Servo motor: power supply from Arduino vs external power supply

Using Arduino Motors, Mechanics, Power and CNC
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Hi.. I would like to know what are differences if I use external power supply for powering servo motor instead power supply directly from Arduino? Is it possible to damage Arduino?

Thanks for all of your answers in advance!

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Lotsopa:
Hi.. I would like to know what are differences if I use external power supply for powering servo motor instead power supply directly from Arduino? Is it possible to damage Arduino?

Maybe not damage your Arduino, but cause unwanted board resets, low voltage excursions, USB thermo fuse to open up tuning off the board. Best to always use an external DC power source for powering servos, and I would suggest a 1 amp rating for each servo you wish to power.

Lefty

Thanks for all of your answers in advance!

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You should probably connect an external power supply to run the servos if you are planning on using it for an actual project.
You can safely power ONE SMALL servo off the arduino 5v source.
Don't try to go anywhere above that, because it will cause excess heat on the power regulator.
I just learned all of this, so correct me if I'm wrong.

Here is my very recent thread asking on how the wiring should be for external power:
http://arduino.cc/forum/index.php/topic,91870.0.html

Here is the external power regulator that I'm using (it's a bit expensive because it is adjustable from 3v to 8v output):
http://www.dimensionengineering.com/DE-SWADJ3.htm

Here is a 5v switching regulator that does 7A (i was planning on getting this one, but i needed my servos to run at full power for lots of torque):

Also, always use switching regulators for high power applications, because unlike linear regulator, switching regulators do not dissipate much heat and are highly efficient at high loads.

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tincanman:
You can safely power ONE SMALL servo off the arduino 5v source.

This should be read as "one small servo with -NO LOAD-"; unless you know the current needs of the servo under load and/or at stall, you should only run it off the Arduino's regulator without any load attached (ie - nothing connected to the servo horn).

Also - as retrolefty mentioned, budget 1 amp per servo you need to control - so if you have 8 servos to control, figure on a supply that can source 8 amps.

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cr0sh:

tincanman:
You can safely power ONE SMALL servo off the arduino 5v source.

This should be read as "one small servo with -NO LOAD-"; unless you know the current needs of the servo under load and/or at stall, you should only run it off the Arduino's regulator without any load attached (ie - nothing connected to the servo horn).

Also - as retrolefty mentioned, budget 1 amp per servo you need to control - so if you have 8 servos to control, figure on a supply that can source 8 amps.

Yes, that is entirely correct. I should've probably mentioned that. It is ok if you have no load and is just testing to see if the servo works.

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A diode can be used on the ground pin of a 7805 voltage regulator to up the output voltage to ~5.7v for much better servo performance.

1 Like
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Hey sir please can you help by giving the circuit diagram for my 4 servos ! I would be thankful
My email : marwa.boukech@gmail.com

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