Patent US 3,958,126

A burner control system has a field device and control logic for providing a control signal to change the state of the field device. A comparator that compares signals from field and the control logic comprises translation circuitry that is arranged to produce an output pulse train signal in response to a corresponding input pulse train signal, and power supply circuitry that has two logic inputs. The power supply circuitry supplies power to the translation circuitry only in response to a proper comparison between a field signal applied to one logic input and the control signal applied to the other logic input.