This is a circuit of crystal radio transmitter. I've tested it, and it works properly. but I can't understand everything in this circuit…
L1 and C5 make resonance frequency, Would you tell me if they are series or parallel and why ?
C1 , R1 and C2 for filtering the Audio (input). Am I right ?
What is the function of C4 ?
Best Answer
Actually, L1 and C4 are the resonant tank circuit for the oscillator. They are in parallel, because C3 effectively shorts the RF signal to ground. C5 provides the feedback to the transistor so that it oscillates.