The figure shows a typical circuit of a variac with a special transformer with sliding adjustment of the winding turns. The circuit is from an Electronics Now magazine from December 1997.
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...