Strange stepper and how to connect it

Hi all
i m new of arduino and electronics. I found a stepper motor from an old self-made plotter. It has 4 wires: red, white, blue, yellow.
I want to connect it to my arduino but i m not sure on what hardware to use as interface… I follow a lot of tutorial and find L2934 (H bridge) and ULN2003A… but what is the difference?

Another thing…Watching for online tutorial and datasheet i see that the color of the wires of my stepper don’t match with any stepper i see on tutorials… so i can t recognize them and don t know how to connect it!

Some tips?? :slight_smile:

Thanks and sorry for my bad english :-?

Hi, Vertex.

You should be able to find some information on the web in your primary language about steppers. Engineering departments at universities often have tutorials for their students.

The 4 wires mean that you have a “bipolar” stepper, that needs to be driven by the “H-bridge” driver. There is no standard for wire colors (that I know of, anyway), so it’s no surprise that yours doesn’t match. You will need to use a meter to find out which wires connect to which of the two coils. Then you will need to experiment to find out which way to connect the coils to make it work. That’s the way the world of surplus works: you didn’t spend the money to get a motor with a specification sheet, so you have to spend some time ;D

Do you have the other parts from that plotter? Maybe you can re-use some of the electronics from it, too.


I follow a lot of tutorial and find L2934 (H bridge) and ULN2003A… but what is the difference

A 2003 is just a current sink, that is it connects a load tp ground. This is not what you want. A H bridge will connect a load to ground or to plus, this is what you want, See:-

FYI: That workshop is good, but alas, the illustrations sit right on top of words, making half of the lesson hidden. (At least in IE8)

I do not experience any problems reading all text with IE8.

All text and illustrations seems to be just where it should.

Asking to who build the plotter I get some information about the stepper He said to me it is a BERGER type stepper. This is what he said to me: 1,7° per step Electrical charge: 200mA per phase Stator: from 30 to 40 ohm

1.7 degree steps is very unusual. Should that be 1.8?

he said me 1.7 degree or equivalent 3.6... I think also the stator resistor is too high... :o

I alway heard about 1.33 ohm resistor :o :-?

On the PCB I found two MC3479.. This should be the diver

1.8 degrees per step is 200 steps per revolution. 1.7 degrees per step is 211.7 steps per revolution. Given the way stepper motors are constructed, a non-integer number of steps per revolution is not possible.

Ah ok so it s 1.8 degrees because he said to me 200 step per revolution

In accordance with the stepper features that i posted: Can i use the motor with the L293D? Do i need a supply power?

I alway heard about 1.33 ohm resistor

There are some steppers (I have a few) that use a lot of current at a low voltage (thus the small coil resistance). But there are many that use higher voltages and lower currents, so the 30-40 Ohm is quite possible.

Yes, you can use the L293D: it's rated at about 500mA per coil, so it will work comfortably with these motors.

Yes, you will need a separate power supply for the motors. It's always "wise" to do so (motors cause electrical noise that you want to keep away from the rest of the system), but in this case it's "essential": the motors will probably need about 7-9V to run at full power.


Ok i think I've understood how to connect motor, power supply and arduino following the L293D datasheet and your useful suggestions ;)

Refering to this image

these should be the connections to do

Pin 8 : To power supply (7-9 volt) Pin 9,1,16 : To arduino 5V Pin 2,7,10,15 : To Arduino pins Pin 4,5,12,13 : To ground Pin 3,6,11,14 : To Stepper

is it ok??

Thanks a lot to all of you

Is there any risk if I do these connections?