FM Radio Circuit

 

FM Radio Circuit

FM Radio Circuit using only two transistor is described in this project.This is a simple FM radio receiver circuit.The circuit is working smoothly.I will show the proof.

How to build a FM Radio Receiver

We use two transistor to achieve this circuit and a very few components less than only six parts is used for making this FM radio circuit.circuityep.com.The output is given to a loud speaker using an amplifier circuit.

The reception of the radio receiver circuit is determined by the length of the antenna. Here i use 20 centimeters of antenna length. Its because there is a radio channel working near by. It is recommended to use the antenna length as large as possible(long wire / dipole antennas).

Components Used

 » Transistor                      - BF494 - 2 Nos

» Inductor                          - 20 Swg thickness

   Copper wire with 5 turns on an air core         Diameter of core - 5 mm

» IC                                       - LM386

» Capacitor Variable         - 30 pf

» Capacitor Electrolytic    - 10 Mfd / 16 v -         2 Nos

» Capacitor Electrolytic    - 100 Mfd / 16 v

» Torroid / Inductor - 100 Micro Henry

» Capacitor Ceramic          - .01 pf

» Resistor                             - 33 kilo ohms ,         3.3 ohms

» Power supply                   - 3 Volts DC

» Speaker                             - 1 Nos

Working

The heart of the circuit is BF494 transistor RF transistor which picks up the RF signals from the surrounding areas.Another BF 494 transistor is used to amplify the weak signals.

This FM radio circuit is so specefic in frequency detection. So that we use 20 swg gauge copper wire inorder to adjust the frequency response we need to adjust the spacing between the windings of wire. The

The capacitor plays a vital role in detecting frequency along with the inductor.I use a 30 pf trimmer capacitor to adjust frequency.

This is a simple circuit for beginners in electronics as we are using all available components here.

The output of the transistor is given to an amplifier ic LM386 through an ac coupling capacitor(filter capacitor .01 pf). The final output is fed to the loud speaker which reproduces the audio signals.

The antenna length is a major factor in detecting signal for such a small and simple circuit.A long wire or dipole antenna is recommened in detecting the rf radio signal.

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