"eeeeeee" sound when using PF train motors

[toxicbananna]

Just wondering why when we use PF train motors, there will be "eeeeeeeee" sound at low speed? Any electronics expert knows??

[jtlan]

It's making that sound due to the Pulse Width Modulation (PWM) used to control the motors. Essentially, to run the motor at a lower power the receiver switches power to it on and off very quickly, but the pulsing produces an audible sound because the switching frequency is in the range of human hearing.

[Duq]

Many real life trains in the Netherlands have similar motor control and as a result make the same sound.

[Brickviller]

Many real life trains in the Netherlands have similar motor control and as a result make the same sound.

As a fellow Dutchman who travels by train, I can confirm this. I always found the sound of some trains here a little to similar to the Lego sound. Glad that question has been answered

You can hear the sound in this vid (at least if it uses that PWM stuff)

Edited June 8, 2014 by Brickviller

[LEGO Train 12 Volts]

This sound is amazing!

Thanks for this topic!

[Zerobricks]

This sound is amazing!

Thanks for this topic!

I raise you by:

[Heppeng]

Then there's our networkers which try to do racing car impressions...

[Redimus]

Many real life trains in the Netherlands have similar motor control and as a result make the same sound.

Aye, a lot of electric trains in the UK make a very similar sound to the PF motor too. It's one of the things that really impressed me about the design, it effectively provides it's own sound effects (for electric trains at least)!

Lego is also the only small(ish) modeling medium where a complex enough set of steam loco running gear makes actual clanking noises.

[toxicbananna]

whoa thanks guys, after reading up I finally understand that the sounds actually are from all motors(including 9V). initially i thought only PF train motors produce such sounds.

[1974]

While the sound comes from the motor, it's NOT the motor that's generating it. So, if you hear a standard 9V motor making that sound it's because it's controlled by PF. A standard 9V motor on metal tracks is controlled by a non-PWM (linear) regulator and does not whine. Nor does 4,5V/12V (both grey and blue) when used with they apropriate controller

Cheers,

Ole

[toxicbananna]

While the sound comes from the motor, it's NOT the motor that's generating it. So, if you hear a standard 9V motor making that sound it's because it's controlled by PF. A standard 9V motor on metal tracks is controlled by a non-PWM (linear) regulator and does not whine. Nor does 4,5V/12V (both grey and blue) when used with they apropriate controller

Cheers,

Ole

Yup that is exactly what I meant, when while playing with just the standard 9v controller, the motor does not whine at all. But if I connect PF system together with the 9V controller (as i would want to PF system to control the voltage on the 9v tracks), I did notice the sound from my 9v motors, thus this topic was created. :)

Cheers

[AlmightyArjen]

The German ICE sounds the best I think, from 1:10:

[jrathfon]

Interestingly my Prius makes the same sounds when rolling slow (say through a parking garage) in "EV" (Electric Vehicle) Mode.

[grymg]

The electronic speed controllers on R/C cars make the same exact sound as well.

[AlmightyArjen]

Every electic motor has its own most effective PWM frequency, but it is most of the times around 3kHz to 5kHz. THe sound you hear is that frequency, produced by the coils in the motor resonating at that frequency.

[Hrw-Amen]

Interesting, so LEGO trains actually sound authentic!!

[1974]

Every electic motor has its own most effective PWM frequency, but it is most of the times around 3kHz to 5kHz. THe sound you hear is that frequency, produced by the coils in the motor resonating at that frequency.

Yes, it's not the PWM freq that is much higher than this (above our hearing range)

My Tamiya RC car actually uses it's motor (when it's NOT running) as a 'loudspeaker' / soundtransducer giving a beeping signal when there's no contact to the remote control. Pretty neat

Interesting, so LEGO trains actually sound authentic!!

I still miss the deep roar from a 40L 16 cylinders combustion engine (yes there' PWM too in those trains) though ..

[JopieK]

Interesting, so LEGO trains actually sound authentic!!

Well, they all use electric PWM motor controllers ;)

[Barduck]

Interestingly my Prius makes the same sounds when rolling slow (say through a parking garage) in "EV" (Electric Vehicle) Mode.

funny you should mention the prius I was just thinking about Jeff Dunham's joke on the sound it makes

http://www.youtube.com/watch?v=qP-tyvBGla4

[1974]

Well, they all use electric PWM motor controllers ;)

No, they don't I'ts only the current ones that do ..

Edited June 10, 2014 by 1974

[Heppeng]

What about the voltage ones?

[JopieK]

No, they don't I'ts only the current ones that do ..

I guess you are right, but it depends on 'all', of course most modern trains will, although the high voltage control will be probably also different from low power version.

These also have the "eeeeee" sound:

http://en.wikipedia.org/wiki/NS_VIRM

[1974]

What about the voltage ones?

I was gonna pull a joke like that, but mine wasn't that good

Well played sir