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Old Aug 22, 2014, 12:00 AM
Smasher of foam
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United States, OH, Stow
Joined Sep 2012
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How does an ESC make my motor beep?

I've been spending my week swapping motors and ESCs around, and for the first time after two years of flying, I just discovered that ESCs don't beep, the motors beep!

And I just read the instruction sheet that came with a turnigy plush ESC and it even writes out the melodies in numbered solfege!

So, anyway, how are the ESCs making the motors sing? Do they work somehow like regular speakers? (e.g., a magnet vibrates a membrane) If they do, then maybe there's a possibility to make motor/speakers.... For some reason.
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Old Aug 22, 2014, 12:02 AM
Smasher of foam
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United States, OH, Stow
Joined Sep 2012
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(If you don't know what "numbered solfege" is, it just means replacing the old "do, re, mi, fa, sol, la, ti" with "1234567.")
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Old Aug 22, 2014, 12:46 AM
homo ludens modellisticus
Ron van Sommeren's Avatar
The Netherlands, GE, Nijmegen
Joined Feb 2001
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Motor acts as a poor loudspeaker. Current in a magnetic field creates a force, something moves/oscillates (wire/coils?, drum?, stator?)

Vriendelijke groeten Ron
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Old Aug 22, 2014, 01:30 AM
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if you rapidly switch power from one phase of the motor to another the rotor of the motor will vibrate, the frequency of switching controls the pitch produced.

Not very efficient or high quality sound production, but it does work.
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Old Aug 22, 2014, 01:24 PM
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Ampère’s law dictates that any time you have a coil of wire in proximity to a magnet, you can apply a voltage and it will move, or move it and it will develop a voltage. If you connect one phase of a motor up to a regular audio amplifier it will behave as a (rather poor) speaker that can play music. Note that if you actually try this, you'll want to use an amp you don't particularly care about since the impedance will probably not be all that close to the 8 Ohms most amps expect.
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Old Aug 22, 2014, 06:32 PM
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Ampere's Law? I am thinking Faraday's Law but all those early electricians were geniuses and we owe them a great big THANK YOU

Okay, I just did a little research and both Ampere and Faraday have laws about magnetic fields and conductors and their interactions so it is likely a combination of both. The part I don't understand is how all those electrons have time to study all those laws, and still keep the lights on.
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Old Aug 22, 2014, 08:17 PM
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Originally Posted by Mike Dubovsky View Post
Ampere's Law? I am thinking Faraday's Law but all those early electricians were geniuses and we owe them a great big THANK YOU

Okay, I just did a little research and both Ampere and Faraday have laws about magnetic fields and conductors and their interactions so it is likely a combination of both. The part I don't understand is how all those electrons have time to study all those laws, and still keep the lights on.
No you're absolutely right, I got the two crossed in my head. It is indeed Faraday's law, though both cover the relation between electricity and magnetism.
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Old Aug 22, 2014, 10:17 PM
You can call me Pat
United States, FL, Tampa
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what an excellent question posed here...
i often wondered this myself. for some reason I thought the motor had some kind of device built in that made the noise.
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Old Aug 23, 2014, 04:55 AM
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Originally Posted by desertstalker View Post
if you rapidly switch power from one phase of the motor to another the rotor of the motor will vibrate, the frequency of switching controls the pitch produced.

Not very efficient or high quality sound production, but it does work.
Whys it vibrate because of electricity? Is it to the same frequency as the controller switches? And what about if the controller just sends elec to one phase what happens?

On another note, I dropped my exposed motor stator on its head on the concrete! It was in its swaddling and someone wanted to see and this and that and I'm feeling maybe it was me and I was negligent. What are my chances of it having irreparable damage and when will I find out?! Maybe after it's all said and done I'll never know if it's head fall caused damage and I'll just think that's my motor. I want the best for my motor though. I want it to have a long life and be the best motor it can be. What's a responsible motor owner supposed to do?
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Old Aug 23, 2014, 05:02 AM
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On another note, I dropped my exposed motor stator on its head on the concrete!
A bare stator? Only damage to worry about is physical, if it looks OK it will run OK too.
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Old Aug 23, 2014, 09:48 AM
homo ludens modellisticus
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The Netherlands, GE, Nijmegen
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Originally Posted by pdooley View Post
... i often wondered this myself. for some reason I thought the motor had some kind of device built in that made the noise.
Nothing to hide
More drawings and pictures
www.aerodesign.de/peter/2001/LRK350/index_eng.html




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Old Aug 23, 2014, 06:46 PM
Wake up, feel pulse, be happy!
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United States, AK, Fairbanks
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A brushless motor and an audio speaker share a whole bunch of DNA. Many moons ago, I was able to get a parkflyer motor to play actual music by connecting two of its leads to the headphone output of my iPod. It was extremely faint, but songs were recognizable. I'm sure a more powerful speaker output would increase the volume to listen-able levels.

Brushless motors by themselves aren't great at making noise, but our big, light foam and wood airframes work great for amplifying sound. Personally, I'm still waiting for an ESC that allows users to assign their own sound clips for various functions
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Old Aug 23, 2014, 08:55 PM
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Crank one of those miniature music box mechanisms in free air and you can barely hear it. Screw it to a block of wood and you can listen to it across the room. If you attach a brushless, or brushed for that matter motor to a suitable resonator and connect it to an audio amplifier, you can get reasonably decent sounding music out of it. A speaker is nothing more than a coil of wire mounted to a movable cone in proximity to a magnet. You can build a perfectly reasonable sounding speaker from scratch quite easily.

Anyway back to the speed controllers that play tones, they just switch the transistors driving two of the windings at the frequency of the tones you hear. The motor vibrates at that frequency and you hear the sound.
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Old Aug 23, 2014, 09:20 PM
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Tel Aviv, Israel
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Floppy Music | Eurythmics - Sweet Dreams (12 Drives) (3 min 11 sec)


the stepper motors used on smaller CNC machines are also getting in on the act.
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Old Aug 27, 2014, 03:00 PM
Jack
USA, ME, Ellsworth
Joined May 2008
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Quote:
Originally Posted by FunkeyMonk View Post
I've been spending my week swapping motors and ESCs around, and for the first time after two years of flying, I just discovered that ESCs don't beep, the motors beep!

And I just read the instruction sheet that came with a turnigy plush ESC and it even writes out the melodies in numbered solfege!

So, anyway, how are the ESCs making the motors sing? Do they work somehow like regular speakers? (e.g., a magnet vibrates a membrane) If they do, then maybe there's a possibility to make motor/speakers.... For some reason.
There is a little guy in the with a horn . They wake him up and give him electric shocks.

Actually it has to do with rapidly changing or pulsating the current and/or polarities on the windings. It is sort of amazing. though, it turns the motor into a speaker of sorts. What you hear can vary in pitch and volume from motor to motor and with the voltage your using.

Jack
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