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Schematics Depot >> Transmitters >> Miniature FM Transmitter

miniature fm transmitter:
Miniature FM Transmitter
click here to enlarge schematic

Transmitter Parts:
R1, R4, R610K resistor
R21Meg resistor
R3100K resistor
R5100 ohm resistor
R71K resistor
C1, C20.1uf capacitor
C30.01uf capacitor
C44-40pf variable capacitor
C54.7pf capacitor
Q1, Q22N3904 transistor
L18-10 turns of 22gauge wire around non-conductive 1/4" diameter form
Elec MikeElectret Mic
This miniature transmitter is easy to construct and it's transmissions can be picked up on any standard FM receiver. It has a range of up to 1/4 of a mile or more. It is great for room monitoring, baby listening, nature research, etc. L1 is 8 to 10 turns of 22 gauge hookup wire close wound around a non-conductive 1/4 inch diameter form, such as a pencil. C4 is a small, screw-adjustable, trimmer capacitor. Set your FM receiver for a clear, blank space in the lower end of the band. Then, with a non-conductive tool, adjust this capacitor for the clearest reception. A little experimenting and patience may be in order. Most of the parts' values are not critical, so you can try adjusting them to see what happens.
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