This circuit is from a 1975 Miniwatts magazine, therefore using Philips components from that time, now difficult to find. The circuit directly controls a heating element via a Triac.
In this circuit the photo-transistor signal is amplified by a Darlington step and then applied to a...
The purpose of this circuit of an American publication from the 70s is to move the signal from an...
This 80's circuit can be implemented with modern equivalent FETs with lower on resistance. The...