This circuit came out in a 60s RCA documentation. The circuit uses common lamps and LDRs but can be implemented with LEDs.
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...