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.
The circuit in the figure is from a source with the possibility to adjust the output voltage from...
We found this circuit in a 1965 General Electric manual. The circuit applies to incandescent lamps only and...
We found this circuit in an American publication from 1977. The circuit drives two LEDs according to...