Encoders

Hi,

I'm looking for some cheap optical incremental encoders. (Cheap is £15-20 - I have heard that you can get them for around $30.)

2000 PPR, able to fit a range of different motors. (Will be using them on the back of stepper motors, both NEMA 23 and NEMA 17.) Metric shaft size.

2 channel quadrature.

I'm in the UK so a UK supplier is ideal.

Any ideas as to where I could get them from ?

I don't know i'm afraid, but why encoders + steppers? If you're doing closed loop control, get cheaper dc motors, if you're doing open loop, you don't need feedback :s

I'd just like to experiment with closed loop steppers - You can essentially turn them into AC servo motors with a very high pole count, which means that you don't need to gear them down. That and stepper motors are much cheaper than AC servo motors.

Even with DC motors, I'd still need a source of cheap encoders so the same question still stands for that route too.

I'm thinking about doing the same thing. I like the challenge and learning of trying something like this. If successful then it will also give great insight into the performance of the motor and drive electronics.

The lowest cost optical encoders I know of is from Renco:

Renco R35i encoder

If you know of lower cost alternatives for an optical encoder I'd appreciate a pointer. You could look at CUI's AMT encoders also:

CUI AMT Incremental Encoder

These encoders are small, versatile, and low cost... but they are touchy and require careful alignment for correct operation. Once really nice feature is that they adapt to virtually any shaft size (buy the kit... I think it has a "V" in the part number):

Assembly video

You can find these encoders at Digikey.

TC

Thanks !

I couldn't find the R35i encoder on DigiKeybut the configurability of the CUI AMT encoder is ideal for me.

I've placed an order for one so will see what it's like when it arrives. (The encoder is ~£16 on DigiKey - Came to a total of ~£34 with shipping and a cable.)

I ordered:
102-1307-ND
102-1309-ND

They are by far the cheapest I've seen and the fact that you can easily select the line count and use it on multiple motor sizes is a real bonus. Shame it doesn't have 2000 PPR as an option. (A 2000 PPR encoder on a 200 step stepper motor is essentially like using 10x microstepping.)

Thanks again.

Don't forget that with quadrature you get 4 edges per line. A 1000 line encorer gives you 4000 edges per revolution.

TC

It's quoted as PPR on the site so I'd assume that is in edges, unless I'm miss-understanding it ?

Edit: Oh, looking at the datasheet, you're right ! That's awesome news, thanks.

Edited 1 time(s). Last edit at 04/29/2012 07:19PM by yngndrw.