This is one of the many versions of this oscillator that we have on our website. We found it in an article in Radio Electronics magazine from January 1987. The frequency depends on C1.
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...