Schematics Depot >> Transmitters >> 4-Transistor Tracking Transmitter
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The author of this schematic actually has a site with cool pictures and a description of this schematic. You can see Tony's page here: http://www.uoguelph.ca/~antoon/circ/tx15trak.htm
Comment from Randal Miller (5/4/2006)
The circuit is a common form used in FM transmitters. The transistor conducts for 60-90 electrical degrees. When it turns off the LC tank 'rings', completing the sinusoidal waveform coupled to the antenna. The circuit is 77-85% effecient, compared to 40-50% for a linear oscillator.