I Recently disassembled two printers, and I found a lot of neat sensors that I'd like to use for my projects. I've tried to search around the web, but I can't seem to find any pin out or datasheet for this type of sensors. They are kinda similar to the photo interrupters, but these seems to have 6 terminals instead of four. Here's some pictures:

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Also I may add that some of them come with five wires, but most of them have just four.

Hopefully someone here could help me out, a circuit diagram of some sort would be really helpful as well.



I've powered the sensor as recommended, and I found that pin 3 is connected to the "photo interrupter"-part of the sensor. I measured about Vcc between pin 3 and GND when the IR-light was blocked, and about 0V otherwise.

I didn't find any variations for pin 2, it stays at Vcc. Any ideas? But I have yet to try the "motor-sensor".


simulate this circuit – Schematic created using CircuitLab


2 Answers 2


At a guess, that's a very specialized 2-channel reflective optical sensor, which is optimized for use as a quadrature encoder. I do hope you kept the motor and wheel.

Looking at your middle picture, it's likely that the lower pin, with its associated large trace, is ground. The two middle pins are obviously the sensor outputs, which leaves the top pin as the power. I'd suggest you try 5 volts.

Assuming I'm right, the optical spacing of the two channels is very specific to the line spacing on the code wheel, so you're unlikely to get much use out of the board, except perhaps as a simple proximity detector.

  • \$\begingroup\$ Alright, thanks. I will try to connect the sensor as you described, hopefully I will get some results. And yes, I did keep the motor and the wheel. \$\endgroup\$ Aug 23, 2016 at 12:56
  • \$\begingroup\$ "The two middle pins are obviously the sensor outputs", so if there are two outputs, do you have any idea what they would measure? \$\endgroup\$ Aug 23, 2016 at 12:59
  • \$\begingroup\$ Sure. They measure the position of the opaque/clear portions of the wheel. The two channels, for a rotating wheel, should be in quadrature - that is, they should be two square waves offset by 90 degrees. Go look up quadrature encoding. \$\endgroup\$ Aug 23, 2016 at 16:50

I would suggest you to turn that printer on and measure voltages on those pins to find out which pins are for power (Vcc, GND).
And then use oscilloscope or multimeter to look at the rest of pins so you can see data that are going to the sensor and out of sensor. Or see voltages that sensor sets on some events.

If you already do not have those printers and PCBs than it's harder.
There are 4 wires. So, I would guess, that 1 is for Vcc and 1 for Gnd. That is the first thing to figure out. Ground is usually connected to largest areas. And 2 wires seems to be connected to resistors. I would suspect those 2 wires as data wires. So the last wire would be Vcc.
Start with 3.3V, then 5V.
I expect that when you figure out those power wires that you will get square signals from data wires (like from standard encoder).

  • \$\begingroup\$ The problem is that both of the printers got totally broken during the disassembling, and they have been thrown. \$\endgroup\$ Aug 23, 2016 at 12:06
  • \$\begingroup\$ Then you made your life a little bit harder ;) \$\endgroup\$ Aug 23, 2016 at 12:07
  • \$\begingroup\$ I noticed your update, thank you. I'll definitely try it out. \$\endgroup\$ Aug 23, 2016 at 13:06

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