The indicator for this circuit is a 0 to 1 mA milliammeter. The operational is from the 70s, when the circuit was published. Modern equivalent can be used.
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...