Hello new here.
I am working on my new 3d printer and i came accross an interesting situation. According to the manufacture, my stepper motors need to have a voltage of roughly 0.95 volts.
I checked mine and they were 0.81 volts, hence the not so smooth prints. Ok, so i increased to the recomended specs they told me to. Now the most fasinating thing has happened and i do not know if its just me or what.
But when i power the machine on, home it to its home posistion, once the motors have stopped moving, i can hear this low volume high pitched sound like a hissing sound. I sometimes hear this same sound with other electronic devices as well, such as my wallwort for my cell phone, or my gpu in my PC. the apartment is a new complex and the power is clean and grounded.
What is this sound and should i be worried. I mean, others cant hear it but i can. Its high pitched haha
thanks

 

Even when stationary, the steppers are powered. The motors are supplied by a system to control the maximum current through the motor winding. That control is achieved by a PWM system and so the motor current isn't a steady DC but made up of high frequency square wave. What you are hearing is the result of that switching frequency.

This will be more noticeable to you if you are young. Us oldies are immune to such things!

 

I think the voltage readings you are referring to is on the current setting adjustment. The motors are not running on that voltage, it is just what the current limit circuit input is set at.
As the current is increased, the noise of the Pulse Width Modulation may be more noticeable as the current pulses are higher.
As AlbertHall mentioned above, the motors are powered, not just when they are turning, but also when they are holding a fixed position.
Just out of interest, what 3D printer did you get?
(I have 3 ).

 

As others mention, It is important that stepper motors are operated at the Rated Current value, you cannot often tell by measuring the voltage as the power supply is often much higher than the stepper rated voltage, as the drive uses this higher value in order to maintain the rated current over the RPM range.
Max.

 

Just wait until you are older -you won't be able to hear it.

It is possible that the manufacturer is not aware of this noise, particulaly if the machines are tested in a noisy location. It can happen to the best brands.

 

This will be more noticeable to you if you are young. Us oldies are immune to such things!

Just wait until you are older -you won't be able to hear it.

Translation: Us old guys are deaf! (no immunity and no special skills required)

 

Albert is right about PWM being the culprit of the sound you're hearing. The motor is being fed current by the driver, and the noise is probably being caused by the armature or coils vibrating due to not too tight manufacturing tolerances. I wouldn't worry too much about it, unless the motor starts getting way too hot (more than about 55°C) over time. Although they're supposedly capable of withstanding up to 70°C and even up to 85°C, depending on their quality.

 

I wouldn't worry too much about it, unless the motor starts getting way too hot (more than about 55°C) over time. Although they're supposedly capable of withstanding up to 70°C and even up to 85°C, depending on their quality.

And the (mean) current is the decider, important to observe the motor spec sheet for exact value.
In many cases you can resort to the natural holding torque when stationary and turn the motor off, for temp control.
Max.

 

Many years ago I could hear the 15kHz flyback frequency of the old analog TV sets, but those days are long gone (for both my ears and the TV).
Now I think I'm down to a few kHz.

 

Many years ago I could hear the 15kHz flyback frequency of the old analog TV sets, but those days are long gone (for both my ears and the TV).
Now I think I'm down to a few kHz.

I can still hear a faint high-pitch buzzing sound coming from a miniature 110VAC to USB charger ... is there a simple way (say, with a smartphone) to record an analyze it?

 

Many years ago I could hear the 15kHz flyback frequency of the old analog TV sets, but those days are long gone (for both my ears and the TV).
Now I think I'm down to a few kHz.

Same here, and the spectrum is narrowing.
In UK the old B&W H.O.T operated at 10.125Khz and 405 lines, so it was Really prominent.
Max.

 

Ha! ... I knew it! ... I downloaded an app, and as I ran the phone with its mic close to the source, I could see the 14 kHz band fluctuating up and down... the bands to the right is just background noise... a gardener is currently mowing the lawn outside ... a little annoying, btw.

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Now I'm feeling good about myself ...