Active audio filter (CB21770E)

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

100 MHz Oscillator (CB6187E)
This 80's Motorola circuit can generate 100 MHz signals, but they can reach 200 MHz with the...
Micro High Voltage Generator (CB25720E)
Of course, the current is extremely small, but a voltage of 300 V can be obtained from 9 V of a...
Solid State Relay (CB25258E)
We found this solid-state relay circuit that can function as a shield in a Radio Electronics...