Active audio filter (CB21770E)

This circuit was found in a 1977 documentation for radio amateurs. Integrated circuits are common operational amplifiers.

High Speed Single Pulse (CB6351E)
This high-speed circuit was found in 1980s Linear Technology documentation. The circuit makes use...
TwoTransistor Amplifier (CB987E)
The transistors of this amplifier for 8-200 headphones may be the BC548 or equivalent to replace...
Pulser with relay (CB23666E)
The frequency of this pulser depends on the capacitor and the characteristics of the relay. The...