Building an FM radio transmitter is an excellent first electronics project. You can use this circuit to transmit any audio signal via FM radio. The circuit is relatively simple to build. The easiest way to construct this circuit is to use a solderless breadboard. While the distance your signal will travel is much less than that of a signal generated from an industrial transmitter, you still have the satisfaction of using the same kind of technology as major radio stations.
Place the IC socket, resistors and capacitors in the breadboard. Refer to the schematic in Reference 1 for all connections.
Place the IC into the IC socket.
Place the oscillator, RF coil and inductor in the breadboard.
Place the jumper wires onto the breadboard to make additional connections required by the circuit.
Snap the batteries into the battery holder.
Connect the battery holder wires to the breadboard.
Cut a length of wire and connect it to the breadboard to serve as an antenna.
If you decide to boost the output power of your transmitter, be aware that unlicensed FM radio broadcasts are illegal in the United States. Keep the broadcast area on your own property.
Tips and warnings
- If you decide to boost the output power of your transmitter, be aware that unlicensed FM radio broadcasts are illegal in the United States. Keep the broadcast area on your own property.
Things you need
- Solderless breadboard
- DIP-18 IC socket
- 2 metal film resistors, 47K 1%
- 2 metal film resistors, 27K 1%
- 150K 1% metal film resistor
- 5.6K 1% metal film resistor
- 4 metal film resistors, 270 1%
- 4 gold audio capacitors, 10uF/50V
- 4 ceramic capacitors, 1nF
- 2 Mylar capacitors, 1nF
- 220pF ceramic capacitor
- BA1404 IC
- 38KHz crystal oscillator
- 3.5T variable precision RF coil
- 10uH inductor
- Jumper wires
- 2 AA batteries
- Battery holder
- Wire cutters
- No. 20 uninsulated wire