Need help with identifying and specifications of this stepper motor (for Rpi/Arduino)

[Siddhartha RT]

Hey guys,

I'm working on a side project which needed a couple of stepper motors. We picked them up from scrap, and I'm not able to work it with either Arduino or RPi. I used a motor driver ICL298 HBridge, but I'm not able to drive it nicely.

Can you guys please try to identify this motor? I'm sure many of you have worked with such motors - I'm new to this stepper motor world.

Thanks.

The specification is also included in this album: http://imgur.com/a/oFeJ5

 

[MicroMe]

From your link it is 3.84V 0.8A rated per phase.
As your plug only appears to have 5 leads, then I suggest it is four phases (coils) connected to one common lead. Here is a possible wiring diagram (ignore colours as they change with each manufacturer and production run)
https://www.dropbox.com/s/edkybt46q1ub2d8/28byj-stepper-motor-wiring-diagram.png

You can identify the common lead with an ohm meter by measuring the resistance across two leads at a time, if you find one coil/phase the reading will be 3.84/0.8 ohms i.e. 4.8R
If you bridge two coils it will be 9.6R.

So the process is find two wires that give a reading around 5R, then measure from one of these leads to every other pin, if they all read 5R then you have found the common wire.
If any reading is about 10R then it is the other lead that is common, but measure all the wires with respect to that just to confirm.

You next have to determine the phases and that is by trial and error until you get smooth rotation.

The 298 H bridge chips are normally for DC motors, not steppers, however I have seen a pair of chips driving a stepper motor, but this requires the 4, 6 or 8 lead stepper motors. If yours is 5 lead as it appears in the picture then it cannot be driven by this circuit as far as I'm aware.

You need a circuit similar to this
http://www.geeetech.com/wiki/index.php/Stepper_Motor_5V_4-Phase_5-Wire_&_ULN2003_Driver_Board_for_Arduino

EDIT. Your drive needs to unipolar (not bipolar) which basically shorts each phase to ground in a sequence with the common point at a positive supply voltage. There are several drive options, but these are unfortunately the least energy efficient type of motors.

The link you posted has 6 (or 7) leads, so treat my advice above with caution until you can confirm the coil arrangement.