Preamp for Speaker as a Microphone

Preamp for Speaker as a Microphone
This Microphone Preamp circuit shows that it is possible to use the speaker as a microphone, and is specifically designed to beginners because of its simplicity. Power consumption, of about 2mA, allowing the circuit is operated a few hours on a single 9V battery. However, it does not prevent you to use a stable power supply, or solar cells ... (more…)