[MrWild]

I know there are the A?B encoders and they can be used in quatrature. There are A+/A-, B+/B- encoders that can also be done in quatrature. Not knowing the difference, I bought three absolute encoders for a very good price. Some on on eBay is saying you can wire Absolute the same as A-/A+, B-/B+ encoders. We're talking rotory encoders here, but I'm interestred if there is a place to read about the differences,or someone can tell me the differences so I am more informed next time. A good deal is only good if you can use what you've bought

[Al_The_Man]

I know there are the A?B encoders and they can be used in quatrature. There are A+/A-, B+/B- encoders that can also be done in quatrature.

Incremental encoders are usually all quadrature, they then can be used in native count (x1) or double (x2) or four times resolution (x4) they are all quadrature to begin with, it has nothing to do with x4 count (or the x2 for that matter).
They all usually detect a etched grating and photo/emitter/detector method using the moiré effect to enlarge the 'shutter' effect, and this results initially in a sine/cosine signals 90° apart, hence quadrature signal.

Absolute usually required a completley different interface as they out put a various multi bit wide data, some 8 bit, 12 bit etc. Also the code bit code can be in different forms, binary, gray code etc.
I found buying encoders off of ebay a crap-shoot, unless you know what you are buying and they should be new or NOS, if used, you usually end up with some duds.
Al.

[mackeym]

there's also sine encoders, which have very high resolution.

[unterhaus]

what brand and model absolute encoder?

There are absolute encoders that have quadrature tracks, as an example, on the electrocraft servomotors. Accurite makes some linear encoders that have an absolute track in addition to the quadrature tracks, basically they have an index track with the position encoded on them at intervals. I would think that quadrature would be an option on the electronics from some absolute encoders, it's trivial to add that functionality.