This circuit was found in an American 1990s documentation. It can directly trigger a triac when light is detected by the sensor. The integrated circuit is common, like the 741.
Found in the July 1968 Supertena Bulletin of a Popular Electronics, this receiver makes use of the...
This switching source was obtained in a 1976 National Semiconductor manual. For the indicated...
This configuration appears several times on this site. The circuit can generate a 100 kHz or other...