The circuit shown is from the 1994 Linear Applications Handbook by National Semiconductor. Some of the components are not currently common and should be looked for equivalents.
This 6V microsupply with just 2mA current uses a common 1N34 germanium diode. The circuit was...
This circuit triggers a buzzer or other warning device when the light falling on the sensor is cut...
This circuit was originally designed to automatically turn on a television when a video game is...