This FM transmitter circuit can be used to supervise a room or for a wireless microphone. To listen the signal can be used any Fm radio receiver.
Construction of this FM transmitter circuit is very simple requiring few components and is very easy to build.
L1 is 0.1uH, 6 to 8 turns of 22-gauge hookup wire close wound around a 1/4-inch diameter non-conductive core . C4 is an trimmer with 4-40pF.
To calibrate this emitter circuit device we must set the radio receiver in the down side of FM scale and rotate C4 until we hear the signal from transmitter device. The maximum distance that the signal can be received is almost 400 m .
The capacitors that are used in this transmitter circuit are ceramic type capacitors .
This transmitter circuit can be powered from a 9 volt battery or a simple 9 volt DC power supply .