Stereo preamplifier (CB8510E)

Found in a 90s Popular Electronics, this circuit is based on a uA739, an unusual component today.

Electroscope (CB4341E)
This simple electroscope with bipolar transistors is not the most sensitive, but can detect static...
Multi Frequency Oscillator (CB4226E)
This oscillator for various frequencies was obtained from a 1980s telecom documentation. The...
Water-Activated Triac Switch (CB24054E)
This circuit is from a July 1970 Radio Electronics magazine. The sensors are metal probes. The 18 V...