Simple and easy build of sensitive FM transmitter circuit. The circuit only requires 2 transistors to work.
*L1 = 0.1 Uh, 6 to 8 turns of 22 ga. hookup wire close wound around a 1/4 inch diameter non-conductive core such as a pencil
Typically the default for the capacitors model is ceramic, preferably the npo 1% type or equivalent. However, generally almost nothing critical right here. Work with any capacitor you’ve laying arround, but DO NOT use any electrolytic or tantalum capacitors. Only in case you intend to apply this circuit outside the home you may need to use capacitores which have more temperature stability.
To find the signal on your receiver, make sure that there is a signal coming into the microphone, otherwise the circuit won’t work. I use an old mechanical alarm clock (you know, with those two large bells on it). I put this clock by the microphone which picks up the loud tick-tock. I’m sure you get the idea… You can play your phone music and place near the microphone, or you can just lightly tap the microphone while searching for the location of the signal on your receiver.