This circuit converts a high voltage into a frequency using an optical coupler. The transistor can be 2N2646 and the coupler admits equivalent. The circuit is from a 1974 publication.
Found in an Electronic Design from the 80s, this circuit uses an unusual component today, the...
The CMOS TLC555 can be gated from external CMOS circuits using the configuration shown here. The...
This circuit was obtained in a Motorola manual from 1978. We can use any triac and the coupler with...