Best method for powering 6x servo motor Arduino robotic arm

I need to power a 6x servo motor robotic arm that will be controlled via an arduino uno.
This is the robotic arm:

The arm has 2x mg90s servo motors and 4x ks3518 servo motors.

Each servo motor will require 1-2A of current (2 to be safe). Therefore, A power supply that can power all 6 motors will need to provide a draw of 12A.

I am wondering if I should purchase 6x 5V (2A) power supplies, one for each servo motor, such as this:

Or could I use a 5V (26A) switching power supply, such as this?

In theory, using this switching power supply, would I be able to power a second identical robot (i.e another 6 motors) by having one robot powered by one set of the power supply’s V+ and V- terminals, and the other robot being powered by the 2nd V+ and V- terminals on the same power supply?

This project is for an art installation and I would eventually like to use up to 10 robotic arms in a exhibition context (i.e being active for 8 hours a day). I would appreciate any input from people who might know the best way to go about this to ensure the most reliable method of powering the servos. Does anyone have experience in powering 6x axis robotic arms without a consumable battery ?


Hi Sam,

You’re on the right track. Probably easiest to go for the larger supply and run a single +5v bus. Just note that high current supplies may float at a higher voltage and have a minimum load requirement to bring them down to their rated output.

If this is the case it’ll say so in the datasheet.

Also, definitely a good idea to start out small. Robotic arms (aka kinematic chains) are very complex things. Every extra joint makes them exponentially more complex.

Hi Sam
Yes you should be able to use both power supply outputs. They will be connected together internally anyway. Maybe via diode from same source. The unit does not have 2 separate power supplies. Be aware though the 130 Watts quoted is the TOTAL capability. I don’t think output loads have to be balanced as long as you stay within a total load of 130 Watts.
Oliver mentions the output voltage floating high. MeanWell are a pretty good unit and I think the voltage will be OK over a wide load range. In the old days switch mode supplies needed a minimum load to even start up. I think those days are long gone.
I am not totally conversant with servos and don’t know what the position holding current would be. If it is only a relatively small percentage of the moving current the only time you need anything like 12 Amps (7.2A) would be when all 6 servos are moving at once. Only you know how often that would be.
You will need to use an adequate wire size between your Power supply and the distribution point for your servos or you may have a problem with voltage drops. Your final set up will dictate this.
Cheers Bob

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I See, I also think I should use some kind of capacitor to smooth over the spikes in voltage. Any ideas on what kind of capacitor I should use? and how to use one in an arduino uno & breadboard circuit?


You’re thinking of a decoupling capacitor. Just for power supply stabilization a big fat electrolytic cap is fine. Mind you there’s plenty of juice available from that meanwell supply already. I doubt you’ll need them for this tbh.

Hi Sam
Where do you expect these spikes. The output of the power supply should be clean and should not require any conditioning. You certainly don’t want capacitors across servo control signals as if you distort them too much the servos will quit.
Not a good idea to just throw capacitors around willy nilly anyway because given the right conditions you can get some very interesting and usually unwanted results.
Cheers Bob

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