Society of Robots - Robot Forum
Electronics => Electronics => Topic started by: Pyro on September 06, 2009, 02:58:02 AM
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I need to build a 3-way stepper motor controller for Unipolar stepper motors. Just for a reference, I'm thinking of going with 3 of these motors: http://www.alltronics.com/cgi-bin/item/28M065/55/Lin-Engineering-5718M-15-09-unipolar-stepper-motor (http://www.alltronics.com/cgi-bin/item/28M065/55/Lin-Engineering-5718M-15-09-unipolar-stepper-motor) . They are about 130 oz-in (~9.4 kg-cm) each, and are 1.3A per coil.
I want to build this for as little as possible, and as simply as possible. I just need a simple, accurate, and inexpensive circuit to drive 3 of these motors. The only problem is, it seems there's about a million different designs out there, and they're all "better than every other design". I am a beginner when it comes to electronics, but I am confident enough in my abilities that I want to build this circuit myself.
By trolling this website a bit, I've come across things such as the EasyDriver v3 from SparkFun (http://"http://www.sparkfun.com/commerce/product_info.php?products_id=8368#"), the PhidgetStepper from Active Robots (http://"http://www.active-robots.com/products/motorcon/stepper-phidgets.shtml"), and designs to make your own Here (http://"http://electronics-diy.com/electronics/stepper_motors.php") and Here (http://"http://linuxgazette.net/122/sreejith.html"). Two designs that I found prior to this thread that I was consider are the Tachus42 from PMinMO (http://www.societyofrobots.com/"http://pminmo.com/3axis/3axis.htm"), and this Easy-to-build Stepper Motor Controller on Instructables (http://"www.instructables.com/id/Easy-to-build-CNC-Mill-Stepper-Motor-and-Driver-ci/").
So pretty much I just need to recommendations and guidance on how to go about doing this. Thanks in advance :)
- Pyro
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Why not buy one?
I mean, if you don't value your time, sure build one . . . but otherwise if you spend 10 hours making/debugging one, at minimum wage, thats already like $75 - twice the cost of buying a professional/reliable version :P
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If you can find me one for ~$50, I'll consider it. I just wanted to build it for something to do because I have easy classes right off the bat this year at school and I know I'll have nothing to do. I also wanted to expand my knowledge of the workings on electronics. But as mentioned above, if the price is right :)
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Those are some pretty nice steppers for the price. I think 130oz is good power to have for hobby cnc routers. (I assume it is for that, maybe I am wrong.) Some people throw as much power into as possible but it only makes the motors, control and mechanics more expensive!
If you are into CNC you can look at my homemade CNC at http://www.colinmackenzie.net (http://www.colinmackenzie.net) . I am very partial to the Gecko stepper controllers, there are a lot of nice features on them. Be careful of a lot of controllers, especially the ones sold on ebay, they state the max amperage of the parts from the datasheets but it's not a true reflection of what they can truly source. (I got jammed on that one, my 1.5amp steppers were killing my L293 based controller rated at 3A.) Geckos and Vipers are instead somewhat under-rated and use FETs that specify around 20amps or more.
If you are in to spending the time making your own from an instructable that's a good exercise, but it's definately not a savings from the time is money standpoint by any means. Make sure the schematic or pcb source is good too. I've found motor control circuits that just couldn't work online.
C
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You can find tons of unipolar stepper motor drivers above 1.5A here:
http://www.google.com/products?q=unipolar+stepper+motor+driver (http://www.google.com/products?q=unipolar+stepper+motor+driver)
for example:
http://www.virtualvillage.com/stepper-motor-controller--driver/sku006408-001?utm_source=googlebase&utm_medium=shcomp&utm_campaign=Stepper%20Motor%20Controller%20%20Driver (http://www.virtualvillage.com/stepper-motor-controller--driver/sku006408-001?utm_source=googlebase&utm_medium=shcomp&utm_campaign=Stepper%20Motor%20Controller%20%20Driver)
http://www.robotshop.ca/es1000-stepper-motor-controller-1.html?utm_source=google&utm_medium=base&utm_campaign=jos (http://www.robotshop.ca/es1000-stepper-motor-controller-1.html?utm_source=google&utm_medium=base&utm_campaign=jos)
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I forgot to mention those are 8 wire steppers (as pictured). That means you can wire up as bipolar or unipolar. Go with bipolar wiring and controller.
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If I were to build my own controller, should I build the Tach42 (http://pminmo.com/3axis/3axis.htm), Tom McWire's design (http://www.instructables.com/id/Easy-to-build-CNC-Mill-Stepper-Motor-and-Driver-ci/), or the overly simplistic design shown Here (http://electronics-diy.com/electronics/stepper_motors.php)?
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Could always look here http://www.societyofrobots.com/member_tutorials/node/120 (http://www.societyofrobots.com/member_tutorials/node/120) for theory, circuits, software etc.
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Thanks for your input. I think I'm just going to buy a kit from HobbyCNC, as it seems like the easiest/cheapest approach as of now.
Kit can be located here: http://www.hobbycnc.com/products/hobbycnc-pro-chopper-driver-board-kits/ (http://www.hobbycnc.com/products/hobbycnc-pro-chopper-driver-board-kits/)
I am considering working on designing some drivers as a little side project though, but that'd be pushed back to 3rd or 4th on my projects list :D
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I got into a road block with my phidgets 0/16/16 board to control a stepper
because the bipolar stepper needs polarity reversal.
So I built a stepper controller just using the L298N and LM317T example circuits
from the datasheets. Now I have a problem with insufficient torque at 1.2A 9.6V
with my stepper motor. I'm not surprised.
Robot running from Phidgets board using L298N stepper chip (http://www.youtube.com/watch?v=8OrnzUotS_Y#)
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That's pretty cool :)
I've pretty much decided on which drivers I'm using (well, I'm down to 2. Good enough) :)
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You know if you do not have to reverse polarity, you can run
motors directly from that phidgets board up to 2A (30VDC, I think),
without a driver bridge like L298N.
You just need software to time the on/off sequence.
I think with unipolar steppers you can do that.
You could try it with a battery to prove it.
Moving the motor in the opposite direction would not be possible.