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FM Stereo Transmiter
You'll find that this is a very easy project to build. It will transmit good quality
sound in the FM band ( 88 - 108 mhz ). One inportant item is that the IC chip operates on
3 volts DC. The chip will get destroyed if it is operated on any voltage higher than 3.5
volts. The antenna can be a standard telescopic antenna or a 2 foot length of wire. The
input is in the millivolt range and you may need to add additional pots for the inputs. I
was able to use this circuit for a walkman and a portable CD player in my car. I used the
headphone jack on both and varied the signal with the volume control.
To adjust the circuit tune your FM radio to a quite spot then adjust the trimmer
capacitor C8 until you hear the signal that you are transmiting. When you have a strong
signal adjust the resistor R4 until the stereo signal indicator lights. If the input is to
high of a signal you may over drive the IC chip. Use two 15 turn pots on the input signals
to bring the level down. You can balance the signal by using headphones. The inductor L1
is 3 turns of .5 mm wire on a 5 mm ferrite core.
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