Hello! First of all, I'm new here, nice to meet you all. I have been trying to follow and build this circuit: http://www.cie-wc.edu/fmtransmitter.asp Then I noticed that if I wanted to use a 3.5" jack instead of a microphone, I would need to change something else in the circuit. What would be changed in order to use an audio jack instead of a electret microphone to transmit? Also, I couldn't find a 5-30pf variable capacitor, but I have these two: One like this: http://www.kpsec.freeuk.com/photos/rapid/capvar.jpg taken from an old radio. It has 7 pins, four small knobs on one side, and a bigger one on the other side. It does not have any model number. And another one, a small two-pin trimmer that goes up to 70 pf. Could one of those be used for the circuit, or should I try to get the correct one? One more thing, I hope it doesn't bother you: Where in the circuit could I add a white LED so I know the battery isn't dead? I think it's 3V, but maybe it's more, since it doesn't look very bright on a cell battery. Thanks in advance.