How to make an FM radio transmitter

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.

Homemade radio 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)
- Screws
- 1 Connector + Battery Holder
- 5 Sprats
- 1 Bakelite
- 1 Battery 9V
- Cautín
- Drill
- Welding
- Tin

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.

Schematic of an FM radio

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.

Source: Ikkaro

33 thoughts on “Cómo hacer un transmisor de radio FM”

  1. eduardo lainez

    I have almost everything to make a Fm Tramisor! But I only need to count 1 5-60pF adjustable capacitor (trimmer)! and I can't count it!

  2. Hi, can you please tell me the value of the coil? PLEASE!!! and the only solution I see for the variable capacitor is to put an electrolytic one in the range of 5-60pf previously tested with the circuit on the breadboard making sure that the frequency we get is without interference and/or unoccupied.

  3. Elwin Aaron Reyes

    The adjustable capacitor can be exchanged for another one? if a fixed one is possible, how big should it be? because the adjustable one can be found in electronics shops.

  4. Gentlemen, I have a question: if I want my radio to stop working, in other words, to break it down...which component should I manipulate and how? breaking down and disassembling is how I learn...thank you in advance.

    1. in an electronics shop you buy a copper plate and the acid which is ferric chloride....ese is only corrosive when it is with the copper it does not burn but it stains everything you touch.... you print the circuit in L.A.S.S.E.R printer, you iron it on the plate, you put the plate in the acid until it is removed and only the print is left and you are done.

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