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.
This circuit was obtained in a 1991 Electronics Handbook. The publication no longer exists, but...
This simple 1 transistor radio was found in Raytheon's transistor manual. The transistor is...
This power supply was described in an article in Radio Electronics magazine from July 1968. The...