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Voice Transmitter Via FM Band 2 VHF by Hartley Oscillator

Voice Transmitter Via FM Band 2 VHF by Hartley Oscillator

The circuit was designed to operate a frequency modulation voice transmitter over the FM band 2 frequency range of VHF
A Hartley type oscillator was used for the circuit because the frequency may be varied using a variable capacitor, either a tapped coil or two fixed inductors are needed, and the output amplitude remains constant over the frequency range. In a VHF configuration, the base emitter capacitance of the transistor acts as a short circuit as the capacitor in the tank circuit typically connect at the base of the transistor.

Wrapped around a quarter inch rod is a coil of four turns made of 18 standard wire gauge (swg) wire. By wrapping the turns in threads, a uniform separation was made between the coil windings. About one and a half turns from the supply end is the aerial tap or the antenna. Using an electret condenser microphone will provide good audio sensitivity and it can capture any audio in a room


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