Abstract: A voltage surge suppression circuit for a low voltage coaxial cable comprises a gas tube connected across the signal and shield conductors and an MOV connecting the shield conductor to a ground. In the case of a balance signal line comprising two conductors, a first gas tube connects one line to ground and a second gas tube is connected across both conductors. A third gas tube may connect the other conductor to ground in which case the second gas tube may be optional. The ground is preferably a ground associated with a power line voltage surge suppression means.

Abstract: A programmable system controller is disclosed which is particularly suited for monitoring a correctly responding to user commands initiated by telephone and switch activations. The switch activations may be generated by switches of the two or three wire maintained type or momentary switches. The switch inputs are routed to a switch conditioning circuit that compensate for such problems as switch bouncing or noise levels associated with the switches. The telephone commands, in the form of an electrical signals, are routed directly to the programmable device of the system controller. The programmable system controller comprises the programmable device which responds to the switch conditioning circuit to determine the particular type of switch generating the switch command and the validity of the switch command. The programmable device in response of the valid commands and telephone commands provides a digital quantity to a sequencer, which, in turn, activates output devices such as one or more banks of relays.

Abstract: A voltage surge suppression circuit employs two series connected metal oxide varistors and a power interrupter to provide suppression of all modes of voltage surge while providing protection against failure of either metal oxide varistor. An indicator is provided to indicate the status of the circuit to the user.

Abstract: A control circuit provides full range power control to a pair of electrical loads via a single two-wire power cable by controlled switching of a bidirectional solid state switch during each consecutive half-wave cycle to supply power to one load during each positive half-wave cycle and to the other load during each negative half-wave cycle. The switching during each half-wave cycle is controlled by a respective trigger circuit. Interference by power supplied to one load with the operation of the other load is prevented by removing any residual voltage from the respective trigger circuit at the end of each half-wave cycle.