I'm working on a project where I'm driving three separate motors via relays controlled by an Arduino Uno. I have the motors supplied by a 12v x 1amp wall wort. The Arduino is also powered via this wall wort connected to its Vin pin. When running more than one motor, from time to time the Arduino will reset back to the beginning of the program. Originally, I thought that the motors were drawing too much current and causing the supply to trip out. But, I've upped the supply to a 1.5A unit and the problem still happens when the motors don't have any load. Also, if I power the Arduino from a separate power supply (i.e. USB) this problem goes away.
From searching the forums, I think I found the answer. I think that when two motors are running at the same time, they produce enough noise at the Vin pin to reset the Arduino. I've read about people fixing this by placing 220uf capacitors between the board and the power supply. But, I'm not too familiar with capacitors and how this part of the circuit looks. If I put the capacitor in-line with the 12v I have coming to the Vin, nothing seems to get power. How would I hook up a capacitor to my Vin line to filter out some noise?
Thanks for any help!