Silent alarm (CB22471E)

This circuit is from a Popular Electronics from 1992. The circuit powers an LED when triggered.

Intermittent buzzer (CB20494E)
This two-tone buzzer can be powered by a solar panel. The circuit is from a 1991 documentation. The...
Audio Oscillator (CB22250E)
This blocking oscillator was found in a publication from the 50's. The coils determine the...
20W amplifier per channel with the TPA3100D2 (Cb23591E)
The TPA3100D2 integrated circuit from Texas Instruments (www.ti.com) consists of an efficient...