We found this circuit in a documentation from the 70s. The circuit uses amplifiers from the time, but it can be implemented with modern equivalents.
When this circuit is activated the LED flashes for a moment indicating that the function has been...
This 1970 Electronic Design circuit uses a varactor or varicap. The circuit divides the frequency...
Found in a 1993 Electronics Hobbyst Handbook, this passive circuit can be used with common...