High Current Stepper Control

[tykom]

Hi All,

I'm starting a project to control a stepper-based locomotion system with RasPi (First RasPi project, have some experience with electronics, Arduino, etc.) but I'm having trouble figuring out which motor controller to use.

This is for a school project, so I had to order with a group where we got a load of these

Steppers

and I requested 3 of the Adafruit Motor HAT

The problem is that the steppers draw 2A and the HAT is rated at 1.2A per channel.

So a few questions:

Can I use these motors and just put a (large) resistor before connecting to the motor controller? Will sacrifice some torque, but would be cheapest solution...

Should I build my own using something like the A4988 on a breadboard? My worry with this is controlling it with a Python script, I chose the Adafruit one as they have Python libraries for it.

Other ideas?

Any help is really appreciated.

[experix]

The Gertbot has 4 H-bridges rated 2.5A, and you can certainly get H-bridges alone if you want to build your own thing. And there must be other boards out there that have bridges with enough capacity for you.
Your remark about putting resistors in series with the motors suggests you may have chosen motors that are more powerful than you need. They will also be more bulky and heavy. So maybe reconsider that. Anyway, better than putting resistors in series, reduce the drive voltage.

[P_Monty]

You could use a suitably rated power transistor between the output and the motors...

[tykom]

Just for community reference, I ended up using the heatsinks included here with this stepper motor running on the Adafruit Motor HAT. I attached the heatsinks to its TB6612s with Arctic Silver Thermal Adhesive and let it cure under a 50W desk lamp for an hour.

Haven't had a chance to measure the actual draw, but I had the motor stalled on a 2.4A power supply. It was definitely hot, hot enough that it shouldn't be in confined spaces, but didn't damage the HAT.