Can anyone recommend a motor of about the same size, voltage rating, and torque as this
http://www.robotshop.us/rbsoy03-soyo-unipolar-stepper-motor.html
but as a bipolar stepper?
also... I am a bit confused about how one would control such a motor... i found the tutorials, but i have no idea what a ULN2003 (or 2004) is... so can you also include which of these i would need with the motor you suggest (and perhaps a place to buy these chips, i couldnt find any place that sells them on google, all it gave me were spec docs)
// one more question:
could i run two of these motors (lets say two of the ones above, or if it makes a difference, two similar spec'd biplor motors), an arduino mega, an lcd, a few buttons and about 6 servos with a transformer that outputs 12v @ 600mA (the wiring, im guessing, would involve splitting the output between the motors, each having their own 12v gnd wires, and the arduino)?
The only part I can help ya with is how to power the steppers...I ran into a similar situation in that I could not find the ULN2000x (which if memory serves is a Darlington array)....The two ways I have powered my steppers(which are 24V, 3.5A motors) is basically making my own Darlington array with tip31 transistors, and recently switched to 510 MOFSET transistors (they seemed to handle the power better)....if you want more info on the exact circuit, google "tip31 stepper circuit" or transistor stepper circuit. Good luck
I am a bit confused about how one would control such a motor.
See:- http://www.thebox.myzen.co.uk/Workshop/Motors_1.html and from there look at Motors 2, 3 & 4.
could i run two of these motors
Yes it is just a matter with feeding it the correct pulse rate with the software.
This article helped me a lot on driving a bipolar motor, found in a cd rom drive:
http://www.tigoe.net/pcomp/code/category/arduinowiring/51
I used the two-wire circuit with L239. Maybe you have confused the unipolar and bipolar circuits. For a bipolar a h-bridge is a lot better, and I haven't seen a bipolar driven with darlington arrays yet. If I read correctly the motor is 12V 0.4A so this is within what L239 can handle, but in my case it heated quickly so maybe a heatsink or a better driver is something necessary.
For the software part - you can use directly the code provided on the site. Or using some of the timer libraries to drive the motor using your own stepping sequence.