Learn how to interface electret and dynamic microphones to the standard computer sound card.
Theory of operation and schematics of the most common metal detectors used today: Very Low Frequency (VLF), Pulse Induction (PI) and Beat-Frequency Oscillator (BFO).
The wireless microphone transmitter can be built in an afternoon with simple, affordable and widely available parts. Take care with transmitter circuits. It is illegal in most countries to operate radio transmitters without a license. But the output power of this circuit is below the legal limits of many countries (e.g., USA and Australia).
Audio Power amplifiers:
High efficiency Class D amplifiers: 10W with TDA7480 and 170W with LM4652.
Various power audio amplifier ICs:
20W Audio power amplifier with TDA2005.
Power amp. schematics with LM386.
4W audio power amplifiers with TDA1013b.
10W Audio power amplifiers with TDA2003
Audio power amplifier schematics with TDA2040