#Transistor fm radio receiver circuit series#

Thus the circuit starts tuning to the nearest frequency.Now adjust the frequency of the circuit by varying the trim pot (variable capacitor) of the tank circuit.Connect the power supply to the circuit.Initially connect the circuit as shown in the figure.To operate the FM Radio circuit following steps are to be followed: Coil is a copper wire wind into fixed number of turns. In this tank circuit coil plays a main role. This is the main part of the circuit as it tunes the radio to the required local frequency. Tank circuit consists of a coil and a variable capacitor. One is connected to the output of the capacitor and the other pin is connected to the ground pin.

The head phone or speaker will have two wires out. Output of the IC is connected to the headphones or Mylar speaker through a capacitor of 220uf 25v rated. These transistors are used for detecting the frequency modulated signals. The variable resistor controls the volume to the input amplifier. Emitter pin is connected to the ground and collector is connected to the supply through a resistor of 22K ohms. Base of transistor Q2 is connected to the tank circuit. Collector is connected to the tank circuit. Base of the transistor is connected to the base of the variable resistor through a capacitor of 0.22uF. It starts conducting only when base gets the required cut off voltage. Note: Also get an idea about How Simple FM Radio Jammer Circuit Works?īF494 is an NPN RF transistor. This amplifies the incoming frequency modulated signal. Sixth pin is the supply pin connected to the supply voltage. Another capacitor is connected to ground pin. Fifth pin is output and is connected to the capacitor which is connected to the speaker or microphone. Inverting pin of the LM386 IC is connected to the ground. The non-inverting pin is connected to the variable resistor of 10KOhms. It has an op-amp internally, which acts as an amplifier. It operates at a supply voltage of 4-12 volts. This is a low voltage audio power amplifier. The FM Radio circuit mainly consists of LM386 IC. The output can be heard using speaker.ĭo you know – How a FM Transmitter Circuit Works? FM Radio Circuit Diagram: FM Radio Circuit Diagram Frequency range of FM signal is 87.5MHz to 108.0MHz. Modulation is nothing but changing the property of the message signal with the respect to the carrier frequency. Data to be transmitted is frequency modulated at the transmission and is demodulated at the receiver side. The main principle of this circuit is to tune the circuit to the nearest frequency using the tank circuit.

The correct frequency range of 87 MHz to 108 MHz can be obtained by adjusting VC2 at the high frequency (108 MHz) and slightly stretching or squeezing together the turns of coil L1 at the end (87 MHz).Radio is the reception of electromagnetic wave through air.

It then should be backed off, very slowly, until oscillation just stops it then should be possible to tune in some stations. To operate the radio receiver, potentiometer VR1 must first be advanced slowly (towards the end of the track connected to battery positive) until, at about the half-way point, a sudden slight increase in background noise will be heard, indicating the onset of oscillation.

#Transistor fm radio receiver circuit series#

The output is suitable for ordinary earphones connected in series to provide an impedance of 64Ω. The value of the rf choke L2 is not critical, anything from 1µH to 10µH being suitable. The “earthy” end (moving vanes and spindle) is connected to the 22pF capacitor C1. The tunning capacitor VC1 is one of the two fm sections of a miniature fm transistor radio with built-in trimmers (VC2).