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Author Topic: High Pitched noise from motor at low revs  (Read 6865 times)

Andy K

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High Pitched noise from motor at low revs
« on: April 05, 2007, 08:01:40 pm »

I have two boats using Mtronics speed controllers, one is a 15 Amp controller running a Graupner 600 motor on 6v. The other is a 25 Amp controller running a Pitman motor on 12v. I have noticed that at low revs both boats generate high pitched noise, from the motors, that goes as the throttle is opened. I presume that this is something to do with the way the speedcontrollers work. Does anyone know who I can reduce this noise.
Thanks
Andy
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Faraday's Cage

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Re: High Pitched noise from motor at low revs
« Reply #1 on: April 05, 2007, 08:30:24 pm »

Hi Andy,

Just to confirm your suspicisions, I have same controller on 2 x 385 motors with same effect.

Dont know if there is a solution to the noise problem.  :o

Terry.
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Andy K

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Re: High Pitched noise from motor at low revs
« Reply #2 on: April 05, 2007, 08:45:33 pm »

Glad to here someone else has the problem. I thought I would ask the question on the forum just to see if anyone had any answers before I try Mtroniks.
Thanks for letting me know
Andy
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ministeve

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Re: High Pitched noise from motor at low revs
« Reply #3 on: April 05, 2007, 09:06:50 pm »

hi that is the sound that your motor makes from being switched on and off many times a millisecond with no length to the pulse it is very normal of speed controllers of this sort
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DickyD

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Re: High Pitched noise from motor at low revs
« Reply #4 on: April 05, 2007, 09:19:31 pm »

I must be lucky.
I have a Deans Marine and an Overlander ESC and no noise.

Richard ;)
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Andy K

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Re: High Pitched noise from motor at low revs
« Reply #5 on: April 05, 2007, 10:10:20 pm »

Thanks for the explanation ministeve, any idaes as to how I can stop the noise.
Andy
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Colin Bishop

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Re: High Pitched noise from motor at low revs
« Reply #6 on: April 05, 2007, 10:18:48 pm »

Earplugs?
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Andy K

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Re: High Pitched noise from motor at low revs
« Reply #7 on: April 05, 2007, 10:31:20 pm »

I can see why you are an Admiral steve.
Andy
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Andy K

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Re: High Pitched noise from motor at low revs
« Reply #8 on: April 05, 2007, 10:31:57 pm »

Whoops that should be Colin.
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kendalboatsman

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Re: High Pitched noise from motor at low revs
« Reply #9 on: April 05, 2007, 10:41:52 pm »

Hi Andy,

Adjusting the transmitter throttle trim 1 or 2 notches can often adjust the speed control frequency enough to remove or reduce the feedback whine you are experiencing. Will ask at work tomorrow as I am an electric motor fitter/winder by trade. On the older ESC models you could adjust the pots to trim the frequency but the modern one touch ESC doesn't have that facility.

Clive :)
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Colin Bishop

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Re: High Pitched noise from motor at low revs
« Reply #10 on: April 05, 2007, 11:04:29 pm »

Sorry about the joke! Actually I have one that does something similar. At centre off it is silent but as soon as you move the throttle there is a pronounced whine which dies away as the motor actually starts turning. I thought it was just something to do with the design.
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FullLeatherJacket

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Re: High Pitched noise from motor at low revs
« Reply #11 on: April 05, 2007, 11:33:53 pm »

I had this same thing with ACTion ESCs when Craig changed them from 50Hz to 3000Hz signal pulses. It was so b100dy irritating that I went back to the old style ones I'd used before. The lower frequency ones also make a noise at very low revs but, at 50 Hz, it's more of a growl than a squeal. I think one of the top-end Electronize jobs has a switchable frequency if the noise gets too bad for you with the MTroniks ones.

Suit yourself, eh?  ;)
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Andy K

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Re: High Pitched noise from motor at low revs
« Reply #12 on: April 06, 2007, 03:00:41 am »

Thanks for the input everyone, I think I will email Mtroniks and see what they have to say.
I will post the response if I get one.
Andy :D
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chromedome

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Re: High Pitched noise from motor at low revs
« Reply #13 on: April 06, 2007, 11:22:35 am »

I like as much noise as you like from a motor.More realistic?I even try to mechanically generate engine noise by by the attachment  of little arms to  appropriate rotating parts of the prop shaft...nothing that will increase the ampage though.I just find it fun experimenting.

  chromedome
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FullLeatherJacket

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Re: High Pitched noise from motor at low revs
« Reply #14 on: April 06, 2007, 11:32:01 am »

I like as much noise as you like from a motor.More realistic?I even try to mechanically generate engine noise by by the attachment  of little arms to  appropriate rotating parts of the prop shaft...nothing that will increase the ampage though.I just find it fun experimenting.

  chromedome

You can't have heard the awful shriek these things make. As for "realistic", I've never heard a marine diesel sound like a dog-whistle before. I have no problems with noisy gearboxes etc - shows me the thing is still alive, but a motor that sounds like Bjork duetting with Kate Bush doesn't do it for me!!

Experiment away, old thing - it's a free country!  ;)

FLJ
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Stavros

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Re: High Pitched noise from motor at low revs
« Reply #15 on: April 07, 2007, 11:25:31 pm »

Andy k I will be interested in your findings cos guess what same esc same high pitched noise !!!stavros
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ukengineman

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Re: High Pitched noise from motor at low revs
« Reply #16 on: April 08, 2007, 03:17:43 pm »

Some of the Electronize ESC's can be set by a switch to high or low frequency switching. There is also an auto position which automatically selects low frequency at low power and high frequency (more efficient) at high power. I use mine in the auto mode.
Alan
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Stavros

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Re: High Pitched noise from motor at low revs
« Reply #17 on: April 08, 2007, 05:05:14 pm »

Welll now htere is no noise as cspeed controller decided to burn it's self out!!!!!!!of course in hte middle of the b..... lake!!!!!! so I think it's sod the Electronise and go Mtronics Stavros
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DickyD

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Re: High Pitched noise from motor at low revs
« Reply #18 on: April 08, 2007, 06:02:20 pm »

Try the overlander esc from Westbournes plug it in and go. No noise not complicated.

Richard
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Re: High Pitched noise from motor at low revs
« Reply #19 on: April 08, 2007, 06:48:20 pm »

Quote
I have two boats using Mtronics speed controllers, one is a 15 Amp controller running a Graupner 600 motor on 6v. The other is a 25 Amp controller running a Pitman motor on 12v. I have noticed that at low revs both boats generate high pitched noise, from the motors, that goes as the throttle is opened. I presume that this is something to do with the way the speedcontrollers work. Does anyone know how I can reduce this noise.
Thanks
Andy

As ministeve said, the noise is caused by the motor being switched on and off many times a second, the faster the frequency the less noisy the motor.

To reduce the noise it is possible to add a capacitor onto the motor terminals to provide a more constant supply. This reduces the abruptness of the on/off signals and therefore quietens the motor. ;D ;D ;D

Andy K

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Re: High Pitched noise from motor at low revs
« Reply #20 on: April 09, 2007, 08:58:09 am »

Thanks for the idea Fireboat the only thing is that I already have 3 capacitors on the motor contacts. Negative to motor body, positive to motor body and between negative and positive. I am going to try 2 x 100 microHenry chokes on the supply leads to see if this has any effect. I will keep you posted
Andy K
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Re: High Pitched noise from motor at low revs
« Reply #21 on: April 09, 2007, 10:14:27 am »

I see what you mean about the capacitors, ha ha it can get a little ridicules. Technically speaking the chokes should work OK, but I've never tried this method so do keep me informed. ;)

wombat

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Re: High Pitched noise from motor at low revs
« Reply #22 on: April 09, 2007, 11:48:54 am »

The width of the pulses will deterimine what bandwith of filter you need. However, putting in such a filter will affect the performance of the system. You may find that by flattening out the pulses to get the noise down, you widen out the deadband. Also be aware that the energy absorbed has to go somewhere and rate the filter accordingly.

The noise IIUC is caused by the pulsing of the armature of the motor because it can rock but there is not enough torque generated to spin the armature past the next commutator element. You could try reducing the backlash in the mechanics and use the prop and water t odamp it out. Or you could live with it - careful setup of the neutral so the motors shut up at nutral and always run past the deadband. Minimise the mechanical load to minimise the deadband - that sort of thing.

Wom
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Andy K

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Re: High Pitched noise from motor at low revs
« Reply #23 on: April 10, 2007, 05:24:45 pm »

Here is the reply from Mtroniks

The reason for this noise is a combination of the speed controller and the motor you are running.
The noise is due to the frequency of operation of the ESC, this noise cannot be stopped but ....
different motors will cause the noise to vary in loudness and pitch.

Regards,
Paul
Mtroniks Ltd.
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