Wireless Microphone


Wireless Microphone circuit

Parts List: R1 = 10K (brown-black-orange)R2,R3 = 100K (brown-black-yellow) R4 = 470 ohm (yellow-violet-brown)C1,C3 = 4.7pF (4p7), ceramicC2,C4 = 4.7uF-16V, electrolytic C5 = 0.001uF (1nF), ceramic C6 = 470pF, ceramicQ1,Q2 = 2N2222, NPN transistor L1 = 1uH, variable inductorMic = Electret mike, 2 wires

Couple Notes:
Q1 amplifies the input signal via C4 from the electret microphone.
Q2 acts as an oscillator and the signal coming off C2 is fed onto the base of Q2.
L1/C1 is a so called ’tank’ circuit and operates in the 88-105MHz band on your regular AM/FM radio dial.
L1 is a 1uH variable inductor coil to be able to tune it a little bit, and the range of 1uH is approximate.
The antenna can be as simple as a 8″ (21cm) piece of wire of any kind.


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