One of the things I need to do while working towards motion control projects is to practice some of the fundamentals. I’ve worked with many of the concepts and mechanisms professionally, but more from the support end. I haven’t touched the stuff for a few years now, and want to learn things at a more fundamental level. In order to do this my plan is to pull motors and mechanisms from recycled equipment (printers, scanners, etc.) and set up a few labs for myself along the way. Perhaps I’ll try to salvage some of the electronics as well with some good old-fashioned circuit bending. I should be able to at least reuse motor drivers that are found, but for now I’m going to rely on inexpensive motor driver kits to allow myself more freedom to experiment.
Through some discussion forums I discovered Pololu and their very cool little A4983 Stepper Motor Driver Carrier. These are carriers for the Allegro A4983 DMOS micro-stepping stepper motor driver which normally comes in a tiny 28-pin QFN package. Pololu has provided a nice carrier with a DIP form-factor that makes the A4983 manageable for hobbyists of all levels. With pinouts located on a 0.1″ grid the carrier can be used in breadboards very effectively. The micro stepping (configurable up to x16) is a great feature though to use the carriers at their full power capacity of 2amps some additional cooling is required. Heat sinking or forced air both seem to be used effectively by others.
- Small form-factor
- Micro stepping
- Adjustable output current with on-board pot
- Very reasonable priced at $12.95USD in single quantities (I bought 10 for $11.65USD each)
- Pre-assembled except for pins which are soldered in place in under a minute leaving the actual connection details up to the user.
- No option for mechanical mounting aside from the pins (you could of course glue them in place). I think it’d be cool if they had a couple of tabs with mounting holes in them. The tabs could be perforated to be easily broken off if the user wants them to be more compact.
- Mounting a heatsink could be tricky due to the height of support components around the chip. I’ve seen at least one person glue a nut to it, but I’m always looking for a better way. Ultimachine has these with a headsink included. Again, perhaps tabs could help with heatsink options.
As soon as I got my order of 10 of these boards direct from Pololu, I soldered up a couple of them with their SIP connectors and wired them up in a breadboard. Driving 4, 6 and 8 wire motors were a piece of cake with these as they’re bi-polar and they interfaced with EMC2 without a problem. Very quickly I had an old scanner mechanism with a small 4-wire stepper moving around and then a much larger NEMA 23 stepper. Not long after I had my old junk CNC moving around again (MUCH more efficiently). Over all, I have to say using these for the first time was almost anti-climactic it all went so well, but that’s a hugely good thing. I have real plans for these!