This power step drains just 3.5 mA from the battery and can provide good playback on a 4-ohm speaker. The circuit is from an 80's documentation.
The circuit illustrated in Figure allows external loads (8) to be driven from parallel port...
This circuit uses two transistors to simulate the action of an SCR on a regenerative switch....
The filter presented is from 1994 but can be implemented with a more modern equivalent. We found...