This 80's circuit uses a germanium transistor like the AC121. The circuit has an output transformer of the type found on many transistor radios of the time.
This simple electroscope with bipolar transistors is not the most sensitive, but can detect static...
This circuit is suggested by Texas Instruments in his Optoelectronics Sourcebook. Any photo...
The frequency generated by this circuit depends on the crystal used. Frequencies up to a few tens...