This circuit was found in an Electronics Now from the 90's. The integrated regulator circuit and the power transistor must be equipped with heat radiators.
This light-activated switch triggers a 6 V relay. The circuit can operate with 12 V and relays for...
The XR2206 is not a common component today, but if you have one you can build this function...
This circuit is from the 1990 Motorola Data Databook. The circuit can be implemented with...