The input and output frequencies of this circuit depend on the coils and capacitors of the tuned circuits. The circuit is from Electronics Now magazine, February 1997.
This circuit was obtained from a Hands On-Electronics, an American magazine from January 1987. This...
Using the CA3140 in the figure we have a comparator that goes low in the window voltage space. The...
This circuit is from a Popular Electronics from the 90's. The circuit activates a buzzer with...