This circuit was found in the April 1971 Radio Electronics magazine. It uses common transistors and can be adapted to use an LED or audible indicator instead of a light bulb.
We found this junction tester circuit in an old English documentation. The circuit serves to check...
This circuit can generate signals up to 100 kHz. Found in documentation from the 1980s, it makes...
Found in American documentation from the 70s, this circuit uses components of the time, uncommon...