The circuit presented is based on the National Semiconductor's LM3524, a component not common today. The circuit is from the 1994 Linear Applications Handbook.
This circuit was found in Siliconix documentation from the 1980s. Common comparators or...
Found in an 80's Elektor, this circuit can use any equivalent optical coupler. The buzzer is of the...
The idea is simple: using a flashlight to cut your TV commercials triggers a relay that turns off...