Geiger counter with high voltage source (CB22333E)

This circuit includes a high voltage inverter to power a Geiger tube. We found it in an American documentation from the 60s.

RIAA Transistor Amplifier (CB19171E)
This circuit, from the 90's, is intended for operation with vinyl record players of the time, as...
Instrument Scale Modifier (CB4159E)
Using a zener diode it is possible to change the linearity of the scale of an analog instrument by...
Chime delay (CB9679E)
Found in American documentation from the 1980s, this circuit prolongs the ringing of a doorbell or chime...