2-TRANSISTOR FM TRANSMITTER by 2N3904,2N2222

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While there are a plethora of similar 2-transistor schematics available, this one is above average. A major improvement over the little 1-transistor circuit that we’ve discussed previously, this transmitter consist of two stages. The first transistor is used to amplify audio, which means that the microphone is now much more sensitive to sound. The second one acts as an oscillator.

All in all, this is an interesting project for beginners and more experienced hobbyists alike. Use any stiff wire or telescope whip antenna, just make sure that it’s not too long. Range should be about 100m or even more in the open. Stability is still a problem, though.

Part
R1 270
R2, R5, R6 4k7
R3 10k
R4 100k
C1 1n
C2 5.6p
C3, C4 10u
C5 3-18p
L1, L2 5 turns of enamel coated magnet wire with an inside diameter of about 4mm
Mic Electret microphone
Q1, Q2 2N2222, 2N3904 or any other general-purpose NPN

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This entry was posted on Monday, January 21st, 2008 at 11:56 am and is filed under RF-Radio Frequency, fm transmitter. You can follow any responses to this entry through the RSS 2.0 feed.