How exactly does an Fm transmitter work?

Question

Hi! How exactly does an FM transmitte r work? What does every single component do in the process? Please explane in detale.. Thanks for eny answer!

michaelwylie · Accepted Answer

I'm not sure how much you know, but the basic circuit you have shown is an oscillator where the oscillator frequency can be slightly modified by the microphone. The values of L and that 36 pF capacitor are creating a tank circuit which defines the carrier frequency. Do you need more than this?

dougw · Answer

Hi Magnus, FM (frequency modulation) simply means the transmitter output frequency is proportional to the amplitude of the input (modulating) signal. The larger or louder the input signal the higher the transmitter frequency. The amplitude of the transmitted signal is constant - only its frequency changes. There is a large amount of information on the internet about FM if you need real detail: What is FM | Frequency Modulation Tutorial | Radio-Electronics.com

michaelwylie · Answer

There are three basic ways to modulate information onto a signal. Look at the basic equation for a sine wave:

A(f,t) = Amplitude * sin(2*pi*frequency + phase)

You can either change the amplitude, frequency, phase, or any combination there of. If you change the frequency in proportion to your signal of interest, then it's called frequency modulation.

Edit: There are many FM modulation circuits. If you would like to post one, I'm sure we could decipher it for you.

How exactly does an Fm transmitter work?

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