Solid state relay circuit diagram.
A great point of a circuit like this, is the seperation of the DC and AC voltages, so this circuit might be applied in many kind of applications, up to around 1.5 KiloWatt, in case you mount the Triac on a huge cooling-rib.The ‘M’ indicator noted on the Triac means it’s a 600volt design, a ‘D’ stands for 400volt. So be sure you go for the M model.(Tony: The NTE replacements for this circuit are 600volt models which is more than sufficient for our 110/115VAC.) Also, when you make a decision to make a PCB for this circuit, to design sufficient space between the AC lines and do not make these AC tracks far too narrow.