External Powering of Servos

I recently came across a problem with my current project: lack of power. Simply put, ever since I began using MegaServo, I have been unable to control 12 servos on an Arduino because the 5V power supply isn't enough to power them all. Would it work to connect them all to en external power and ground, assuming I grounded the Arduino to that same ground?
I tried this out with one servo and it worked splendidly, just curious if it would work with twelve. To clarify, I am still using the Arduino to control the servos through the signal wire.
The other problem I have is that I am using hobby servos (Futaba S3003) in my project, which are only rated for 6V each. However, I have several variable power supplies (4.5-9V, .5 A), as well as a 12V 10A power supply. I think it would be certain death to hook up just one of the servos to the 12V supply, but would they survive if I used that power supply for all twelve? If not, what type of power supply would you suggest? I know this isn't technically an Arduino question, but I figure all the brilliant servo folks hang out around this forum as well (:

Make a simple 5V supply using such as the one shown here:


or this:

It is similar to what is used in the Arduino. I am not sure whether it will handle high currents though.

Thank you for the help, but my main problem is that I cannot run all 12 servos off of a 5V power supply ):

The power supply in that second link will not be enough to power 12 servos. You will need something that can supply at least a few amps. How much exactly depends on your servos and the load you put on them.

BTW, the playground page for MegaServo does say you can use (and probably will need) an external power supply for twelve servos.

edit: I did not see your previous post when I composed this. Why can't you use an external 5 volt power supply?

I have a couple 5V external power supplies, but they're only rated at about .5A and 2.5 A. Will that be enough? I also have a 12V 10A power supply, but I suspect that would cause an electrical fire, haha.

As far as the loads on the servos, some are very minimal, but others require 44 oz-in of torque (nearly the servo's maximum)

I would guess you will need more current, but try the 2.5 amp supply, it may be enough. If you have a multimeter that can measure current, you may want to check much the servos draw.

You should almost always use an a separate power supply for servos. Servos are DC motors which generate surges & noise - very bad for microcontrollers :frowning:

I'm not familiar with "megaservo", but most servos support higher voltages than 5v. Servo performance will improve at its max voltage rating. The supply does not need to be highly regulated.

A common arrangement is to feed the unregulated supply to the servos and also tap it the the 5v regulator.

Hi Joe, MegaServo is an Arduino Servo library Arduino Playground - MegaServo
the OP has a 2.5 amp external power supply but this may not be enough for all twelve of his servos

I have an S3003, and hooked it up to my bench supply at 5V. It drew about 200mA spinning unloaded, and about 400mA when I tweaked it fairly hard (probably close to its rated torque).

Depending on how many you'll have turning at once, you could probably get by with two of the 5V 2.5A supplies.

It should be better to feed them with 6V if you can, though, because you'll get more torque/mA, so the motors won't be working as hard. But make sure it's regulated: unregulated wall warts can put out much higher voltages than their nominal rating.


Thanks a million, guys, especially Mem, this is my third question you've answered (:

I'll be trying that tomorrow morning.

Yeah, like everyone else has been saying, it depends on how much current your servos draw. If you went with a simple 5V power supply based on a 7805, you might need multiple supplies since most 7805 ICs can only source 0.5-1.5 amps. It's always good to derate the voltage regulators too. Depending on what voltage you have coming in to your 7805s and how much current you draw, you'll probably need some heatsinks too. If you want more info from me, feel free to PM.

If you need high current on the +5V, you can convert ATX power supply for this test setup. It can supply more then 25 Amps. for 300W supply.
Here si the link with some pictures.