This circuit is from an1966 General Electric documentation. The Triac can be equivalent to 6 A or more, mounted on a good heatsink. Any diac can be used.
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...