A digital technique is described for controlling the application and removal of base drive to parallel connected power transistors so that they switch on and off in synchronism, and with minimum power dissiptation. The control circuitry was designed specifically for integration on an uncommitted logic array to produce a dedicated integrated circuit. This circuit, together with its power transistor, associated base drive and emitter current sensing circuitry forms a power module which can be operated in parallel with other similar modules to form a switch mode power regulator of any required current rating.