Stereo preamplifier (CB8510E)

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

3-transistor amplifier (CB23537E)
This transformerless 16-ohm speaker circuit was found in a Radio Electronics from October 1963. The...
Solar power source (CB20481E)
In the figure we have a solar power source for experiments with this type of energy. The cells must...
Digital Capacitor Meter (CB17506E)
This circuit was found in a 1986 documentation and it may be difficult to obtain some of its...