Getting a Stepper Motor to Turn

Hi all,

I am virtually a beginner at electronics and I am having a go at controlling a stepper motor using a PIC14M. The 3 stepper motors I have I salvaged from old printers.

To make it easier for those willing to try to answer my question, I have put all I think is relevant into a PDF explaining the specifications of my motors and pictures of the circuits I think I need. So please read the PDF titled "An Effort to get a Stepper Motor turning".

I have also attached the datasheets for my stepper motors I want to use.

If there is anything I missed out, please don't hesitate to reply!

Thanks so much for the transistor help I received the other day!

Chip datasheets

Since I can only upload 2 PDFs per post, I thought I would upload the datasheets for the two motor driver chips that I was thinking of using.

At the moment, as you will read in my "report" in the previous post, I think I will be using the L293D, but my big question is, will the L293D circuit from Picaxe Manual 3 be able to handle my stepper motor specifications? (I have included a picture of the circuit in the PDF attached to the last post titled "An Effort to get a Stepper Motor turning".

Thanks!

If they are 4 wire devices they are definately bipolar motors hence the ULN2003 will not work, you must use the L293D type circuit.

This is because with bipolar you must be able to reverse the current in the two coils to get the correct stepping sequence, only the L293D can do this.

Bipolar - The stepper motor turns because the rotor is a magnet and the coils around it are energised in such a way to attract the magnets. If you energise each coil in turn (simple way to think at present) then the magnet will follow the energised coil and turn.

Working out the wiring is tricky and a multimeter to check resistanc will hel you here. After that a bit of trial and error.

I find that the printer steppers I have rescued need quite a lot of current and possibly voltage to drive then effectively. So your picaxe battery supply may not be good enough although you may get some turning going as an experiment.

e.g. older Hp deskjet printed use a 30 or 40 volt PSU supplying perhaps 2 amps.

L293 can supply 600 Ma with a peak of 1.2A for the L293D - they have thermal shut down so your not likely to harm them even with a short circuit but they may appear not to be working if you overheat them.

Other than that the example software in the manuals works fine.

http://www.cs.uiowa.edu/~jones/step/ seeme to be the web bible on stepper motors and their use.

"Rescued" stepper motors are generally power hogs! The associated wiring, power supplies and driver electronics can daunt. If you're just learning about stepper basics then go for very small ones- I've found the Electronic Goldmine offering below (presently just US$1- but serious p&p) are perfect for this.

Thanks for the help!

Hi all,

Thanks for the help so far. As it seems as though the L293D Motor Driver is the only way, I will buy that on Monday and hopefully get the stepper motor to work!

I am pleased that the L293D has a thermal overload!

I will be powering my circuit by a DC 5V 800mA transformer that originally powered an internet router. Do you think that will be able to cope with the stepper motor load? I am pretty sure it will cope...

Thanks

Me thinks you should use a L298N .

stepper motors from used printers will require more current
than a l293D can handle.

Kym