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Topic: How to switch my arduino from 3v to 5v ? (Read 3484 times) previous topic - next topic


lefty, thanks for correcting me on the usb/jack/regulator connections.


Dec 11, 2009, 04:49 pm Last Edit: Dec 11, 2009, 04:52 pm by mem Reason: 1
I think a number of people happily running projects using a hobby  servo powered from the 5v pin may be wondering if they need to rewire their servo.
I really don't think that is necessary.

I agree with Lefty that the issue does not relate to damage or safety. I believe it's a question of whether there is sufficient power available to drive your servo.

I remain of the view that although its best to use an external power source to power servos, if your servo works on the Arduino 5v line then you do not need to worry.


Dec 11, 2009, 05:05 pm Last Edit: Dec 11, 2009, 05:06 pm by retrolefty Reason: 1
I remain of the view that although its best to use an external power source to power servos, if your servo works on the Arduino 5v line then you do not need to worry.

Yes, I don't disagree with that statement at all.

However we do field questions here a lot of problems with boards resetting and other weird symptoms when using servos that usually trace back to trying to power servo(s) from the Arduino's +5vdc pin. If it works then fine, but it's bound to cause difficulties for many who are still just trying to learn the basics of using an Arduino with servos.



Dec 11, 2009, 05:17 pm Last Edit: Dec 11, 2009, 05:17 pm by halley Reason: 1
the issue does not relate to damage or safety

This is a great conversation and I know I'm taking it to the limit.  I am sorry if I sound over-zealous, but in some applications, "a servo might not work" is indeed an issue of damage and safety.  That's my point about engineering limits.

If your security camera unexpectedly stops panning, or your Halloween skeleton jaw stops waggling, you just drag it all back into the basement to tinker on it some more.

A model airplane or helicopter may work perfectly on the bench, but not when faced with higher torque under aerodynamic loads, due to limited power available.  An airframe with marginal control is dangerous to property, bystanders and the pilot.


Dec 11, 2009, 05:19 pm Last Edit: Dec 11, 2009, 05:21 pm by mem Reason: 1
Most problems people have with servos are due to power - although top of the list is forgetting to connect the grounds when using external power.

Advising people to power their servos adequately is good advice, as is suggesting the use of an external power source.  But I see no technical or practical basis for saying that a servo should  never be powered from the 5v rail.


thnx for the replies,

Unfortunately i still cant run anything from the 5v pin, despite doing everything in this thread.

I've decided to get a cheap bench top variable lab power supply to power my servos, as well as a new arduino & the motor shield from ladyada's site, just in case my arduino's faulty

I've decided to get a variable power supply as all the voltage ratings seem to be different for different servo's.

I was wondering can i run the bench lab power supply directly into a breadboard, without needing a special circuit or something to run it through?

The bench top power supply is from here




You can wire up the breadboard as in this picture: http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1250070061/6#6

Replace the battery power leads with those from the powersupply.

Don't forget to connect the grounds.

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