We found this circuit in a 90s Popular Electronics. The circuit can be implemented with modern components. The power MOSFET is according to the controlled load.
The idea is simple: using a flashlight to cut your TV commercials triggers a relay that turns off...
Found in documentation from the 70s, this circuit uses an operational one from that time. It goes for...
Found in a Popular Electronics from the 90s, this circuit uses thermistors for low noise...