Hey Terry.. I've got a handful of those little buggers, they are GREAT little steppers. VERY quiet and strong for the price. Using a ULN2003 to drive it, I just run a second 7805 for some extra +5v as my wall wart kicks out 2A (supposedly) so I don't put too much load on the Arduino's. Sorry to say I didn't buy them from you- maybe next time.
In any case, maybe you can answer this...
They are supposed to be 64 step with 1/64 reduction, which means it should be 4096 steps per revolution.. but the reality is that it actually is half that, 2048 steps, using the standard Arduino libs and the ULN2003 4-wire setup, in fact I'm using one of those boards. I've noticed in the forum this has been mentioned before but nobody seems to have an answer..in looking at the timing chart on your site, it looks like it's using half-stepping to get that number, while the arduino libs are set up to use two phases at once (full stepping). 2048 steps for one revolution is more than enough resolution, so it's cool.. just wondering. I'm just thinking that shifting out the bit patterns (it's 1-8 in binary on the leads to give it the stepping noted on the docs) would be not too hard and might be worth slapping a lib together for the motor to do just that. We'd lose torque, but the thing is geared mightily so 70% of the torque via halfstepping is probably still enough for most things. Academic I suppose, as like I said- over 2,000 steps per revolution is an awesomely tight motor, 4,000 is of dubious value- that's a ridiculously small step angle at .08 degrees. If you run, say, a wheel with a six inch circumference 2048 steps, that's .003" per step. At 4096, it would therefore be .0015- and I'd be questioning whether the gears can mesh that tight for that kind of tolerance.. Anything less than one degree per step is pretty good, these do six times that "normally".
Great little motors!
Eceela, make sure to read through the information in the Playground on the stepper library http://arduino.cc/en/Reference/Stepper
; that motor is a Unipolar stepper motor. I am using a ULN2003 chip, which is just seven darlington transistors per DIP, and darn cheap- a couple for a buck. I use one per motor, I am using those exact motors. I'd use a secondary power source to drive the motor power though, it draws a few hundred mA and the regulator on the Arduino gets rather warm. I run a second 7805 voltage regulator (another 50 cent item) to provide the motors with their own 5v supply. Running it from the 9v wall wart directly is not nice, the little beastie gets pretty warm. I guess you could do some PWM, but a 50 cent regulator is just easier. Do yourself a favor and get some 7805's, a few LM317T's (adjustable regulators), and a handful of the ULN2003 chips, they are just so darned useful.. and you can't find darlington transistors singly for the price you'll pay for the array of them. I also am going to see if there's an easy way to "convert" the UL2003 module (the board Terry sells) to two-wire control without using external transistors. Should be do-able with a couple of 1k resistors and a little creative soldering.. but I digress.
Probably the best deal out there when it comes to steppers- ULN2003 + those motors is a precision positioning system for under $5.. that's impossible to beat!
Now someone (maybe soon) needs to take four of them (XYZ and rotation table) along with a high speed brushless DC motor and a dremel bit and make a supertiny CNC milling machine of VERY high precision..