Crystal variable oscillator (CB9506E)

Found in Radio Electronics from the 90s, this circuit can vary the frequency in small values around the crystal frequency.

1W Amplifier (CB6293E)
The PA222 integrated circuit used in this project from an American 1967 documentation is not...
Infrared Alarm (CB16907E)
This circuit with an optical path sensor was found in a 1995 documentation. The circuit fires...
50 ohm line booster (CB6221E)
This circuit was found in an 80's Electronic Design. It amplifies TTL fast signals for a coaxial...