Noisey MOSFET RGB LED driver problem

Other Hardware LEDs and Multiplexing
1

Hi

I'm controlling a 12v RGB LED strip from an Arduino Mega following the tutorial here

I'm controlling with 3 pots via the Mega's ADC & everything works fine or so I thought!

In addition I have 3 servo motors that are also controlled by another 3 pots these also worked well when tested without the LED driver attached. As soon as I wire up the LED driver there is a crazy amount of noise generated that feeds back into the servo control that manifests as random jittering of the servos.

I have tried putting a number of different capacitors (basically whatever I could find in the cupboard) across the 12v - ground rails. Which do seem to filter out the higher harmonics of the noise but to get the noise (and the servo jitter) to disappear I lose servo response to their control pots.

I've also tried a couple of moving average algorithms in software whilst they do have an effect they by no means filter out enough of the noise.

Any tips on how to go about resolving this besides having 2 seperate systems running?

Are there any decent off the shelf drivers that dont create loads of noise?

2

Without a full description of your arrangement we may never know! :astonished:

3

I have tried putting a number of different capacitors (basically whatever I could find in the cupboard) across the 12v - ground rails.

Without saying what values they were this is not much help.
We need details of your power supply, most beginners vastly underestimate how much power a servo will draw for very short periods.

First of all implement star wiring on the power. This is where the grounds for all the sub systems meet at one point. Same for the power.

Next instead of random capacitors use a pi decoupling arrangement with an inductor, it is the last circuit here:-
http://www.thebox.myzen.co.uk/Tutorial/De-coupling.html

If you can't decouple it properly then an easy solution is to have a separate power supply for your servos and lights.