Found in a 1992 book, this circuit is intended for operation with audio signals. Equivalent operational amplifiers can be used. The optical coupler is an unusual type today.
This circuit appears on the site in several variations depending on the source. This is from a...
This counter performs the same function as the 4020, but includes an internal oscillator. The...
Found in a 1968 Electronics World, this circuit uses operational amplifiers from that time. |...