FM Transmitter Lovers

Mini FM Transmitter Bug circuit (Use 548)

By SZ123 • 2009-04-12 • Category: FM Transmitter DiyRSS 2.0 Trackback

This small transmitter uses a hartley type oscillator. Normally the capacitor in the tank circuit would connect  at the base of the transistor, but at VHF the base emitter capacitance of the transistor acts as a short circuit, so in effect, it still is. The coil is four turns of 18swg wire wound around a quarter inch former. The aerial tap is about one and a half turns from the supply end. Audio sensitivity is very good when used with an ECM type microphone insert.   From:


Use BC548 X2 Mini FM Transmitter Bug circuit

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