Dynamic compressor (CB21762E)

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

Airflow detector (CB7427E)
Found in a Popular Electronics from the 1990s, this circuit uses components from National...
Combination switch (CB22209E)
This combination key or code key was found in old documentation. The consumption is very low, and...
Nicad Protected Charger (CB6401E)
This circuit was found in a European documentation from 1964. The circuit makes use of components of...