Dynamic compressor (CB21762E)

This circuit was found in a 1977 publication for radio amateurs. Transistors are common general-purpose types of the time.

Regulator 0 to 40 V x 500 mA (CB14520E)
The integrated circuit used in this project is uncommon and so are the transistors, but they can...
Light Relay with SCR (CB14636E)
We found this circuit in an old optoelectronics manual from Texas Instruments. However, more...
Wavemeter (CB4118E)
It actually consists of a tunable field strength meter. The circuit is of an old documentation and the...