Infrared-based sensing circuit providing an output simulating the output of a flame rod sensor

摘要

A converter circuit (11) provides an output signal of polarity opposite that of an input signal having a DC component and a low frequency periodic component in response to presence of that input signal. Current is transferred from a first capacitor (32) to a second capacitor (50) to accomplish this conversion. The circuit has particular application in a flame sensing interface circuit using a sensor of the infrared radiation generated by the flame to change the impedance of the sensor. By use of the circuit, the output of an infrared sensing amplifier imitates the output of a conventional flame rod sensor, and provides an output signal compatible with the output of a flame rod to the input to a flame signal processor.