Abstract: A drive circuit for a photoelectric sensor which automatically adjusts the sensor response time with adjustments in the drive current to the light source based on a desired sensing distance. The drive circuit includes an oscillator for establishing an output signal having an output frequency. An output of the oscillator is provided as an input to an adjustable current source. The current source is connected to the light source for providing the drive current to the light source at the output frequency. A peak detector is connected to a lead of the light source for detecting a feedback voltage proportional to the drive current through the light source. The feedback voltage is provided as an input to the oscillator, and the output frequency of the oscillator is variable depending on the feedback voltage so that variations in the drive current result in corresponding variations in the output frequency and, therefore, the frequency of the drive current.