Abstract: The power supply, useful with an electromagnetic force apparatus such as a riveter or a bolt inserter, includes two capacitor banks which are charged through charging doubler modules. Each charging doubler module includes an AC capacitor which is responsive to a power source. The AC capacitor is connected to a node point between two diode elements, which are connected in series across the capacitor bank. An analog-to-digital converter converts the voltage on the capacitor bank to a digital voltage for comparison with a selected digital charge voltage in a controller. The selected digital charge voltage may vary over time by means of a compensating algorithm. A ground fault indicator using a biasing voltage is connected between a selected electrical circuit portion of the force apparatus and earth ground. A gas discharge tube in combination with a current sensing element is connected to the capacitor banks to determine a possible overvoltage condition.