It was quite a while ago that I obtained my SLAm stepper, thanks to Mr. Newton , but I just hadn’t had the time to give it the proper trial it needed. The time has finally arrived! More information “straight from the source” can be found at http://www.piclist.com/techref/io/stepper/SLAm/SLAm_bld.htm. This is the same place I got my Linistepper from. They have a Linistepper Version 2 out now, and although I haven’t tried one out, it looks pretty nice (with addition of things like the screw-down connectors on the SLAm stepper: a wonderful addition). This is a chopper-driver, so for those of you looking for something smoother might want to stick with the Linistepper.

I think I had more fun playing around with this driver, but only because of the cool new things I learned along the way, but more on that later.
This kit literally only contains a handful of parts and was a snap to put together; I had it assembled the same night I got it. The parts were packed nicely, and as high-quality as their Linistepper. I have the parts laid out in the pictures below:

The directions are easy to follow. Everything fits together nicely, and there is enough room for even an amateur like me to do a decent soldering job.

A large heat-sink for the SLA chip doesn’t seem to be necessary for smaller motors (small as in current). I used this fancy little green thing, which I think may have come off of a north-bridge a number of years ago. It certainly helped hold the chip in place while soldering as well.

Once you get the last few connectors on there, this thing is ready to go!

Now all you need to do is hook some stuff up to it. The motor wiring is conveniently handled by the screw-down connectors, and I think this might be one of the most wonderful things about the board! It was such a pain manging all these flimsy wires on the last motor I used, but here, all you have to do is clamp them down and they’re not going anywhere.

The connections for the V+/Ground/Step/Direction/Enable are handled by a 10-pin connector (5×2 pins). I found that I had more spare wires that fir this than I though (they’re pretty common on motherboards). It was at this point, however, that I remembered one of the reasons I hadn’t gotten back to playing around with it for so long: I didn’t have anything pre-set up to send stepping signals… What I used for the linistepper wasn’t working anymore (even for the linistepper). I believe this to be due to some bad soldering when I tried to attach some lead wires. Anyways; no step signal, no turn.

Enter the 555 timer!

Or in my case, a 556.

Here is where the next real bout of fun started! I’ve never played around with these 555 chips before, so it was a fun learning experience to learn about it. A 555 chip is a small integrated circuit that can be used as a timer (here to send out a square-wave stepping signal). The circuit designs for these are really simple, and all the parts are cheap and easily found. (The 556 chip is simply one chip with two 555′s built into it).

I found this page really useful when trying to learn a little more about these and draw up a circuit myself:
http://www.kpsec.freeuk.com/555timer.htm
Note: For the square wave you need the astable mode

I picked up some of the loose parts from the closest Radio-Shack I could find.

Unfortunately (and disappointingly) they did not have and solderless breadboards, so I had to get a small circuit board and make it more permanent. I think I would recommend a breadboard (unless you want to build a permanent circuit) if for no other reasons than this next picture:

I’m lucky nothing shorted. Do note the massive 1MOhm potentiometer to the right side. Once you have a set capacitor, the frequency of the output is determined by the resistors. Along with 2 fixed resistors, I added this variable one so I could tune the frequency of the step. This was especially important since I didn’t know what would work for my stepping motor! A day and a rats-nest of wires later, I had this thing ready to go!

I have a couple of movies of me trying this thing out ala YouTube:
http://www.youtube.com/watch?v=XWEoNorW-Ks
http://www.youtube.com/watch?v=meKB1x1Yr4A

Once again, I had a lot of fun playing around with this, and ended up learning a lot more than I thought I would! I would highly recommend playing around with a project like this if you get a chance.

Some other neat things about this driver is the holding-mode. When powered and the motor isn’t being sent a signal, the motor is held it place. Since I’m messing around with PICs right now, I hope to trying and program one to step the motor once and then take a reading from a sensor; repeat until some condition is met. With the hold mode, I know that its not going to slip, so if I know how many steps the motor took, I know the total rotation of whatever I’m turning. Perhaps I shouldn’t be as entertained by that as I am, but regardless, I hope to have more about this up when I write up my experiences with the Junebug PIC programmer/testboard I bought from from http://www.blueroomelectronics.com around the same time.