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I've recently torn down and old printer as a learning experience and to maybe build something kinda fun out of it. As many will know that have taken apart printers, most newer ones have ceased using stepper motors and have started using a system of regular dc motors mixed with photo interrupters and optical strips to tell distance. A particular one photo interrupter I've come across a lot now has six pins out of its small black package. 2 I have determined are for the infrared led and the other 4 are for the phototransistor. Sadly, I can't find this little photo transistor on the internet and have instead resorted to the wonderful people here for some help. I removed it from the housing, figured that'd help a lot.

Here's a picture of the phototransistor removed from the photo interrupter housing.

Cosmic Floppy DIsk
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    Go to your favorite electronic components distributor (wonderful people) and buy a pototransistor with a known datasheeet. Cannibalizing components out of old consumer electronics doesn't make a lot of sense nowadays (at least in the developed world it doesn't). More on that here. – Nick Alexeev Jul 13 '17 at 22:00
  • @Nick Alexeev Not everyone is in developed world. – AndrejaKo Jul 13 '17 at 22:10
  • @NickAlexeev Any distributor you'd recommend? – Cosmic Floppy DIsk Jul 13 '17 at 22:11
  • Hobby grade: Jameco, SparkFun, Adafruit, your local electronic supply store, even RadioShack if they are still in business. Professional grade: DigiKey, Mouser. [All of these are in the US. The list would be different for other regions.] – Nick Alexeev Jul 13 '17 at 22:17
  • It isn't a simple photo-transistor: it is an integrated circuit, perhaps processing an array of silicon photosensors. Some types generate in-phase and quadrature outputs, but that's a wild guess. – glen_geek Jul 13 '17 at 23:46
  • @glen_geek so what your saying is it's not worth trying to figure out? – Cosmic Floppy DIsk Jul 14 '17 at 00:02
  • Value your time as you see fit. Only 4 connections, it may be possible if you're careful. The possible chip function it performs is large. Example: a 3-lead TV remote receiver only responds to a short burst of 38 kHz infra-red pulses. You'll likely not know if you've destroyed it by probing with voltages/currents. – glen_geek Jul 14 '17 at 00:58
  • Since its for position encoding I'd guess it's a dual photo-transistor of sorts which will provide quadrature information. Since it is part of a commercial photo-interrupter it may well be a custom device though. – Trevor_G Jul 14 '17 at 14:48

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