Abstract: An improved system and technique for testing power source characteristics simulating dynamic load power demand requirements using pulsating current waves. A plurality of load devices are connected in parallel across the output of a selected power source to be tested. Individual electronic switches are then inserted in series with each of a predetermined number of the loads to allow insertion of the load across the power source at selected times. Using a programmable logic control circuit, the switches are controlled to produce pulsating waves across the power source which simulate the input power demands of actual loads that may be applied to the power source during use. The logic control circuit is constructed to allow programming of plural pulsations per half cycle of an input waveform as well as variable frequency or random frequency control to allow detection of power source deficiencies under a variety of load conditions.