#31 One Transistor FM Transmitter Using Colpitts Oscillator

One common transistor and a few parts make an oscillator that can transmit to an FM radio, for example. Try this for yourself and please let me know how easy/difficult it was to get it to oscillate.
If you should try it, first get it going without the modulator portion.

Note that I used a basic FM radio that tunes continuously across the band. If you use a digitally tuned radio to receive, it may only tune in 200kHz steps and your transmitter might be in between one of those steps and you'll miss it. You can insert something like a screwdriver shaft or a nail in to the coil to move it's resonant frequency.

For the two tiny capacitors in the tank circuit try values between 20 and 100pF. And for the tank circuit inductor, try 35 or so wraps of small solid core wire around a form (AA battery is a nice size) and secure it with some tape before sliding it off the form.

Correction: 9.2 MHz not "9.2 kHz" at 5:40



0:00 Intro To Colpitts Oscillator
0:54 Oscilloscope Waveform
1:45 Voltage Controlled Frequency
2:43 Harmonics On Spectrum Analyzer
4:23 Schematic Discussion
5:50 Crystal Instead Of Inductor
6:30 Common Components Used
6:56 Modulator
9:00 Breadboards And Radio Frequencies