This circuit was obtained in an Electronic Engineering of the 90s. The operational amplifiers and the sensor are from that time. The circuit has symmetrical power supply.
This light control for triac incandescent lamps can be seen elsewhere on this site. This version is...
Although it is not convenient to directly associate triacs in parallel without a resistor that...
This transistorized “grid dip” oscillator was found at Radio Electronics in June 1953. The...