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Topic: 3v motor question (Read 448 times) previous topic - next topic

jaredpi

Quick question;
what is generally the maximum voltage that can be applied to a 3 volt motor. And no, I do not know what type of motor it is or where it is from (I got it from an old toy robot I found at a yard sale).

RuggedCircuits

Is this a trick question? ;)

Generally, a 3V motor is intended to have 3V applied continuously, no more. Or, you can apply 6V 50% of the time using a technique known as pulse-width modulation (PWM). This is implemented using the Arduino analogWrite() function.

Similarly, you can apply 12V 25% of the time, 24V 12.5% of the time, etc. though once you get to about 10x the rated voltage (very roughly) you have to make sure your PWM frequency is fast enough to prevent current from going too high during the on-phase.

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jaredpi

i ask because i tried 5 volts and it worked(pretty well), and was wondering if a voltage that high would eventually damage it.

James C4S

#3
May 09, 2012, 01:29 am Last Edit: May 09, 2012, 01:38 am by James C4S Reason: 1

and was wondering if a voltage that high would eventually damage it.

Yes.

But in fairness, everything breaks eventually.
Capacitor Expert By Day, Enginerd by night.  ||  Personal Blog: www.baldengineer.com  || Electronics Tutorials for Beginners:  www.addohms.com

cr0sh


i ask because i tried 5 volts and it worked(pretty well), and was wondering if a voltage that high would eventually damage it.


It really depends on how cheaply made it is. Back when I was a kid (25+ year ago), I used to "overvolt" motors all the time, for various reasons; I ran 3 volt motors off of 12 volts for short periods of time, but most of the time I only went up to about double the "known" voltage. I did find that this generally wore out the brushes fairly quickly (being that they were nothing more than copper strips rubbing against the commutator), but generally the bearings went quicker (just the metal shaft against the plastic rear "bell" housing piece, and if you were lucky there was a sintered bronze "oilite" bushing on the output shaft end), resulting in high-pitched squealing.

These were fairly cheap motors for the time; today's small motors would likely be even cheaper; you're overvolting by about 50 percent, which is probably the limit. You'll wear it out quicker, and if you put a load on it, you -may- burn the winding out, depending on the current capability of the power supply. Higher quality motors with thicker gauge wire in the windings, ball bearings, and carbon brushes can generally be abused more, up to a certain limit. In some cases with such motors, you may find yourself demagnetising the field magnets from overheating the motor before anything else.
I will not respond to Arduino help PM's from random forum users; if you have such a question, start a new topic thread.

jaredpi


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