What is an IR photodiode?

An IR sensor is basically a device composed of a pair of IR LEDs and a photodiode collectively called optocouplers or optocouplers. The IR LED emits IR radiation, the reception and / or reception intensity, from which the photodiode determines the sensor output.

This sensor module works in accordance with the principle of infrared reflection on the incident surface. A continuous beam of IR rays is emitted by the IR LED. Whenever a reflection surface (white / obstacle) reaches the receiver (photodiode), these beams are reflected and captured. Whenever an absorbent surface (black / unobstructed) reaches the receiver, these beams are absorbed by the surface and therefore can not be captured.

A photodiode is a junction with reverse polarization of silicon or germanium in which the reverse current increases when the junction is exposed to light.

When there is no light on the photodiod j junction, the reverse current is extremely low. This is called DARK CURRENT.

When light enters the junction of the photodiode, there is an energy transfer from the incident light (photons) to the atoms in the junction. This will create more free electrons (and more holes) these additional free electrons will increase the reverse current. This electrical energy can be recorded as voltage drop fluctuations using a serial resistor in the external circuit and reading the voltages on it.


  • Active detection of low objects
  • Easy 3-pin interface connector
  • LED indicator
  • Potentiometer to change the detection range

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