Which controller?

First post! I am working on a project involving a number of devices; three servos, three DC motors, LED’s, and two steppers, all powered by an 8amp, 12v supply. The steppers have been a real thorn. SN754410 and ULN2003 run the bipolar and unipolar steppers on a breadboard powered by 12v, 500ma wall wort but overheat on the perf board. Would a Pololu controller overcome this problem? If so which would be best?


Welcome to the forum! The specifics of the parts you are using really matter. What are the current and voltage ratings of your stepper motors? Can your unipolar stepper motor be used as a bipolar stepper (how many leads does it have?)? If you are looking for suggestions for parts to control your DC motors, what are their stall currents? Also, I am confused about your power supplies; you first say everything (including your stepper motors) is powered from an 8A supply, but then say the stepper motors are powered from a 500 mA supply. Can you clarify this?

- Ben

The bipolar is 12v, 50ohm, 260ma per phase, four phase. The unipolar is small, six wire, and no data sheet available. I assume it can run as a bipolar. The DC motors are 12v, 500ma each, driven by TIP120. The DC motors and servos are running well from the 8amp, 12v power supply. As a preliminary test, I was running the steppers from a 12v, 500amp wall wart without a problem. After moving them to the perf board (12v, 8amp) they overheated using an SN754410/ULN2003 chip. Here is a drawing of the project. http://www.cappels.org/dproj/ledpage/leddrv.htm

I am skeptical that your bipolar motor is four-phase. What makes you say this? how many leads does it have?

Is that really the stall current? Where does this 500 mA spec come from?

By the way, what exactly are you asking? Are you just looking for a way to drive your stepper motors, or are you looking for all the other components you need? What is your main controller for the system?

- Ben

The data sheet clearly states “4 phase”. I am ONLY looking for a stepper driver. All else is running fine.

Do you have a link?

Here is the link http://www.datasheetarchive.com/stepping%20motor%20mitsumi%20M42SP-5-datasheet.html

I called your office an hour ago. You had just stepped out so I spoke to another technical person, who also seemed surprised the motor was four phase, but mentioned a wiring tutorial in your FAQ. I looked but didn’t find it. Probably don’t know what I am looking for. She felt the high current controller might work best.

Your datasheet link is not very helpful. I see four possible things I can click on, and the first one I tried did not have a diagram of the connections. Also, I am pretty sure it is saying “4 phase” because it is a unipolar stepper motor, not bipolar. It is not clear to me from the limited information I have seen so far whether this motor can be used in a bipolar configuration.

I believe you spoke to Claire when you called. This is what she was talking about:


- Ben

The motor in question has only four wires. Can it be anything but a bipolar? Here is a screen shot of the specshttp://www.datasheetarchive.com/stepping%20motor%20mitsumi%20M42SP-5-datasheet.html. Would you please advise how the wiring differs from a typical bipolar when connecting to the controller? I am going to order several of the high current controllers for testing. We shall see!

That is just the same link you posted before. Do you actually see anything useful when you click on it? In general, you should try to avoid those datasheet crawling websites like datasheetarchive.com and look for something directly from the manufacturer. A simple google search for M42SP-5 immediately turns up a pdf link from the manufacturer’s web site:

mitsumi.co.jp/latest/Catalog … sp_5_e.pdf

That datasheet says “4 phases” with a “2-2 phase excitation (unipolar driving)” method. I think both of these specs are wrong/typos/bad translations and you actually have a normal two-phase bipolar stepper motor. You should be able to easily verify with a multimeter that your motor only has two coils, and I expect our stepper motor drivers will work just fine.

- Ben