This circuit was found in a RE Experimenter Handbook from the 90's. The components are of the time, rare nowadays, except the 555 and 4017.
This 1992 circuit operates in the range of cordless phones used at the time. The circuit is based...
Indicated for frequency measurements, this circuit can operate with inputs up to 1 MHz. We found...
This circuit was originally developed in 1989 to allow the triggering of loads from audio signals...