This circuit uses a small microphone to capture the sound & some
transistors to generate radio waves that can be picked up by a FM
receiver like a car stereo.
How it works:
From
left to right, the first part is the microphone & some resistors to
get it working. Next we have a capacitor and the first transistor, this
amplifies the sound from the microphone so that it can be loud enough to
work with. The last part, there is a transistor, a coil and some
capacitors. This part generates the radio waves & combines them with
the sound from the mic to transmit it thru the antenna.
The coil is
made with about 9 turns of wire, use a pencil to get the right diameter
for the coil. The capacitor with the arrow is called a trimmer
capacitor, it has a small screw to adjust the value, we'll use it to
tune a certain frequency or station to transmit on.