Simple FM transmitter

Simple FM transmitter circuit made with few easily available components, This Frequency Modulation reaches several meters to kilo meter with low power transmitter circuit. Here two transistor based FM circuit diagram given for hobby use. The condenser mic converts voice signal into audio signal and transistor Q2 amplifies the audio (message) signal. The Q1 transistor is produces Carrier frequency.




Amplified audio(message) from Q2 transistor is directly applied to the Q1 transistor base terminal. Hence frequency of carrier signal varies according to the audio (message) signal. By the way we get FM wave from the collector terminal of Q1 transistor. By using lengthy monopole antenna we can transmit FM wave up to several kilometres.

Simple FM transmitter

(always tune the FM Carrier frequency in the transmitter to a license free band)

Components List

S.No Name Quantity
1. Transistor 2N3904 2
2. Condenser MIC 1
3. Gang capacitor (variable capacitor) 4 to 40pF 1
4. Capacitor 1 &uF (disc type) 2
5. Capacitor 0.01uF
Capacitor 4.7pF
1
1
6. Resistor 10KΩ
Resistor 22KΩ
Resistor 100KΩ
Resistor 100Ω
Resistor 1KΩ
3
1
1
1
1
7. Inductor 0.1uH 1




10 thoughts on “Simple FM transmitter

    1. Thank you for your interest 🙂 Van baug!
      First thing you have to identify the carrier frequency range.
      Second thing you have to tune your receiver to that particular carrier frequency range.
      here the circuit is given for free fm bandwidth utilization, Use free band fm frequency specified in your country.
      hope you got answer.

    2. Tune the Transmitter Frequency in between to the Receiver min and max Frequency Range. It is advised to make a FM Receiver that is capable of demodulating Transmitter Frequency.

  1. hi there,can you please tell me how to make the inductor,i.e all the details about the guage of the wire used and also number of turnings made

  2. Am Andy Bakers From Uganda ,Thanks For Your Help, Can Is Use A Digital Microphone To Transmit My Audio Music To Fm Receivers/radios? Thanks

  3. I don’t have a 4.7 of cap, I thought about combining ones I have but it would take dozens or so of my smallest one , .00047 ùf , I only.had two! Oh well. I need hit radio shack , if they even have something that small and precise, any diy ideals ? Maybe a transistor radio laying around?

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