RGB Led strip pot control burned my arduino? I made this exact build on my Arduino, with the following differences:


I'm using Arduino Nano
Transistors I use are 2N2222A
I'm running everything on 12V except Arduino, I use LM317 to feed Arduino 6v


Here's the build:


Here's what happened. First, it started to get strange voltage, arduino would light up even when disconnected from power. After that, Arduino kind of got fried, when I connect it to USB, nothing happens. I can give it 6v to VIN and ground it with the rest, but turning potentiometers only dims the onboard LED of the Arduino and that's it.

Now I'm going to go and pick up a new nano, however, I'd prefer not to fry that one, so figuring out why this one burned would be nice.

PS. The image shows RGB LED instead of RGB LED Strip because 123d doesn't have strip component.
First, as Majenko said, you need resistors between the arduino output pins and the transistor bases. Start at something like 330 Ohm.
Second, what is the value of the potentiometers? If it is too low you would be drawing too much current from the 5V pin to the ground.
Third, you should power the arduino with at least 7V, assuming you power it through the Vin pin or the power jack. 6V is considered too low.
I assume the pins connected to the potentiometers are initialised as inputs. Otherwise, it would be possible to burn your arduino by having them source/sink too much current (i.e. by turning the potentiometers to one end or the other).