1. This sounds like a great project for a small servo, which would be low power draw, allow simple 1* increments (in both directions), and be controlled with 1 Arduino pin. If you need more than 180* of rotation, look for a continuous rotation servo. Do a little research on servos, but don't worry too much about getting "the wrong one". They are easy to use, cheaper than a stepper, and almost universally practical.

2. For beginner Arduino use, the Uno is a great platform and it has the USB interface you are looking for.

3. You can use a program called Processing to write a user interface to switch between different "programs" or use a mechanical switch to cycle through modes inside your code. Use of a random() function is possible inside the Arduino platform, also.

4. Connecting the knobs is a classic mechanical issue, one I've dealt with too many times. I'd reccomend a tiny elastic belt system, although a toothed connection may be just as simple for your application.

I just looked up servo motors, and they don't appear to do tiny micro movements for exact positioning, and not being able to turn 360* would definately be an issue, so I think a stepper motor would work best, from what I've seen and read on the internet so far about motors.

I found this video which shows a stepper motor making micro movements

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RE: Small Arduino USB Stepper Motor - Need Help

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Which of these motors should I get?

https://www.sparkfun.com/categories/178/

There are four stepper motors on that page and I don't know what is different about them!

Hi Jason,

No, it refers to the wiring of the coils - with a center breakout, it is possible to simplify the drive for unipolar wound motors, but with reduced torque.

Both types of motors can rotate in either direction.

I took another look at the four stepper motors, and I'm thinking the one with 400 steps/rev and only needs 3V would be the best for accuracy and low voltage.

Stepper Motor - 68 oz.in (400 steps/rev)

https://www.sparkfun.com/products/10846

but it is a bipolar motor so I need a driver. Right?

EasyDriver Stepper Motor Driver

https://www.sparkfun.com/products/10267

for the board, the unio sound good?

Arduino Uno - R3

https://www.sparkfun.com/products/11021

and the unio requires this software........

http://arduino.cc/en/Main/Software

Would this be the correct USB Cable?

https://www.sparkfun.com/products/513

and will this casing work for both the UNO and Driver or just the UNO?

http://www.robotshop.com/productinfo.aspx?pc=RB-Ard-16&lang=en-US

I would like to jump in again before you go with the stepper motor. I really reccomend going with this continuous rotation servo. It will give you 360steps/rev (because you can set it in 1* increments) and can simply be plugged into the Uno without any seperate driver. The voltage lines up nicely with the 5V output on the Uno, also. 

Will the software and program for the stepper motor also work with the servo?

The servo is about the same price as the stepper, so I could get both and compare the two in performance!

My main concern though is that a servo is not made to make micro movements and a stepper is, so if 400 stopping points are important, then why would a servo be better? Can a servo stop at 400 different stopping points like a stepper?

The software is good for any arduino project you can think of (from motor control to home automation to GPS navigation), the difference is in the code you write. As far as accuracy is concerned, a continuous rotation servo can be turned (and held) to any degree value. That means it has 360 steps/rev. That's barely less than the 400 steps/rev you are looking at in the stepper.

Is it confirmed that the product referred above can be rotated to a defined position? As I understand, it appears to be a pre-modified hobby servo which uses PWM to control speed (not position). (Some of the comments on that page also seem to state this, but I have not used the product so I can't say for sure). The modification entails removing the internal potentiometer, so that there is no longer any feedback on position.

i find www.sparkfun.com to be over priced, you can find the same items on ebay for a lot cheaper, and if you are new with arduino its better to buy a clone of it which you can find on ebay for around US$ 10 and it works exactly the same  the real arduino uno r3 is for US$ 29 its 3 times the price  and since i am a beginner i dont want to buy the the real one just for a few stickers that come with it  then endup burning the board by making a few wrong connections 

Good luck then with getting support from the vendor.

At least with most of the 'non ebay' suppliers, you get supporting information.

Element14 has very competitive pricing, along with support   ...even this forum.

When you buys a genuine UNO, you get far more than 'just a few stickers'.

Mark

Jason C,

     I'm going to back up a bit in response to Shabaz's post. I misunderstood the product that I posted for you. You can still make it stop at any given degree, but it would not be nearly as simple as I made it sound originally. You should still consider the servo idea, but your stepper motor might be easier than the continuous rotation servo. Hope I haven't hurt your project too much.

i prefer finding the cheapest way of doing very thing because i am a student have no sorce of income, just the pocket money i get. and doing this i feel i am getting a little more knowledge on the components and learn more since i have to do a little more research because of the lack of support given by cheap item sellers. my last option i cry on element14  and some well experienced people like you help me out

it makes me happy if i am able to do the same task using less money

i do love the work arduino is doing and i will support the company by buying their products when i have my sorce of income 

according to me 28BYJ- 48 5V stepper motor can be useful in projects where less torque is required, its very easy to use and very cheap

i prefer finding the cheapest way of doing very thing because i am a student have no sorce of income, just the pocket money i get. and doing this i feel i am getting a little more knowledge on the components and learn more since i have to do a little more research because of the lack of support given by cheap item sellers. my last option i cry on element14  and some well experienced people like you help me out

it makes me happy if i am able to do the same task using less money

i do love the work arduino is doing and i will support the company by buying their products when i have my sorce of income 

according to me 28BYJ- 48 5V stepper motor can be useful in projects where less torque is required, its very easy to use and very cheap