Abstract: A control service delivers controlled magnitude energy from a sinusoidal power source in the form of a sequence of pulses conforming to the sinusoidal envelope. A gate signal operated at a selected frequency applies gating pulses to a gating device receiving the sinusoidal power signal and applying its output to a load. The load receives, at high gate signal frequencies, substantially all energy presented in the power signal and, at lower gate signal frequencies, a selected magnitude energy taken from the sinusoidal power signal. The power applied to the load does not produce undesirable noise or radio frequency interference and does not require use of an expensive, heavy and volumous choke or inductor.

Abstract: A solid state relay includes a protective input stage at its control terminals to isolate the control circuit from line voltage or line current in the event of relay failure. The protective circuit includes a series combination of a voltage responsive element and a current responsive element. The current responsive element connects to the input or control terminal of the solid state relay and the voltage responsive element connects to ground. The interconnection of the current responsive element and voltage responsive element serves as the device input terminal for connection to a control circuit. In the event of relay failure, the voltage responsive element reacts to the increased voltage by providing conductivity, by way of the current responsive element, between the solid state relay input terminal and ground.