How to control computer fans with Arduino UNO + vvvv (Firmata)

vvvv beta question
8

you are on the right track, but i think you will burn out your arduino doing this…

i will back up what soriak said… but i would do this in 2 stages for the sake of learning.

start by powering the arduino normally, then take 5v from the arduino to power the breadboard (with transistor, ONE motor, and you will prob need a resistor somewhere to be safe, prob a back-current doide aswell, but thats getting ahead of ourselves)
…and then complete the power by returning from the breadboard to the ground on the arduino.
get that working, then move on…

then try with more motors. for this i would run a seperate power supply for the motors, as you will draw too much current through the arduino and blow it up.
…so, keep the arduino powered normally and swap the 5V for a seperate supply. then keep the ground wire from the breadboard to the arduino AND also connect the breadboard ground to your 2nd power supply. this keeps a common ground between the two which is wierd, but makes sense later. (took me ages to understand that one…)

https://itp.nyu.edu/physcomp/labs/motors-and-transistors/dc-motor-control-using-an-h-bridge/
http://playground.arduino.cc/Main/DCMotorControl
http://www.apcc.tk/diy-projects/pwm-arduino

http://luckylarry.co.uk/arduino-projects/arduino-control-a-dc-motor-with-potentiometer-and-multiple-power-supplies/

[ disclaimer - i am not an expert, just trying to pass on wot i learnt this summer ]( disclaimer - i am not an expert, just trying to pass on wot i learnt this summer )
…i would draw you a diagram, but have to go to sleep, sorry