The largest Electronic Circuits Database on the Net

                              

FM Transmitter Circuits

  Page 3

In a frequency modulation (FM) transmitter, it is added by varying the radio signal's frequency slightly. Many other types of modulation are used.

In an FM (frequency modulation) transmitter the frequency of the carrier is varied by the audio signal. Angle modulation is the proper term for modulation by changing the instantaneous frequency or phase of the carrier signal. FM transmitters can be stereo as well and using a PLL tunning circuit you can achive a stable audio transmition on FM band.
 
True FM and phase modulation are the most commonly employed forms of analogue angle modulation. Direct FM (true Frequency modulation) is where the frequency of an oscillator is altered to impose the modulation upon the carrier wave. This can be done by using a voltage-controlled capacitor (Varicap diode) in a crystal-controlled oscillator or frequency synthesiser.
The frequency of the oscillator is then multiplied up using a frequency multiplier stage, or is translated upwards using a mixing stage, to the output frequency of the transmitter.
 
 In some indirect FM solid state circuits, an RF drive is applied to the base of a transistor. The tank circuit (LC), connected to the collector via a capacitor, contains a pair of varicap diodes. As the voltage applied to the varicaps is changed, the phase shift of the output will change.
 

Circuits




When I was 8, I came across Art Swan's FM transmitter circuit. At the time I had no idea of where I'm supposed to buy the parts, so I recycled mine out of junk. I guess the biggest struggle that yo...

The FM transmitter circuit itself is based off one of [Art Swan]'s builds, but instead of the solderless breadboard construction you would expect to find in a small demo circuit, [Angelo] went all ...

This is a simple wireless FM transmitter circuit which uses RF communication to transmit the medium or low power FM signal. Its maximum range is 2 km.

Hello every body I'm glad to register in this forum it is one of the good forums that I've seen. Dears I have a project which is about creating a Fm...

If you use too many jumpers, that may induce unwanted inductance and capacitance in the circuit and that will shift the transmission frequency of the transmitter. This applies not only to this FM t...

Here's a small FM transmitter ciruit for your desktop or laptop to enjoy the movie and music from a distance. This FM transmitter, which is powered by USB, recovers output on your computer or your ...


Weekend Projects - Super Simple FM Transmitter


A Breadboard FM Transmitter Bug


About Radio part 41 Quality Audio FM Transmitter


How to build a SPY Bug