| The linistepper stepper motor driver |
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| Written by Mark |
| Thursday, 12 January 2012 05:22 |
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Here is my experience of assembling a linistepper stepping-motor driver. Stepper motors are useful when you need precise control over a distance traveled. They have their advantages and disadvantages over different types of motors, but I'm not going to get into that right now. After a bit of research I decided this driver would work great. Some pro’s of this kit are that it’s cheap and it’s open source (you can download the schematic and build it yourself if you want!). I do not have an extensive background in deciphering electronic schematics, which is also the reason for this "guide". This kit is not for the "faint of heart"; you should probably have an idea of what you want to do with the motor, have the patience and ability to solder electronic components, the patience to troubleshoot electronics components, and the patience to interface this thing with some time of software. That is, of course, unless you are like me. When I first got this kit, I had never done a lot of soldering; even less so with smaller electronics components. I don’t have even one of the 3 P’s (patience, patience, and more patience). Also, I don’t even have a specific implementation for the motor yet; BUT I do know that I will need one, so why not get a head start, right?! The instructions that come with the kit are excellent; therefore it is not my goal to provide a detailed walkthrough of how to assemble this this kit, but merely to give my experience of assembling it; an example that someone without a background in things like this can actually manage to pull it off. I order my kit from the linistepper’s main website (see link above). I ordered the linistepper kit along with the additional kit for a power source, and attachments to a computer serial port. I will be using an old PC power supply for now, but for my main project, I do not know if I will have a regulated power supply handy, which is why I opted for this extra kit that adds on to the linistepper. Not long after, my package arrived in the mail:
A picture of the box it came in isn’t particularly interesting, but it was a little beat up (it did travel across the USA to my doorstep). I only show this to mention that the kit seems pretty solid (good quality) and a little normal-to-rough handling in the mail isn’t going to break anything. All of the components are packaged quite nicely as well;
Please note that the cat is not included in the kit.
The PC board they have printed seems very nice. It feels very durable, and they have screened the components on the board itself to help with assembly. I have definitely bought whole products that had cheaper components than this thing. I jumped right in and started putting the appropriate resistors in place while bending the leads behind the board to keep them steady.
Once I had enough in place, I started soldering. I will now say that the lack of a fine-tip for my soldering iron is the reason for the epic failure of my previous attempts at soldering things. Abandon all hope ye who don’t have one. I have since bought a nicer soldering iron, and I can't recommend strongly enough that you get one too. After a few clips with the wire cutters, this thing almost looks professional. Almost. In a DIY kind of way.
The linistepper does not come with a heat sink; this is something you have to provide yourself. But seriously, who doesn’t have some old CPU heat sinks and CPU thermal paste laying around?
After finally getting to use my metric tapping set, I had attached the heat sink and board.
The biggest problem I had when assembling this kit was attaching the transistors to the heat sink without them grounding out. The kit comes with the appropriate plastic spacers for the screws and mica spacers for the transistors, but I think I was sloppy about it the first time, and haven’t been able to get it right yet. I advise you to be careful in this step! I also get the feeling that the target audience for the linistepper driver uses these things for devices that are much more motor-intensive (like CNC machines). I don’t have the transistors attached to the heat sink, but for my run times so far this thing doesn’t heat up much at all. I don’t think this is recommended! This also leads me into my next bit of advice… Have a proper stepping motor ready!
(Corrected: I had misspoke about the type of compatible motors. The maintainer of the linistepper pointed this out to me, and mentioned a site with a list of known working motors)The Linistepper is compatible with 2 phase, unipolar ONLY motors with 5 or more wires. If you don’t yet have a motor, there is a (growing) list of good motors for the Linistepper on their website at http://techref.massmind.org/techref/io/stepper/linistep/motors.htm I managed to pull out a 5-wire color wheel motor out of one old contraption to test this thing out (movies at the bottom of the page). Eventually wanting to plug this sucker into a computer, I built a bit of a base for the components out of some scrap wood laying around.
I have a couple videos of my first attempts of getting the motor running without (1 and 2) and with a computer (3). They are hosted on YouTube. The quality isn’t that great (I took the recording with my Blackberry, at the time), and the conversion to flash probably didn’t make it much better.
For interfacing it with the computer, I used the LiveCD for linuxCNC, which is based off of Ubuntu with the real time patches applied to the kernel.So in the end, I managed to assemble the driver (with the help of the excellent provided instructions), test it (with some spare parts) , and hook it up to the computer (thanks to linuxcnc)! If you are interested into getting into something like this, and want to learn a little along the way (i.e. not buy an assembled box with the controls built in), then I highly recommend the linistepper.
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| Last Updated on Friday, 20 January 2012 12:35 |
