Hello all,
I received this with my arduino kit and can't really work out what it is.
I'm reffering to the smallest board pictured here in the middle, below the 3 large ones.
Thanks
Well it is not a very detailed picture but it looks to me like some sort of buffer board for driving relays and LEDs. Is that chip a Darlington driver? Google the chip number on it to see.
That small board is a stepper motor, driver, but 2 regular DC motors will work too.
Oh ok, thanks heaps for that!
I see now that the kit I have also comes with a stepper motor whose connector plugs directly into the little board. Figures! 
One question then, what is the difference between a servo motor and a stepper motor? Would a servo be considered a digital version of a stepper which is analogue?
Would a servo be considered a digital version of a stepper which is analogue?
Kinda. a servo has a potentiometer inside which is able to keep track of where it is and also allows the user to tell it to stop at a certain degree. A stepper can do the same but it requires some math to figure out how many steps it takes and then convert that to a degree. Not all steppers are the same, some take bigger / smaller steps then others.
Also a big difference is what happens when you move a stepper. If you don't have anyway to keep track of its location(angle), it's going to get lost and it wont be able to correct itself. Whereas a servo being that it already has a way tracking its location, it can return back to a certain degree if it is ever moved.
Steppers allow for torque, but are not good at keeping track of where they are, and likewise for servos.
AutoElecHack:
One question then, what is the difference between a servo motor and a stepper motor? Would a servo be considered a digital version of a stepper which is analogue?
Well, a stepper is more like a digital device. you move it in discrete steps. You supply voltage to the coils in a series of different configurations, and it causes the motor to move a very small amount (some will move less than 1 degree per step).
A servo is more like analog, in that you supply a voltage, and the motor begins to move. A servo requires feedback to tell the controller where it has moved to. This can be in the form of a shaft encoder (which can show a direction and amount of movement, or, alternatively, an absolute position), or a linear encoder that can tell the controller how far the moving part that is driven by the motor, has gone. A potentiometer can be used to show position, but it's not common. The controller uses the position information to speed up, slow down, or stop the motor, according to where it's target position is.
I wonder if there is some serious confusion here seeing as the OP is a beginner.
For Arduino projects the word "servo" usually means the sort of thing that is used to move the control surfaces of model aircraft. It's often referred to as a hobby servo or an R/C servo - but mostly just as a "servo".
In the industrial machining world the word servo is also used to refer to a sophisticated and expensive device that can be used in place of a stepper motor - I would be surprised if that is what the OP has in mind.
Conceptually a hobby servo is very different from a stepper motor. Servo's are designed to move to an angle between 0 and about 180 degrees in response to a command from the Arduino. Stepper motors, on the other hand just move one step at a time very accurately (and are not restricted to 180 deg) but there is no way to tell what angle they are actually at.
There are many applications where either a servo or a stepper could be used. In general servos are cheaper and much easier to use if they are suitable for the application.
...R
Robin2:
I wonder if there is some serious confusion here seeing as the OP is a beginner.For Arduino projects the word "servo" usually means the sort of thing that is used to move the control surfaces of model aircraft. It's often referred to as a hobby servo or an R/C servo - but mostly just as a "servo".
True enough. My background led me to answer as I did. The first servo I worked on was actually hydraulic; a head positioner on a 10 megabyte disk drive, then a large variety of electrical ones after that.
Hey guys, thanks alot for answering my Q!
I was reffering to a servo as in RC/hobby style is all that I am familiar with.