Just to add that the very first batch of Analyser Pro/StopClock Professional did use triacs but we reverted to electromechanical relays as some enlargers didn't like the triacs very much - specifically the LPL 5x4 which has its own relay. The leakage current through the triacs was sufficient to keep the LPL's relay closed when switched off - obviously it was a very sensitive relay! If you can hear a "click" when the timer switches the enlarger on or off, then it's NOT a triac model.