Abstract: A phase-lock system including an oscillator providing a switching output that continuously switches between first and second states, a trigger circuit for inducing switching of the oscillator, a sensing circuit monitoring the switching output and providing an anticipating indication of an imminent switching thereof from the first to the second state, and a primary voltage source providing a variable voltage that periodically varies from and returns to a given voltage level. Also included is a detector circuit monitoring the variable voltage and detecting the presence of the given voltage level and a synchronizing circuit responsive to the sensing and detector circuits and providing an input to the trigger circuit, the synchronizing circuit being operative to cause switching of the oscillator in response to the simultaneous provision of the anticipating indication by the sensing circuit and detection of the given level by the detector circuit.