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Encoder Hacker Needed
« on: March 04, 2008, 07:01:48 PM »
Hi Folks,
I have a stepper motor that has a magnetic encoder on it. It has what looks like a small fine pitch gear on the shaft and a pick-up mounted adjacent to it with a small air gap. The head resembles the pick-up head on a cassette tape player....sort of.
Any way, there are 4 wires. 1 brown and 3 gray.  I assume that there is 5v+, A, B, and 0V.
What is the procedure to determine which wire is which? I've got a good Fluke meter.
Thanks for anything,
RC
Re: Encoder Hacker Needed
« Reply #1 on: March 04, 2008, 07:16:48 PM »
measure the resistance betwen all wire combinations and tell me.  if one wire has not resistance whit the others  verify this wire continuity whit chassis
i suspect this head has not suply voltage input and need amplification to get logic signals.

Josep

Offline Chip

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Re: Encoder Hacker Needed
« Reply #2 on: March 04, 2008, 07:32:28 PM »
Hi, RC

Sounds like a small Tack-o (Tachometer) to me, But they usually only have 2 wires.

No part # Hu!!, Seen some similar, on small servos

Give us the values, Chip
Re: Encoder Hacker Needed
« Reply #3 on: March 04, 2008, 08:58:39 PM »
Josep, it is connected to a PCB so you are probably right about the amp.
Chip, this is a Hybrid stepper/servo.
This is probably futile....here are the readings.   
Brn  to  #1        .329k
Brn  to  #2        .431k
Brn  to  #3        .321k
#1  to  #2        .315k
#1  to  #3        .431k
#2  to  #3        .324k

When the head is brought near the wheel these values roughly double.
Thanks,
RC
just an experiment....I can trash it.


Oh...I cut it loose from the pcb to check it.
« Last Edit: March 04, 2008, 09:01:46 PM by Overloaded »

Offline Chip

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Re: Encoder Hacker Needed
« Reply #4 on: March 04, 2008, 09:30:49 PM »
Hi, RC

What's the Part number on the IC' the wires go to ?

Any difference if you reverse the meter leads ?

Thanks, Chip

Offline Chaoticone

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Re: Encoder Hacker Needed
« Reply #5 on: March 04, 2008, 09:47:54 PM »
Might be able to find some info. off of the ICs here that will help.

http://www.datasheetcatalog.com/datasheets_pdf/L/M/3/3/LM339N.shtml

Brett
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!
Re: Encoder Hacker Needed
« Reply #6 on: March 04, 2008, 10:40:10 PM »
Reversed leads, no difference.
I'll try to send pic. Multi layered traces, I cant track them.
Hope you can make out the #'s.

Hey Brett, Excellent resource. Thanks. I'll save that.

I fried the inputs on this board. Cost more to repair than to replace..at least that what the dealer says.
I have an application for this encoder if it doesn't get too complex.
Optical ones are cheap enough on FleaBay.
If we're getting in too deep, just cut me off.  ;)
« Last Edit: March 04, 2008, 10:47:50 PM by Overloaded »

Offline Chip

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Re: Encoder Hacker Needed
« Reply #7 on: March 05, 2008, 12:16:03 AM »
Hi, Rc

I think this would be a go to E-bay solution for sure, Your not going to get a true A-B pulse out-ua this one.

Chip 
Re: Encoder Hacker Needed
« Reply #8 on: March 05, 2008, 03:14:33 AM »
judging from the logo on the smaller SMD chip fitted to the board this looks like custom chip jobie

Looking at the tracks I would think it translates the magnetic changes in a similar way as the newal linear encoders
Wetter it is totally passive or actually active is unclear, coolmuscle is not very forthcoming in info on it.
You could look for patents in their name, often explains a lot.

The larger IC is a standard NEC micro which likely deals with the motion and communications

I scoured the net and could find no data in the IC (expected)

interresting product though

JB
Re: Encoder Hacker Needed
« Reply #9 on: March 05, 2008, 06:50:33 AM »
Thanks for taking the time guys.
This one is history.
RC