This circuit was found in documentation from the 90s. The operational amplifier is NE5514, which is uncommon today. The configuration can be adapted to use modern components.
This control panel allows the use of NO and NC sensors, turning the alarm on after 30 seconds...
This circuit, found in a 1989 publication, only works with incandescent lamps. The maximum power...
We found this circuit in a 1968 Electronics World. The potentiometer should be set to trigger the SCR...