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.

Audible Ohmmeter (CB21603E)
This circuit uses a PUT, a component not very common nowadays. Its purpose is to provide an...
555 in Cascade with Automatic Retrigger (CB1265E)
We found this configuration in a documentation for radio amateurs from 1974. The circuit can be...
Integrator 741 (CB12990E)
In the figure we have the simple way to obtain an integrator with an operational amplifier of type...