The circuit is from the 1990 Motorola Linear Databook. The circuit can be implemented with other operational amplifiers. The power supply must be symmetrical.
This circuit was found in old American documentation. Transistor is general purpose and relay is...
This simple alarm with latching uses a relay as the main element. The circuit is from a Radio...
This circuit is from an Italian publication called Fare Elettronica from 1987. What we have is an...