We found this circuit in an article that describes several alarms that are in the sequence in our section. The article is from the Radio Electronics magazine of May 1971.
Frequencies up to just over 100 kHz can be obtained with an oscillator based on one of the four...
This circuit, found in a Popular Electronics from 1992, is based on an oscillator and a crystal...
This is a discrete equivalent version of an open collector TTL gate. What we have is an inverter...