So the transmitter and receiver we are making is two separate circuits.A transmitter and receiver circuit.
Transmitter Circuit
In this section of circuit we are using a single transistor(BD 139) which is a medium power transistor.The figure is shown above on left side of the picture.The Bd139 along with the biased resistor which is a 10 kilo ohms,capacitor 100 pf and inductor and capacitor parallel to 10 ohms resistor will generates a high frequency carrier radio frequency wave.
The signal output to the antenna is taken from the collector terminal of the transistor.The antenna propagates the signal to the surrounding areas.The reach of the signal is depending upon the antenna length and power given to the circuit.
Note:
* The power supply we are providing to this circuit is a 12 volt/1 ampere.
* I will recommend only to give the specified power
* Use a heat sink to the transistor as the transistor will heat up after some time.
* The antenna length should not be more than 20 CM.The antenna shape should be in a straight long manner(not spiral,round,spring).
Components Used
1. Transistor - BD 139
2. Resistor - 22 ohms,10 ohms
3. Inductor - 10 micro henry
4. Capacitor - 100 pf, 104 pf
Transmitter & Receiver Components Buy Here
Receiver Circuit
The receiver circuit is the most simplest ever made.It is making use of radio diode rather than any inductor.We are not using any tuning circuit here.The ic used here is a high gain Lm356 amplifier which picks up signals from the 1n34 radio receiver diode and amplifies it to a certain level.
The signal sensitivity/gain can be controlled using a resistor which is feeding to the pin 2 of ic.I use a 56 kilo ohms of resistor.
The output of the Lm356 amplifier is too weak to drive an output like LED or any other audio devices.So the signal is fed to an NPN amplifier transistor BC547, which can drive any loads like LED,relay,buzzer etc.
Note :
* The power supply used is only 3 volt DC.
* If the LED output works continuously change gain resistor(56 kilo ohms)to large value like 100 kilo ohms.
Components Used
1. Radio Diode - 1n 34
2. Ic - Lm 356
3. Resistor - 56 kilo ohms, 1 kilo ohms, 100 ohms
4. Transistor - BC 547
Transmitter Circuit
Transmitter And Receiver Circuit |
Receiver Circuit
Comment below if the circuit is helpful or not working.Also tell me what circuit is needed.
IC - Lm358
R1 - 56 kilo ohms,gain control adjust
R2 - 22 ohms
R3 - 100 ohms
D1,D2 - 1n34 Radio Diode
T1 - BC 547
Antenna - 20 CM long wire
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