Nowadays, wireless transmissions are increasingly used for all kinds of communications as they save us a lot of infrastructure. In today's article we will show you how to building an FM radio wave transmitter.
An FM transmitter is an electronic device that sends waves through the air that can be received by an FM receiver such as a radio. With an FM transmitter we can build a lot of wireless systems such as wirelessly installing our stereo speakers, creating a radio station in our house, listening to our baby from another room, etc.
The circuit we have to assemble is quite simple. The materials we will need are the following (all of them can be easily found in any electronics shop):
- 2 Transistors 2N2222 (You can also use 2N3904, BC547, BC548)
- 1 Electret microphone
- 2 Electrolytic Capacitors 10uF/25v
- 1 2.2uF/25v Electrolytic Capacitor
- 2 x .1uF/50v Ceramic Capacitors
- 2 x 2.7pF/50v Ceramic Capacitors (can also use 2.5pF)
- 1 Adjustable capacitor 5-60pF (trimmer)
- 2 Resistors 1k
- 1 Resistance 15K
- 1 Resistor 6.8k
- 2 Resistors 10K
- 2 Resistors 4.7K
- 1 Resistor 2.2K
- 1 Resistance 220 Ohm
- 50 cm. Jumper wire 0.51mm diameter (24 AWG)
- 1 Connector + Battery Holder
- 5 Sprats
- 1 Bakelite
- 1 Battery 9V
Once the materials have been obtained, we will have to make the circuit shown in the image on a printed circuit board. To do this, we can use a printed circuit design program such as for example PCB Wizard. This article will help you with the assembly of the printed board.
When placing the components it is important to follow a suitable order that allows us to insert them all comfortably. First we will place the resistors which, as they have a lower height, it is easier to place them when there is still no more solder. Then we place the ceramic capacitors, the trimmer, the springs and the transistors. Finally we connect the electrolytic capacitors and the coil together with the other components.
After building the whole circuit, all that is left is to tune the FM transmitter and the receiver (radio) to the same frequency.. To do this, we tune our radio to an empty frequency on which there is no sound. Then, using a screwdriver, we start turning the trimmer until we hear a kind of whistling sound on the radio. At this point, if we speak into the microphone of the transmitter, our voice should appear on the radio.
Remember that if you have any questions you can ask them in the forum and we will solve it for you without any problem.