however the Arduino can't supply that kind of current. You will need a seperate voltage supply. One motor can draw up to 430mA. Multiply that by 4 or 5 and that is a lot of current.
Also the motors will probably be pretty noisy, so it would be better to seperate the motors' and Arduino power supplies.
Admittedly, I am very new to these things so I might have a misunderstanding, but based on what I've read I was under the impression that one of the functions of a transistor is to allow a high-power device (like a DC motor) to be able to safely draw more current from a relatively low-power device (like the Arduino). Or am I confusing things?
There's a couple of Application Bulletins on the site of your motor supplier that help explain (essentially what everyone else above has mentioned - the current and back EMF can damage your arduino):See driving motors with PWM section here:http://www.precisionmicrodrives.com/application-notes-technical-guides/application-bulletins/ab-012-driving-vibration-motors-with-pwm
Thanks for the link! I apologize if this is a naive question, but if I use separate power supplies for the Arduino and the motors, will that not be enough to prevent issues with noise and back EMF?