This is one of many configurations of this type that can be found on our website. The circuit uses two inverters and has the frequency determined by capacitor C1.
This circuit uses a resonant reed relay to recognize the frequency of an input signal. Adaptations...
The operational used is uncommon today, but equivalents can be used. Unlike the previous one, this...
This simple circuit uses a zener diode and two LEDs to indicate whether the voltage of a power grid...