Salvaging optical encoders


For fun I like to collect free printers and salvage parts from them. This includes things like motors. Another parts I like to salvage are optical encoders. The issue with them is that I'm not sure how to power them up. I understand there are 2 pins for the data; but what voltage do I provide on the led and sensor?


As input to an opto based device You apply current, some milli amps, not voltage. The out usually is a transistor that conducts when current flows through the diode.

Can you please provide a rough schematic? That would be greatly appreciated.

Do you have a DMM with a diode test function?
You can use that to check if the emitter is just a LED or a LED and series resistor.

As you have probably noticed, some interrupters/encoders have E and S marked in them to show which element is which.

Can you please post some pictures of the interrupters/encoders that your have found?

Thanks... Tom... :grinning: :+1: :coffee: :australia:

I tried the diode test function before hand; I get 0.75V in one direction; and 1.3V in the opposite one. Also I have a conflicting reading between my DMMs. Which measurement is the forward voltage of the diodes?


Can you please post a picture of the encoders you are measuring?

Thanks.. Tom... :grinning: :+1: :coffee: :australia:

Here are some of the optical encoders I salvaged.

When taking photos, please take the parts outside into full daylight (but not direct sun) and ensure the photo is perfectly focused.

Unfortunately, in your dungeon, we cannot see any detail. :woozy_face:

At least some of them appear as "quadrature encoders" from print head positioning system (and probably there was also a plastic strip with micro-lines printed on it) ... if so, they have probably 4 outputs (can be 2 or 4, depend form the resolution), usually photodiodes, and the leds can be in serie or parallel or serie/parallel, this depend from the manufacturer (if there are some part numbers printed on them and they are not custom made, is possible to search for datasheets).

Except this, from these images i cannot say other, sorry.

Not sure if this helps;

Tom.. :grinning: :+1: :coffee: :australia:

It is said that you cannot make a silk purse from a sow's ear. :face_with_raised_eyebrow:

Let me know if this is good enough.

Great resolution. :+1: :+1:

Tom.. :smiley: :+1: :coffee: :australia:

I have a lot of encoder wheels and strips laying around.

This is a very smooth optical encoder I plan to use on my SDR receiver. V+ and V0 pins for the internal Led, then phase A and phase B which alternate with a quadrature encoding disks. Signswise Incremental Optical Rotary Encoder for Arduino 600P/R Wide Voltage Power Supply DC 5-24V 6mm Shaft Quadrature : Industrial & Scientific

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