- Here is the circuit diagram of an FM transmitter using the IC UPC1651. UPC1651 is a wide band UHF Silicon MMIC amplifier.
- The IC has a broad frequency response to 1200MHz and power gain up to 19dB.The IC can be operated from 5V DC.
- The audio signals picked by the microphone are fed to the input pin (pin2) of the IC via capacitor C1.
- C1 acts as a noise filter.
- The modulated FM signal will be available at the output pin (pin4) of the IC. Inductor L1 and capacitor C3 forms the necessary LC circuit for creating the oscillations.
- Frequency of the transmitter can be varied by adjusting the capacitor C3.
NOTES:
- The circuit can be assembled on a Vero board.
- Inductor L1 can be made by making 5 turns of 26SWG enameled copper wire on a 4mm diameter plastic former.
- A ¾ meter insulated copper wire can be used as the antenna.
- Do not give more than 6V to the IC.
- Mic M1 can be a condenser microphone.
