Abstract: A control circuit is provided for controlling operation of an electrical or electromechanical system which oscillates at a basic frequency, such as a coil-operated compressor of a vehicle cooling system.The control circuit has a power output stage which feeds operating power to the oscillating system, and a generator which drives the power output stage and is synchronized with the oscillating system.The generator comprises an oscillator which produces a pulse sequence at twice the basic frequency of the oscillating system and a converter which modifies the pulse sequence of the oscillator so that every second pulse fed to the power stage has the same polarity. Feedback from the oscillating system is applied to an input of the oscillator to synchronize the oscillator with the oscillating system.