D.C. SWITCH CIRCUIT

A circuit for a switch which receives an input from a sensor head (18) such as a proximity sensor, limit switch, or other type of condition-responsive sensor. In its most complex form the circuit includes a power supply/ regulator (24), an output load current source (12), an output load current sink (14), input logic (16) to receive the signal from the sensing head, a selector (10) to determine whether the source and sink will be normally open or normally closed, and means (26) for checking the ouputs for faults and indicating the presence of such. Other circuits include certain combinations of these parts or variations of these parts.