Simple FM Transmitter

[Electron]

Those of you with a basic working knowledge of electronics and some soldering skill should be able to make this. It is available at various places on the Internet. It transmits a Frequency Modulated (FM) voice signal. The frequency is adjustable. With the coil at 8 turns, the frequency range is 88-110 MHz (use with a common FM receiver). You can add more coils for a lower frequency, or have fewer coils for a higher frequency. It's uses are limited by your imagination. It is FCC compliant as the circuit is now. Slight modificatiions to some components and the antenna will give you more power. As the circuit is now, you should be able to get about 100 meters range from it. It is simple enough that you should be able to construct it using experimenter's perf-board and point-to-point soldering, so an etched and drilled circuit board isn't necessary. C6 in the text can be replaced with a low picofarad capacitor, anywhere from 2 to 5 pF will do.

[Razor]

Electron, what did you use to "weatherproof" the transmitter on the right?

[Electron]

you can use almost anything. In the pic, I used hot glue. Be careful because the glue is unforgiving, so is paraffin wax. Don't glue/wax over the microphone sound hole or the battery contacts. I would recommend simply wrapping it tightly in cling wrap and a piece of tape to hold it in place, that way your battery is protected too.