Above schematic diagram is a small 325mW amplifier circuit based on LM386 with a voltage gain of 200 that can be used as a simple bench amplifier, signal tracer or used to amplify the output from personal radios, MP3 players, MP4 Players or iPods.
Here the simple schematic of multitone siren alarm circuit. This multitone siren is effective for reverse horns, burlgar alarms, and many others. It generates five various audio tones and is much more earcatching than a single-tone siren.