This circuit was found in General Electric documentation from 1964. It makes use of a PUT, called the PNPN planar key at the time. The circuit has two supply voltages.
This double tone generator uses a specific integrated circuit, having been found in a 1977 CMOS...
This circuit is used to test PNP or NPN transistors giving the status indication through LEDs. The...
This dimmer for incandescent lamps was obtained from an American 1990s documentation. The circuit...