Looking at the specs, I saw it runs on 5VDC, which (IIRC) is the voltage that the Arduino pushes. Does that mean I don't have to use a driver circuit with it? If I do have to, can someone explain why?
Admittedly, I'm still noob when it comes to stepper motors. I have worked with servos on an Arduino, but I know those have the circuitry generally built into them. Also, if I do need to put something together, can someone tell me my best option for how to construct the driving circuit (as I can't tell what would be best for my stepper from the many layouts I've seen online)?
yes, the second you apply a mechanical load on a motor its current draw dramatically increases well beyond the realm of the cpu's abilities
if you just want to hook it up and figure out how it works without a driver you might get lucky, but it seems like unnecessary risk (and you will still need to provide protection from the motor to arduino anyway for back emf currents)
Okay, I think I get it. Though the voltage is only 5V, it is the current that is what needs the help? That makes sense...I always underestimate the importance of current in circuits like this.
As far as the emf currents go, is that because of the magnets moving past the coils, acting almost like a generator?
I think I'm starting to understand the reasoning behind the driver circuit...now the only question is how to make it. I've been looking but it's hard to tell what is or is not overkill for such a small stepper.
I saw it runs on 5VDC, which (IIRC) is the voltage that the Arduino pushes. Does that mean I don't have to use a driver circuit with it?
Not necessarily: I have some much bigger 5V steppers that draw 2.5 Amps. Even a motor shield can't handle those. You have to consider both the voltage and the current.
The motor(s) you bought appear to be the same as some I've seen at one of my favorite surplus dealers. They have an example circuit on their site that shows it being driven by a 74HC365, whic suggests that it might have a low enough current draw to be driven directly by an Arduino. Might. It's pretty iffy, though, and I wouldn't risk blowing up the CPU chip by trying it.
If you want to try driving the motor on the cheap, I'd suggest using a 74HC365 like the example circuit: that way, if the magic smoke gets released from a chip, it'll be cheap magic smoke. You should also add protection diodes to help keep the 74HC365 from getting fried.
Ok, I think I'm getting it. If I use the 74HC365, then:
a) do I need all of the other stuff besides the 74HC365 in the example schematic? I can't really tell what the purpose of it all is. And
b) where would I put the protection diodes to keep the 74HC365 safe? Logically thinking, my guess would be between the IC and the stepper motor, but I don't want to hang my project (and my money!) on a guess.
I'm really just looking for the most basic application, as my project really only needs speed control and uni-directional movement. I suppose I could probably even modify a servo if it's going to be that much of a pain, but I want to try to learn something from this.
do I need all of the other stuff besides the 74HC365 in the example schematic? I can't really tell what the purpose of it all is.
The other parts generate pulses that you'll do in software. You don't need them.
Here's an example of connecting the protection diodes. Yes, the diodes are "backwards": the idea is that, if a voltage spike goes way above 5V or below ground, the diodes provide a path for the extra energy that doesn't go through the driver chip in a way that might damage it.
You'll want to put a pair on each of the three wires going from the 74HC365 outputs to the coils.
If you put a single diode across the coils of this motor it will not work. This is because what you have is a 2 phase bi-polar / quadrature motor. This means that at some parts in the cycle current will be going in both directions through the coil (not at the same time of course) . This means a single diode will sometimes be conducting an in effect shorting out the coil.
In this case you need four diodes per coil. From each end of the coil you have two diodes, a cathode and an anode. Then you put the other end of the diodes up to the rails with the free cathode going to + voltage and the anode going to ground.