Hi,
I'm using the Arduino 5V dc output to power load cell from which I then read the signal. I need the power supply to the load cell to be as stable/smooth as possible. Right now, when I power the load cell with the Arduino, the output I get is more noisy than when I power them with a power supply.
I was suggested using capacitors to smooth out the 5v power supply, but I can't find an Arduino example, does anyone know where I could find a sample circuit?
Thanks! 
Load cell? You're trying to charge a cell directly from an arduino pin?
A load cell is a beam with a strain gauge soldered on top. Basically think about it as resistances that change values depending on the load. So I give it 5V and ground as input, and I measure some output voltage that depends on the load. The output is amplified by instrumentational amplifier. The problem is the signal is small, and if the 5V that I use for to power the OPAMP and and strain gauge input is not smooth, my output will be extremely noisy.
Would a simple capacitor in parallel do the trick? Should I use 2 inductors to replicate the voltage onto another circuit and then put it in paralllel with the capacitor? But how do you do that in practice since the inductors come with shielding??
Is there a simple common way to smooth out the 5V DC signal from ripples?
You might try powering the load cell from the arduino 3.3vdc pin and see if that gives you a quieter measurement signal. You can 'fix' the scaling problem/difference in your sketch software if the signal is otherwise less noisy running on 3.3vdc. Worth a quick experiment.
Do you have a schematic for the instrumentation amplifier circuit ? I need one for a project I'm working on.
Do you have any electrolytic caps (100uF) accross your +5V dc to absorb the ripple ?