Hi, guys! I am having trouble with powering 12V RGB strip and an arduino controller via the same 12V 5A power source. I am using 3 TIP31C transistors (1 for each channel). I connected the power source + to the + of the LED strip, the arduino and the strip share GRD. I also did connected a wire from the power source + directly to the VIN of the arduino. All works fine .. for a few seconds. After that it seems like the Arduino restarts on its own, so my LED strip starts to go on and off rapidly. I did the same project, using the same components and same wiring once a few months ago. I don't have any problems with that project (I also have a HC-05 module hooked up to the arduino, so I can change colors via an APP). I thought that this controller was maybe damaged, so I tried with another one ... the problem was still there. Finally I powered the arduino via a different (9v 1a) power supply. Now all is working as it should, but I am still wondering why did the same wiring worked for my first project. Did any body had the same issue before?
What you say you did sounds reasonable, however it is often the case that you missed something. So a schematic and photograph would be a good start.
It could be your power supply, did you have a large capacitor across it?
Did you use solderless bread board? It is not good at handling large currents. How long is your LED strip and what current is it taking?
A TIP31 is a bad choice.
It needs a base current of 1/10 of the collector current for saturation.
Something an Arduino pin can't provide.
A darlington, like the TIP120, would be better.
Logic level mosfets would be the best choice.
What value base current limiting resistor are you using now.
The Arduino shutting down with >9volt on V-in suggest you didn't use base resistors.
Leo..