We found this circuit in an old American documentation. The operational amplifier is from the time and the output used to control an SCR or other power control.
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...