This 1969 circuit uses a 117 V filament tube powered directly by the power grid. The original circuit makes use of a charcoal microphone, a common component at the time.
This circuit, found in a 1994 documentation, uses 20 A 2N5448 triacs or equivalent and should be...
This conventional power supply circuit with the LM317 was found in a 1987 publication and its...
This automotive circuit was obtained from an 80's schematic from the integrated circuit factory...