Abstract: Switch card apparatus are disclosed. In one embodiment, a circuit includes a first portion having a first switch adapted to be coupled to a first voltage, a second portion including a second switch, and a third portion including a third switch. The first portion activates the first switch to couple the first voltage to the second portion. Similarly, the second portion activates the second switch in response to a second input signal and the first voltage to couple a second voltage to the third portion. Finally, the third portion activates the third switch in response to a third input signal and in response to the second voltage from the second portion to couple a control voltage to a load. Embodiments of the invention provide the desired reliability suitable for a variety of electrical systems, including arming and firing applications over a wide voltage and wide current range.