transformer

5. 3oltage regulator

6. *apacitors


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7. iodes

Vot!"e #e"$!to# :

)s we re!uire a '3 we need 489%&' 3oltage Regulator "*.

9%&' "* Rating :

"nput voltage range 93- 6'3

*urrent rating "c ; ()

Output voltage range 38a


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Re*ti%i*!tion

Rectifier is an electronic circuit consisting of diodes which carries out the

rectification process. Rectification is the process of converting an alternating

voltageor currentinto corresponding direct >dc? !uantity. The input to a rectifier is

ac whereas its output is unidirectional pulsating dc. @sually a full wave rectifier or

a bridge rectifier is used to rectify both the half cycles of the ac supply >full wave

rectification?. Figure below shows a full wave bridge rectifier.

) bridge rectifier consists of four p-n junction diodes connected in the above

shown manner. "n the positive half cycle of the supply the voltageinduced across

the secondary of the electrical transformeri.e. 38N is positive. Therefore point

is positive with respect to F. #ence, diodes 6 and 5 are reversed biased and

diodes ( and 7 are forward biased. The diode 6 and 5 will act as open

switches >practically there is some voltagedrop? and diodes (and7will act as

closed switches and will start conducting. #ence a rectified waveform appears at

the output of the rectifier as shown in the first figure. $hen voltageinduced in

secondary i.e. 38N is negative than 6and 5are forward biased with the other

two reversed biased and a positive voltageappears at the input of the filter.
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)C Fite#!tion

The rectified voltagefrom the rectifier is a pulsating dc voltagehaving very high

ripple content. Aut this is not we want, we want a pure ripple free dc waveform.

#ence a filter is used. ifferent types of filters are used such as capacitorfilter, 4*

filter, *hoe input filter, B type filter. Figure below shows a capacitor filter

connected along the output of the rectifier and the resultant output waveform.

)s the

instantaneous voltage starts increasing the capacitorcharges, it charges till the

waveform reaches its pea value. $hen the instantaneous value starts reducing the

capacitorstarts discharging einput of the

regulator in this case?. #ence, an almost constant dc value having very less ripple

content is obtained.
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Re"$!tion

This is the last bloc in a regulated * power supply. The output voltageor current

will change or fluctuate when there is change in the input from ac mains or due to

change in load current at the output of the regulated power supply or due to other

factors lie temperature changes. This problem can be eliminated by using a

regulator. ) regulator will maintain the output constant even when changes at the

input or any other changes occur. Transistor series regulator, Fi


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transients. "deally the output voltage is given by

Figure below shows the complete circuit of a regulated '3 * power

supply using transformer, bridge rectifier, filter >smoothing? and a fi


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Appi*!tion o% Re"$!te& Po'e# S$pp(

Regulated power supply is the main component of

electrical,electronics and as well as automation equipment.

Mobile phone charger, oscilator, amplier are needed the

regulated power supply

Understanding 780 !" #oltage Regulator

) regulated power supply is very much essential for several electronic devices due

to the semiconductor material employed in them have a fi


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capacitors and resistors with bridge rectifier made up from diodes. From giving an

unchanging voltage supply to building confident that output reaches uninterrupted

to the appliance, the diodes along with capacitors handle elevated efficient signal

conveyal.

)s we have previously taled about that regulated power supply is a device that

mechaniCed on * voltages and also it can uphold its output accurately at a fi


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)s we have made the whole circuit till now to be operated on the '3 * supply, so

we have to use an "* regulator for '3 *. )nd the most generally used "*

regulators get into the maret for '3 * regulation use is 9%&'. /o we are

connecting the similar "* in the circuit as @(.

"* 9%&' is a * regulated "* of '3. This "* is very fle


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rectifier in series in these project so to steady the * output against the variations

in the input * voltage.To obtain a stable output of '3, "* 9%&' is attached with G-

&-G3 along with '&&m) step down transformer as well as with rectifier.To

suppress the oscillation which might generate in the regulator "*, *5 capacitor of

&.( uF value is used. $hen the power supply filter is far away from the regulated

"* capacitor *5 is used.Ripple rejection in the regulator is been improved by *7

capacitor>6'uf? by avoiding the ripple voltage to be amplified at the regulator

output.The output voltage is strengthen and deduction of the output voltage is done

capacitor *6>&.(uF?. To avoid the chance of the input get shorted ' diode is used

to save the regulator. "f ' is not presented in the circuit, the output capacitor can

leave its charge immediately during low impedance course inside the regulators.

LM+,L-.:

The 489%400 series of three terminal positive regulators is available withseveral fiI? pacage, the plastic /O-% >8?

pacage and a chip siCed pacage >%-Aump micro /8? using National2s micro

/8 pacage technology.$ith ade!uate heat sining the regulator can deliver (&&


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8a output current. *urrent limiting is included to limit the pea output current to a

safe value. /afe area protection for the output transistors is provided to limit

internal power dissipation. "f internal power dissipation becomes too high for the

heat sining provided, the thermal shutdown circuit taes over preventing the "*

from overheating.

Ci#*$it )i!"#!m:


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LM+,L-. Ee*t#i*! C/!#!*te#isti*s

4imits in standard typeface are for T ; 5'J*, Aold typeface applies over

&J* to (5'J* for /O-% pacage and K7&J* to %'J* for micro /8 pacage.4imits are guaranteed by production testing or correlation techni!ues using

standard /tatistical Luality *ontrol >/L*? methods.@nless otherwise specified:

"O; 7& m), *" ; &.66 MF, *O ; &.( MF.


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)ir *onditioner $iring The figure 6.9.( show how the connection of the air

conditioner is done.Firstly, this is how and where the wiring of the air conditioner

is done. "t should be tested using the multi meter. The purpose of testing with the

multi meter is to identify which wires need to be bypassed at the switch.There are

two main devices that will be turned on during the switch-on air conditioner

operation. /o the wiring needs to be connected in pairs to two single relays in the

R**/. "t needs two different relays because it will turn on two different devices

which the pair of wiring should not be connected together. The two devices are the

air conditioner fan and the compressor of the air conditioner. Aoth relays will

energiCe during the operation of turning on the air conditioner. )t the same time it

will turn on the air conditioner. "t will allow current to flow through and the air

conditioner will be turned on. Figure 9.6.( shows how the complete connection of

the air conditioner. $ith this connection one channel is complete and ready to

operate.

Fe!t$#es o% LM+,L-.:

i. 489%4&' in micro /8 pacage Output voltage tolerances of ' over

the temperature range

ii. Output current of (&& 8a

iii. "nternal thermal overload protection

iv. Output transistor safe area protection

v. "nternal short circuit current limit

vi. )vailable in plastic TO-D5 and plastic /O-% low profile pacages

vii. No e


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viii. Output voltages of '.&3, G.53, %.53, D.&3, (53, ('3

TR)N/FOR8R

) transformer is a staticelectrical device that transfers energy by inductive

coupling between its winding circuits. ) varying currentin theprimarywinding

creates a varying magnetic fluemf?or voltagein the secondary winding.

Transformers range in siCe from thumbnail-siCed units hidden inside

microphones to units weighing hundreds of tons interconnecting thepower grid. )

wide range of transformer designs are used in electronic and electric power

applications. Transformers are essential for the transmission, distribution, and

utiliCation of electrical energy.
http://en.wikipedia.org/wiki/Static_equilibriumhttp://en.wikipedia.org/wiki/Inductive_couplinghttp://en.wikipedia.org/wiki/Inductive_couplinghttp://en.wikipedia.org/wiki/Electric_currenthttp://en.wikipedia.org/wiki/Magnetic_fluxhttp://en.wikipedia.org/wiki/Magnetic_corehttp://en.wikipedia.org/wiki/Electromagnetic_inductionhttp://en.wikipedia.org/wiki/Electromotive_forcehttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Power_gridhttp://en.wikipedia.org/wiki/Electric_power_transmissionhttp://en.wikipedia.org/wiki/Electric_power_distributionhttp://en.wikipedia.org/wiki/Electric_powerhttp://en.wikipedia.org/wiki/Static_equilibriumhttp://en.wikipedia.org/wiki/Inductive_couplinghttp://en.wikipedia.org/wiki/Inductive_couplinghttp://en.wikipedia.org/wiki/Electric_currenthttp://en.wikipedia.org/wiki/Magnetic_fluxhttp://en.wikipedia.org/wiki/Magnetic_corehttp://en.wikipedia.org/wiki/Electromagnetic_inductionhttp://en.wikipedia.org/wiki/Electromotive_forcehttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Power_gridhttp://en.wikipedia.org/wiki/Electric_power_transmissionhttp://en.wikipedia.org/wiki/Electric_power_distributionhttp://en.wikipedia.org/wiki/Electric_power


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The transformer is based on two principles: first, that an electric current can

produce a magnetic fieldand second that a changing magnetic field within a coil of

wire induces a voltage across the ends of the coil >electromagnetic induction?.

*hanging the current in the primary coil changes the magnetic flu< that is

developed. The changing magnetic flu< induces a voltage in the secondary coil.

Referring to the basic transformer in the figure below, current passing

through the primary coil creates a magnetic field. The primary and secondary coils

are wrapped around a core of very high magnetic permeability, such as iron, so that

most of the magnetic flu< passes through both the primary and secondary coils.

"f a load is connected to the secondary winding, the load current and voltage

will be in the directions indicated, given the primary current and voltage in the

directions indicated >each will be )* in practice?.

The ideal transformer model assumes that all flu< generated by the primary

winding lins all the turns of every winding, including itself. "n practice, some fluW(, pin G? and two active-low control lines >W5), pin 7 and W5A, pin '?.

Thus, the 974/(6% will only be in its PdecodingP mode if W( is at logic P(P and W5)

and W5A are at logic P&P. The 974/(6%, whose generic product name is P6-to-% 4ine

ecoderH8ultiple


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priority, and the output of the encoder will depend on this prioritiCed input. Table 5

shows the truth table for the 974/(7%. Note that & and W/ are output pins while

( is a control pin >input?.

Table 5. Truth Table for the 974/(7%, an %-to-6 4ine +riority ncoder

( 9 G ' 7 6 5 ( & )5 )( )& & W/

(

&

&

&

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$ight%&mitting 'iode ($&')*

) light-emitting diode >4? is a semiconductordevice that emits visible

light when an electric currentpasses through it. The light is not particularly bright,

but in most 4s it is monochromatic, occurring at a single wavelength. The

output from an 4 can range from red >at a wavelength of approabout 7&& nanometers?. /ome 4s emit infrared > "R?

energy >%6& nanometers or longer?U such a device is nown as an infrared-emitting

diode>"R?.
http://searchcio-midmarket.techtarget.com/definition/semiconductorhttp://searchcio-midmarket.techtarget.com/definition/currenthttp://searchnetworking.techtarget.com/definition/wavelengthhttp://searchnetworking.techtarget.com/definition/infrared-radiationhttp://searchcio-midmarket.techtarget.com/definition/semiconductorhttp://searchcio-midmarket.techtarget.com/definition/currenthttp://searchnetworking.techtarget.com/definition/wavelengthhttp://searchnetworking.techtarget.com/definition/infrared-radiation


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)i!"#!m:

LE) )is*#iption:

)n 4 or "R consists of two elements of processed material called P-

type semiconductors and&-type semiconductors. These two elements are placed in

direct contact, forming a region called theP-& 'unction. "n this respect, the 4 or

"R resembles most other diodetypes, but there are important differences. The

4 or "R has a transparent pacage, allowing visible or "R energy to pass

through. )lso, the 4 or "R has a large +N-junction area whose shape is

tailored to the application.
http://searchcio-midmarket.techtarget.com/definition/diodehttp://searchcio-midmarket.techtarget.com/definition/diode


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Aenefits of 4s and "Rs, compared with incandescent and fluorescent

illuminating devices, include:

Lo' po'e# #e0$i#ement: 8ost types can be operated with battery power

supplies.

Hi"/ e%%i*ien*(: 8ost of the power supplied to an 4 or "R is

converted into radiation in the desired form, with minimal heat production.

Lon" i%e: $hen properly installed, an 4 or "R can function for

decades.

T(pi*! !ppi*!tions in*$&e:

In&i*!to# i"/ts: These can be two-state >i.e., onHoff?, bar-graph, or

alphabetic-numeric readouts.

LC) p!ne 1!*2i"/tin":/pecialiCed white 4s are used in flat-panel

computer displays.

Fi1e# opti* &!t! t#!nsmission: ase of modulation allows wide

communicationsbandwidthwith minimal noise, resulting in high speed and

accuracy.

Remote *ont#o:8ost home-entertainment XremotesX use "Rs to transmit

data to the main unit.

Optoiso!to#:/tages in an electronic system can be connected together

without unwanted interaction.
http://searchnetworking.techtarget.com/definition/modulationhttp://searchenterprisewan.techtarget.com/definition/bandwidthhttp://searchnetworking.techtarget.com/definition/optoisolatorhttp://searchnetworking.techtarget.com/definition/modulationhttp://searchenterprisewan.techtarget.com/definition/bandwidthhttp://searchnetworking.techtarget.com/definition/optoisolator


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Re!(:

) #e!(is an electricallyoperated switch. 8any relays use an electromagnetto operate a switching mechanism mechanically, but other operating principles are

also used. Relays are used where it is necessary to control a circuit by a low-power

signal >with complete electrical isolation between control and controlled circuits?,

or where several circuits must be controlled by one signal. The first relays were

used in long distance telegraphcircuits, repeating the signal coming in from one

circuit and re-transmitting it to another. Relays were used e


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) simple electromagnetic relay consists of a coilof wire wrapped around a

soft iron core, an iron yoe which provides a low reluctancepath for magnetic

fluthere are two in

the relay pictured?. The armature is hinged to the yoe and mechanically lined to

one or more sets of moving contacts.

"t is held in place by a springso that when the relay is de-energiCed there is

an air gap in the magnetic circuit. "n this condition, one of the two sets of contacts

in the relay pictured is closed, and the other set is open. Other relays may havemore or fewer sets of contacts depending on their function. The relay in the picture

also has a wire connecting the armature to the yoe. This ensures continuity of the

circuit between the moving contacts on the armature, and the circuit trac on the

printed circuit board>+*A? via the yoe, which is soldered to the +*A.

$hen an electric currentis passed through the coil it generates a magnetic

field that activates the armature, and the conse!uent movement of the movable

contact>s? either maes or breas >depending upon construction? a connection with

a fi


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then the movement opens the contacts and breas the connection, and vice versa if

the contacts were open. $hen the current to the coil is switched off, the armature is

returned by a force, appro)*?, a small copper Xshading ringX can be

crimped to the end of the solenoid, creating a small out-of-phase current which

increases the minimum pull on the armature during the )* cycle.Q(

) solid-state relay uses a thyristor or other solid-state switching device,

activated by the control signal, to switch the controlled load, instead of a solenoid.

)n optocoupler>a light-emitting diode>4? coupled with aphoto transistor? can

be used to isolate control and controlled circuits.

T(pes o% Re!(:
http://en.wikipedia.org/wiki/Relay#Undesired_arcinghttp://en.wikipedia.org/wiki/Direct_currenthttp://en.wikipedia.org/wiki/Diodehttp://en.wikipedia.org/wiki/Voltage_spikehttp://en.wikipedia.org/wiki/Semiconductorhttp://en.wikipedia.org/wiki/Snubberhttp://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Relay#cite_note-1http://en.wikipedia.org/wiki/Solid-state_relayhttp://en.wikipedia.org/wiki/Thyristorhttp://en.wikipedia.org/wiki/Optocouplerhttp://en.wikipedia.org/wiki/Light-emitting_diodehttp://en.wikipedia.org/wiki/Photo_transistorhttp://en.wikipedia.org/wiki/Relay#Undesired_arcinghttp://en.wikipedia.org/wiki/Direct_currenthttp://en.wikipedia.org/wiki/Diodehttp://en.wikipedia.org/wiki/Voltage_spikehttp://en.wikipedia.org/wiki/Semiconductorhttp://en.wikipedia.org/wiki/Snubberhttp://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Relay#cite_note-1http://en.wikipedia.org/wiki/Solid-state_relayhttp://en.wikipedia.org/wiki/Thyristorhttp://en.wikipedia.org/wiki/Optocouplerhttp://en.wikipedia.org/wiki/Light-emitting_diodehttp://en.wikipedia.org/wiki/Photo_transistor


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4atching relay

Read relay

8ercury-wetted relay

8ercury relay

+olariCed relay 8achine tool relay

Ratchet relay

*oa


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distinguished as Xearly-maeX or NOEM, which means that the contacts

close before the button or switch is fully engaged.

Normally-closed >NC? contacts disconnect the circuit when the relay is

activatedU the circuit is connected when the relay is inactive. "t is also called

a Fo#m Bcontact or XbreaX contact. NCcontacts may also be distinguished

as Xlate-breaX or NCLB, which means that the contacts stay closed until the

button or switch is fully disengaged.

*hange-over >CO?, or double-throw >)T?, contacts control two circuits: one

normally-open contact and one normally-closed contact with a common

terminal. "t is also called a Fo#m Ccontact or XtransferX contact >Xbrea

before maeX?. "f this type of contact utiliCes a Xmae before breaX

functionality, then it is called a Fo#m )contact.

The following designations are commonly encountered:

SPST= /ingle +ole /ingle Throw. These have two terminals which can be

connected or disconnected. "ncluding two for the coil, such a relay has four

terminals in total. "t is ambiguous whether the pole is normally open or

normally closed. The terminology X/+NOX and X/+N*X is sometimes used

to resolve the ambiguity.

SP)T= /ingle +ole ouble Throw. ) common terminal connects to either

of two others. "ncluding two for the coil, such a relay has five terminals in

total.

)PST= ouble +ole /ingle Throw. These have two pairs of terminals.

!uivalent to two /+/T switches or relays actuated by a single coil.


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"ncluding two for the coil, such a relay has si< terminals in total. The poles

may be Form ) or Form A >or one of each?.

)P)T= ouble +ole ouble Throw. These have two rows of change-over

terminals. !uivalent to two /+T switches or relays actuated by a single

coil. /uch a relay has eight terminals, including the coil.

Appi*!tions:

Relays are used for:

)mplifying a digital signal, switching a large amount of power with a small

operating power. /ome special cases are:

o ) telegraph relay, repeating a wea signal received at the end of a

long wire


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o *ontrolling a high-voltage circuit with a low-voltage signal, as in

some types of modemsor audio amplifiers,

o *ontrolling a high-currentcircuit with a low-current signal, as in the

startersolenoidof an automobile.

etecting and isolating faults on transmission and distribution lines by

opening and closing circuit breaers >protection relays?,/witching to a

standby power supply.
http://en.wikipedia.org/wiki/Modemhttp://en.wikipedia.org/wiki/Electric_currenthttp://en.wikipedia.org/wiki/Starter_motorhttp://en.wikipedia.org/wiki/Solenoidhttp://en.wikipedia.org/wiki/Automobilehttp://en.wikipedia.org/wiki/Circuit_breakerhttp://en.wikipedia.org/wiki/Modemhttp://en.wikipedia.org/wiki/Electric_currenthttp://en.wikipedia.org/wiki/Starter_motorhttp://en.wikipedia.org/wiki/Solenoidhttp://en.wikipedia.org/wiki/Automobilehttp://en.wikipedia.org/wiki/Circuit_breaker


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RF T#!nsmitte#:

) radio transmitteris an electronicdevicewhich, when connected to

an antenna, produces an electromagneticsignalsuch as in radioand

televisionbroadcasting, two way communications or radar. #eating devices, such

as a microwave oven, although of similar design, are not usually called

transmitters, in that they use the electromagnetic energy locally rather than

transmitting it to another location. ) radio transmitter design has to meet certain

re!uirements. These include the fre!uency of operation, the type of modulation, the

stability and purity of the resulting signal, the efficiency of power use, and the

power level re!uired to meet the system design objectives.Q(#igh-power

transmitters may have additional constraints with respect to radiation safety,

generation of 0-rays, and protection from high voltages.

Typically a transmitter design includes generation of a carrier signal, which

is normally sinusoidal, optionally one or more fre!uency multiplication stages, a

modulator, a power amplifier, and a filter and matching networ to connect to an

antenna. ) very simple transmitter might contain only a continuously running

oscillator coupled to some antenna system. 8ore elaborate transmitters allow

better control over the modulation of the emitted signal and improve the stability of

the transmitted fre!uency. For e8O+)? configuration inserts an amplifier stage between the oscillator and the

antenna. This prevents changes in the loading presented by the antenna from

altering the fre!uency of the oscillator.
http://en.wikipedia.org/wiki/Radio_transmitterhttp://en.wikipedia.org/wiki/Electronicshttp://en.wikipedia.org/wiki/Machinehttp://en.wikipedia.org/wiki/Antenna_(electronics)http://en.wikipedia.org/wiki/Electromagnetic_radiationhttp://en.wikipedia.org/wiki/Signalling_(telecommunication)http://en.wikipedia.org/wiki/Radiohttp://en.wikipedia.org/wiki/Televisionhttp://en.wikipedia.org/wiki/Radarhttp://en.wikipedia.org/wiki/Microwave_ovenhttp://en.wikipedia.org/wiki/Frequency_allocationhttp://en.wikipedia.org/wiki/Modulationhttp://en.wikipedia.org/wiki/Radio_transmitter_design#cite_note-1http://en.wikipedia.org/wiki/Radio_transmitterhttp://en.wikipedia.org/wiki/Electronicshttp://en.wikipedia.org/wiki/Machinehttp://en.wikipedia.org/wiki/Antenna_(electronics)http://en.wikipedia.org/wiki/Electromagnetic_radiationhttp://en.wikipedia.org/wiki/Signalling_(telecommunication)http://en.wikipedia.org/wiki/Radiohttp://en.wikipedia.org/wiki/Televisionhttp://en.wikipedia.org/wiki/Radarhttp://en.wikipedia.org/wiki/Microwave_ovenhttp://en.wikipedia.org/wiki/Frequency_allocationhttp://en.wikipedia.org/wiki/Modulationhttp://en.wikipedia.org/wiki/Radio_transmitter_design#cite_note-1


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Mo&e o% F#e0$en*(:

Fi


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operate the oscillator at the final output fre!uency. For better fre!uency stability, it

was common to multiply the fre!uency of the oscillator up to the final, re!uired

fre!uency. This was accommodated by allocating the short wave amateur and

marine bands in harmonically related fre!uencies such as 6.', 9, (7 and 5% 8#C.

Thus one crystal or 3FO could cover several bands. "n simple e!uipment this

approach is still used occasionally.

"f the output of an amplifier stage is simply tuned to a multiple of the fre!uency

with which the stage is driven, the stage will give a large harmonic output. 8any

transmitters have used this simple approach successfully. #owever these more

comple< circuits will do a better job. "n a push-push stage, the output will only

contain even harmonics. This is because the currents which would generate the

fundamental and the odd harmonics in this circuit are canceled by the second

device. "n a push-pull stage, the output will contain only odd harmonics because of

the canceling effect.

Mo&$!tion:

The tas of a transmitter is to convey some form of information using a radio

signal >carrier wave? which has been modulated to carry the intelligence. The RF

generator in a microwave oven, electro surgery, and induction heatingare similar

in design to transmitters, but usually not considered as such in that they do not

intentionally produce a signal that will travel to a distant point. /uch RF devices

are re!uired by law to operate in an "/8 bandwhere interference to radio

communications will not occur. $here communications is the object, one or more

of the following methods of incorporating the desired signal into the radio wave is

used.
http://en.wikipedia.org/wiki/Microwave_ovenhttp://en.wikipedia.org/wiki/Electrosurgeryhttp://en.wikipedia.org/wiki/Induction_heatinghttp://en.wikipedia.org/wiki/ISM_bandhttp://en.wikipedia.org/wiki/Microwave_ovenhttp://en.wikipedia.org/wiki/Electrosurgeryhttp://en.wikipedia.org/wiki/Induction_heatinghttp://en.wikipedia.org/wiki/ISM_band


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AM mo&es:

$hen the amplitude of a radio fre!uency wave is varied in amplitude in a manner

which follows the modulating signal, usually voice, video or data, we

have )mplitude modulation>)8?.

Lo' e3e !n& /i"/ e3e:

"n low level modulation a small audiostage is used to modulatea low power stage.

The output of this stage is then amplified using a linearRF amplifier. The great

disadvantage of this system is that the amplifier chain is less efficient, because it

has to be linear to preserve the modulation. #ence high efficiency class *

amplifiers cannot be employed, unless a oherty amplifier, R >nvelope

limination and Restoration? or other methods of predistortion or negative

feedbacare used. #igh level modulation uses class * amplifiers in a broadcast

)8 transmitter and only the final stage or final two stages are modulated, and all

the earlier stages can be driven at a constant level. $hen modulation is applied to

the plate of the final tube, a large audio amplifier is needed for the modulation

stage, e!ual to (H5 of the * input power of the modulated stage. Traditionally the

modulation is applied using a large audio transformer. #owever many different

circuits have been used for high level )8 modulation. /ee )mplitude 8odulation.

Types of )8 modulators:

) wide range of different circuits have been used for )8. $hile it is perfectly

possible to create good designs using solid-state electronics, valved>tube? circuits

are shown here. "n general, valves are able to easily yield RF powers far in e


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below 6 8#C use solid state circuits, but higher power stations above 6 8#C still

use valves.

+late )8 modulators:

)node modulation using a transformer. The valve anode sees the vector sum of

anode volts and audio voltage.

) series modulated stage. "n modern transmitters the series regulator will

use +$8switching for high efficiency. #istorically the series regulator would

have been a tube in analog mode.

#igh level plate modulation consists of varying the voltage on the plate >anode? of

the valve so that it swings from nearly Cero to double the resting value. This will

produce (&& modulation and can be done by inserting a transformer in series

with the high voltage supply to the anode so that the vector sum of the two sources,
http://en.wikipedia.org/wiki/Pulse-width_modulationhttp://en.wikipedia.org/wiki/Pulse-width_modulation


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>* and audio? will be applied. ) disadvantage is the siCe, weight and cost of the

transformer as well as its limited audio fre!uency response, especially for very

powerful transmitters.

)lternatively a series regulator can be inserted between the * supply and the

anode. The * supply provides twice the normal voltage the anode sees. The

regulator can allow none or all of the voltage to pass, or any intermediate value.

The audio input operates the regulator in such a way as to produce the

instantaneous anode voltage needed to reproduce the modulation envelope. )n

advantage of the series regulator is that it can set the anode voltage to any desired

value. Thus the power output of the transmitter can be easily adjusted, allowing the

use of ynamic *arrier *ontrol. The use of +8 switching regulators maes this

system very efficient, whereas the original analog regulators were very inefficient

and also non linear. /eries +8 modulators are used in solid state transmitters

also, but the circuits are somewhat more comple


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/creen )8 modulator. Wrid bias not shown

@nder carrier conditions >no audio? the stage will be a simple RF amplifier where

the screen voltage is set lower than normal to limit the RF output to about 5' of

full power. $hen the stage is modulated the screen potential changes and so alters

the gain of the stage. "t taes much less audio power to modulate the screen, but

final stage efficiency is only about 7&, compared to %& with plate modulation.

For this reason screen modulation was used only in low power transmitters and is

now effectively obsolete.

)8 related modes:

/ingle-sideband modulation:

//A, or //A-)8 single-sideband full carrier modulation, is very similar to single-

sideband suppressed carrier modulation>//A-/*?"t is used where it is necessary to

receive the audio on an )8 receiver, while using less bandwidth than with double

sideband )8. ue to high distortion, it is seldom used. ither //A-)8 or //A-

/* are produced by the following methods.

Filter method:

@sing a balanced mi


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+hasing method:

+hasing method of //A generation

The phasing method for the generation of single sideband signals uses a networ

which imposes a constant D&J phase shift on audio signals over the audio range ofinterest. This was difficult with analog methods but with /+is very simple.

These audio outputs are each mi


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8orse:

8orse codeis usually sent using on-off eying of an unmodulated carrier

>*ontinuous wave?. No special modulator is re!uired.

This interrupted carrier may be analyCed as an )8-modulated carrier. On-off

eying produces sidebands, as etrue Fre!uency modulation? is where the fre!uency of an oscillatoris

altered to impose the modulation upon the carrier wave. This can be done by using

a voltage-controlled capacitor >3aricapdiode? in a crystal-controlled oscillator

or fre!uency synthesiser. The fre!uency of the oscillator is then multiplied up

using a fre!uency multiplier stage, or is translated upwards using a mi


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"ndirect F8:

"ndirect F8 solid state circuit.

"ndirect F8 employs a varicap diode to impose a phase shift >which is voltage-

controlled? in a tuned circuit that is fed with a plain carrier. This is termedphase

modulation. "n some indirect F8 solid state circuits, an RF drive is applied to the

base of a transistor. The tan circuit >4*?, connected to the collector via a

capacitor, contains a pair of varicapdiodes. )s the voltage applied to the varicaps

is changed, the phase shift of the output will change.

+hase modulation is mathematically e!uivalent to direct Fre!uency modulation

with a GdAHoctave high-pass filterapplied to the modulating signal. This high-pass

effect can be e


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igital modes:

Transmission of digital data is becoming more and more important. igital

information can be transmitted by )8 and F8 modulation, but often digital

modulation consists of comple< forms of modulation using aspects of both )8 and

F8. *OF8is used for R8broadcasts. The transmitted signal consists of

multiple carriers each modulated in both amplitude and phase. This allows very

high bit rates and maes very efficient use of bandwidth. igital or pulse methods

also are used to transmit voice as in cell phones, or video as in terrestrial T3

broadcasting. arly teradio fre!uency module? is a >usually? small electronic device used

to transmit andHor receive radio signals between two devices. "n an embedded

systemit is often desirable to communicate with another device wirelessly. This

wireless communication may be accomplished through optical communicationor

through radiofre!uency >RF? communication. For many applications the medium

of choice is RF since it does not re!uire line of sight. RF communications

incorporate a transmitterandHor receiver.

RF modules are widely used in electronic design owing to the difficulty of

designing radio circuitry. Wood electronic radio design is notoriously compleF**?. For these

reasons, design engineers will often design a circuit for an application which

re!uires radio communication and then Xdrop inX a pre-made radio module rather

than attempt a discretedesign, saving time and money on development.

RF modules are most often used in medium and low volume products for

consumer applications such as garage door openers, wireless alarm

systems, industrial remote controls, smart sensor applications, and wireless home

automation systems. They are sometimes used to replace older infra

redcommunication designs as they have the advantage of not re!uiring line-of-

sight operation.

/everal carrier fre!uencies are commonly used in commercially-available

RF modules, including those in the industrial, scientific and medical >"/8? radio

bandssuch as 766.D5 8#C, D(' 8#C, and 57&& 8#C. These fre!uencies are used

because of national and international regulations governing the used of radio for

communication. /hort Range evicesmay also use fre!uencies available for

unlicensed such as 6(' 8#C and %G% 8#C.

The RF module, as the name suggests, operates at Radio Fre!uency. The

corresponding fre!uency range varies between 6& #C Z 6&& W#C. "n this RFsystem, the digital data is represented as variations in the amplitude of carrier

wave. This ind of modulation is nown as )mplitude /hift 1eying >)/1?.
https://en.wikipedia.org/wiki/Conformance_testinghttps://en.wikipedia.org/wiki/Standardizationhttps://en.wikipedia.org/wiki/ETSIhttps://en.wikipedia.org/wiki/Federal_Communications_Commissionhttps://en.wikipedia.org/wiki/Discrete_devicehttps://en.wikipedia.org/wiki/Remote_controlshttps://en.wikipedia.org/wiki/Home_automationhttps://en.wikipedia.org/wiki/Home_automationhttps://en.wikipedia.org/wiki/Infra_redhttps://en.wikipedia.org/wiki/Infra_redhttps://en.wikipedia.org/wiki/ISM_bandhttps://en.wikipedia.org/wiki/ISM_bandhttps://en.wikipedia.org/wiki/Short_Range_Deviceshttps://en.wikipedia.org/wiki/Conformance_testinghttps://en.wikipedia.org/wiki/Standardizationhttps://en.wikipedia.org/wiki/ETSIhttps://en.wikipedia.org/wiki/Federal_Communications_Commissionhttps://en.wikipedia.org/wiki/Discrete_devicehttps://en.wikipedia.org/wiki/Remote_controlshttps://en.wikipedia.org/wiki/Home_automationhttps://en.wikipedia.org/wiki/Home_automationhttps://en.wikipedia.org/wiki/Infra_redhttps://en.wikipedia.org/wiki/Infra_redhttps://en.wikipedia.org/wiki/ISM_bandhttps://en.wikipedia.org/wiki/ISM_bandhttps://en.wikipedia.org/wiki/Short_Range_Devices


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Transmission through RF is better than "R >infrared? because of many reasons.

Firstly, signals through RF can travel through larger distances maing it suitable

for long range applications. )lso, while "R mostly operates in line-of-sight mode,

RF signals can travel even when there is an obstruction between transmitter Z

receiver. Ne


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) wireless radio fre!uency >RF? transmitter and receiver can be easily made

using #T(5ecoder, #T(5ncoder and )/1 RF 8odule. $ireless

transmission can be done by using 7668hC or 6('8#C )/1 RF Transmitter and

Receiver modules. "n these modules digital data is represented by different

amplitudes of the carrier wave, hence this modulation is nown as )mplitude /hift

1eying >)/1?. Radio Fre!uency >RF? transmission is more strong and reliable

than "nfrared >"R? transmission due to following reasons :
https://electrosome.com/ht12d-decoder-ic-remote-control-systems/https://electrosome.com/ht12e-encoder-ic-remote-control-systems/https://electrosome.com/ht12d-decoder-ic-remote-control-systems/https://electrosome.com/ht12e-encoder-ic-remote-control-systems/


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Radio Fre!uency signals can travel longer distances than "nfrared.

Only line of sight communication is possible through "nfrared while radio

fre!uency signals can be transmitted even when there is obstacles.

"nfrared signals will get interfeared by other "R sources but signals on one

fre!uency band in RF will not interfeared by other fre!uency RF signals.

+ransmitter "ircuit 'iagram


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AS( #) ransmitter

#T(5 ncoder "* will convert the 7 bit parallel data given to pins & = 6 to

serial data and will be available at O@T. This output serial data is given to )/1

RF Transmitter. )ddress inputs )& = )9 can be used to provide data security

and can be connected to WN >4ogic IRO? or left open >4ogic ON?. /tatus of

these )ddress pins should match with status of address pins in the receiver for the

transmission of the data. ata will be transmitted only when the Transmit nable

pin >T? is 4O$. (.(8[ resistor will provide the necessary e


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AS( #) #eceiver

)/1 RF Receiver receives the data transmitted using )/1 RF Transmitter. #T(5

decoder will convert the received serial data to 7 bit parallel data & = 6. The


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status of these address pins )&-)9 should match with status of address pin in the

#T(5 at the transmitter for the transmission of data. The 4 connected to the

above circuit glows when valid data transmission occurs from transmitter to

receiver. '(1[ resistor will provide the necessary resistance re!uired for the

internal oscillator of the #T(5.

Fe!t$#es

"nput +ower supply - ' 3olts

*ompatible for Aoth RF 766H 6(' 8hC

Renesas controller Aased

Rdy to "nterface upto % Ait ata

@)RT TT4 oHp - Aaud Rate - 7%&&


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+acage "ncludes with RF T< R

remote control home appliance usinng rf without microcontroller

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