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Topic: Will a 5.2V supply kill a 5V stepper motor? (Read 655 times)previous topic - next topic

tyler_newcomb

May 25, 2016, 10:52 pm
Hello all.

I am trying to control a stepper motor, but I do not have a power supply. I found an AC to 5.2V DC power supply hanging around. If I use this to power the motor, will it work or will it cause damage? The supply is at 450 mA. The motor is from Adafruit, it is 28BYJ-48 5V DC.

When you answer, please don't just say yes or no, but explain how you figured that out so that I can learn. Thank you
I am not extremely knowledgeable, but I am always willing to learn!

Paul__B

#1
May 26, 2016, 12:01 am
The motor will be just fine - but it needs to be a properly regulated supply - which something specifying "5.2 V" presumably must be.

Why?

Well, the motor is a mechanical device, small variations in voltage, and thus power, are trivial.

So why does it matter more for some things?  Well, semiconductors (diodes, transistors, ICs) have a critical "breakdown" voltage at which they draw far more current than they can stand and can thus be overheated internally and burn out.  Resistive devices, such as a motor, simply draw a little more current and can even tolerate this for short periods because they have thermal mass.

Koepel

#2
May 26, 2016, 12:05 amLast Edit: May 26, 2016, 12:06 am by Koepel
As you can read on that page, they tried 9V.

A stepper motor does not really use voltage, it uses a certain current through its coils.
For large stepper motors, there are drivers that push a certain current through the coils. That is how it should be done, but for the small stepper motors the impedance of the wires is used to allow a certain voltage at the coils. The 5.2V is no problem at all for this stepper motor.

tyler_newcomb

#3
May 26, 2016, 12:24 am
The motor will be just fine - but it needs to be a properly regulated supply - which something specifying "5.2 V" presumably must be.

Why?

Well, the motor is a mechanical device, small variations in voltage, and thus power, are trivial.

So why does it matter more for some things?  Well, semiconductors (diodes, transistors, ICs) have a critical "breakdown" voltage at which they draw far more current than they can stand and can thus be overheated internally and burn out.  Resistive devices, such as a motor, simply draw a little more current and can even tolerate this for short periods because they have thermal mass.

Thank you! That perfectly answers my question.
I do have one more question though. I am using a 1A H-Bridge. If I hook up a power supply to it that is within the voltage range (4.5-36V) and has an output current of 1.5A, will that damage the H-Bridge?

Thanks
I am not extremely knowledgeable, but I am always willing to learn!

terryking228

#4
May 26, 2016, 12:42 am
Hi,
Quote
The 5.2V is no problem at all for this stepper motor.
That looks right..  See details of running that motor  HERE:

Another factor: What is the "duty cycle"??  Once a motor has reached it's destination it can be powered off and still stay in position if the physical torque applied is not too much..  So you may be able to power down the motor when it's not moving..

Regards, Terry King terry@yourduino.com  - Check great prices, devices and Arduino-related boards at http://YourDuino.com
HOW-TO: http://ArduinoInfo.Info

Archibald

#5
May 26, 2016, 04:38 am
I do have one more question though. I am using a 1A H-Bridge. If I hook up a power supply to it that is within the voltage range (4.5-36V) and has an output current of 1.5A, will that damage the H-Bridge?
As you are using a (dual) H-bridge, you will not be connecting the centre taps of the windings. The Adafruit web page states that the resistance per winding is approximately 42Ω so with 5.2V, by Ohms Law, you can expect a current of approximately 124 mA per winding (ignoring voltage drop through the H-bridge).

The resistance of both windings of my motor is 52Ω.  In the information linked by Terry, it implies that half a winding is 31Ω. There seems to be a rather wide variation in winding resistance.  Anyway you will not damage the H-bridge but be careful to avoid any accidental short-circuits.

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