This circuit shows that we can implement a voltage-controlled oscillator with almost any CMOS that can be connected as an inverter. The circuit is from Radio Electronics from January 1987.
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...