This shield with full-wave triggering was found in the Radio Electronics Experimenter magazine of 1989. The Triac must be according to the load that must be controlled.
In the figure we have a bistable multivibrator using an operational one. The circuit is from old...
This is another of the Star Trek red alert circuit that you can find on this site. We took this...
This circuit for testing zener diodes by lifting their curve on an oscilloscope was presented in...