The circuit is from 1968, but we can use a modern one like the 741. The symmetrical power supply voltage (two batteries or source) can be from 9 to 12 V.
This circuit was obtained in a 1967’s EEE. Transistors and integrated circuits can be replaced by...
This source, found in a 1991 publication, was originally designed to operate with the CB18736E, an alarm...
This circuit is from Motorola's 1990 Linear Databook. We can implement it with other operational...