Found in a 1960s RCA documentation, this circuit applies to most common triacs. The trigger device is a neon lamp and the sensor is an LDR. R is typically 100k and C is 220 nF.
We found this circuit in an American 80's documentation. The circuit can be adapted to function as a...
This 80's circuit, suggested in Texas Insrtruments documentation, uses a Hall effect sensor. The...
This interesting benchtop circuit was found in the May 1977 issue of Radio Electronics magazine. The...