Simple electromagnet

Hello - I have a simple application that I am looking at, trying to turn a series of small electromagnets on in sequence (not very fast). The intent is to pull an object along a track. Any suggestions on:

  1. Where I can buy small electromagnets?
  2. How do I interface them with the Arduino? Do I need to use a controller of some kind to provide the necessary current voltage? How many electromagnets can I control with one Arduino board? I would like to control 6 electromagnets.
  3. Are there any products out there that interface directly with the Arduino? One I have found is the Grove electromagnet.
    Is there anything on the sparkfun site that is similar?
    Thanks for any suggestions.
  1. Don't know. Can wind your own, iron nail and magnet wire.2
  2. Use a transistor to control current going thru the magnet wire. Use the 6 PWM pins, 3,5,6,9,10,11, so you can control the amount of magnetism with analogWrite( ).
    You also create PWM in software, so I would say 20 magnets without resorting to additional external logic.
  3. Transistors interface directly with Arduino. AOI510 has very low on-resistance (Rds).
    Q1 on the Grove electromagnet does the same.

Be careful with electromagnets around your hard drive.
I don't get any hits for electromagnet products at sparkfun,com