Working Magnetic Motor on you tube??

[Omnibus]

@Yadaraf,

Thanks. Now, the purpose of this exercise is to see whether we can recover the rpm of the stator and rotor from the audio spectrum of the device.

Thus, we know that the rotor turns at ~250rpm and therefore the stator turns at ~4 x 250 = 1000rpm. Let?s see if this is what we?ll get from the spectrum.

First clear peak is at 963Hz which may mean that 963 times per second or 963 x 60 times per minute there was an event (for instance, passing of a pole of the rotor by the stator). A rotor has 8 poles, therefore, every minute there were (963 x 60)/8 = 7222 full turns of rotor or the rotor was spinning at 7222rpm. Not so, though, as is known from the condition of this problem. Therefore, this peak tells us nothing about the rotor rate of rotation. Neither for rate of spinning of the stator.

One may consider one earlier peak at around 600Hz but then again (600 x 60)/8 = 4500rpm. Nowhere near the known rates of rotation of rotor and stator.

The peaks in kHz region aren?t even first and second harmonic and are obviously to be excluded for the purpose of this exercise.

Therefore, a spectrum such as this cannot serve as a measurement of the rotor and stator rpm but gives a more general fingerprint of the acoustic behavior of the device probably more reflective of things such as the inexactness of the bearings causing a clatter due to wobbling, different noises due to friction losses, general vibration of the structure etc.

Probably, it will be interesting to compare it to the previous spectra of the same device (taken during its wind down) but I guess the conclusion will be the same?the wind down spectra only show the general acoustic behavior of the device during that period of wind down.

This is what seems to be the most plausible conclusion from this spectral analysis. What do you think?

[Omnibus]

.

[Yadaraf]

@Yadaraf,

Thanks. Now, the purpose of this exercise is to see whether we can recover the rpm of the stator and rotor from the audio spectrum of the device.

Thus, we know that the rotor turns at ~250rpm and therefore the stator turns at ~4 x 250 = 1000rpm. Let?s see if this is what we?ll get from the spectrum.

First clear peak is at 963Hz which may mean that 963 times per second or 963 x 60 times per minute there was an event (for instance, passing of a pole of the rotor by the stator). A rotor has 8 poles, therefore, every minute there were (963 x 60)/8 = 7222 full turns of rotor or the rotor was spinning at 7222rpm. Not so, though. Therefore, this peak tells us nothing about the rotor. Neither for rate of spinning of the stator.

One may consider one earlier peak at around 600Hz but then again (600 x 60)/8 = 4500rpm. Nowhere near the known rates of rotation of rotor and stator.

The peaks in kHz region aren?t even first and second harmonic and are obviously to be excluded for the purposes of this exercise.

Therefore, a spectrum such as this cannot serve as a measurement of the rotor and stator rpm but gives a more general fingerprint of the acoustic behavior of the device probably more reflective of things such as the inexactness of the bearings causing a clatter due to wobbling, different noises due to friction losses, general vibration of the structure etc.

Probably, it will be interesting to compare it to the previous spectra of the same device (taken during its wind down) but I guess the conclusion will be the same?the wind down spectra only show the general acoustic behavior of the device during that period of wind down.

This is what seems to be the most plausible conclusion from this spectral analysis. What do you think?

Omni,

See my hypothesis on the 5th harmonic.  FunkyJive's a musician and might have an observation.  What doesn't fit, however, is that the amplitude of the 5th -- if that's what it is -- is higher than the fundamental.

... 5th harmonic:  http://www.overunity.com/index.php/topic,3871.msg76194.html#msg76194

I keep thinking of CLaNZeR's video in which he discusses bearing noise.  Great video as usual.  The noise -- and tones like in Andrea's rig -- are peculiar to be sure.

... Bearing Noise:  http://www.overunity.org.uk/ocpm/CLaNZeRSBearingnoise.wmv

I agree that the HI/LO tones probably are not related to race noise.  Also, recall that Bruce's rig did not have spinning stators, and it still generated interesting tones.  I'm scratching my head.    


Cheers,   

Yada..
.

[blue_energy]

@Yadaraf,

Here's the sound bit this time with tails of background. Also, who knows, I've become a little more skilled in turning the rotor by hand so I could keep it almost within 240-260rpm range. Sorry for the delay. And, yes, I'm on the east coast--NYC.

Omni,

Here you go.  I think the baseline worked well.      Note in the baseline that is a persistent spike.

Not sure what you can conclude, however ...


Cheers,   

Yada..
.

Wow!  Just back from seeing Victor Lamont Wooten in concert in a bar!  My God!  To be able to play like that...

OK - I just stopped in to say to Omnibus:

If you want to compare apples to apples - your rig to Alsetalokin's - you need to spin the stator up to 5220 rpm.  All rotor or stator dependent frequencies will vary with the speed of the stator and or rotor.  That was the significance of the 174 Hertz test: Al's rig only produces the 174 Hz tone when spinning at full speed - and we can hear it slowly rev up to that.  If your rig and Al's are identical, you won't get that harmonic unless your rig is spinning the same speed his was - which we, at least, think we've narrowed down to 5,220 on the stator and 1,305 on the rotor.  I think it's quite likely that there are other frequencies which are movement related as well.

Do you have any means at your disposal to speed the rotor up to 1305?  Dremel buffer?  Compressed air?

I'm going to try speeding up your audio to attempt to simulate somewhere around 1305.  If it was at 250 rpm, I'll quadruple the speed to raise it to 1,000 rpm.  That should also increase whatever sound is there by 2 octaves - which might make it stand out.  Unfortunately, I don't have the skill to figure out what I'd have to do get it to 1,305.  Octaves are easy because each octave up is double the current frequency.

I don't hold out too much hope for this plan, however.  It's a hack - but it's a cludge.  It would be better if you could produce a test sample which is the same speed as Alsetalokin's.

[Yadaraf]

@Yadaraf,

Here's the sound bit this time with tails of background. Also, who knows, I've become a little more skilled in turning the rotor by hand so I could keep it almost within 240-260rpm range. Sorry for the delay. And, yes, I'm on the east coast--NYC.

Omni,

Here you go.  I think the baseline worked well.      Note in the baseline that is a persistent spike.

Not sure what you can conclude, however ...


Cheers,   

Yada..
.

Wow!  Just back from seeing Victor Lamont Wooten in concert in a bar!  My God!  To be able to play like that...

OK - I just stopped in to say to Omnibus:

If you want to compare apples to apples - your rig to Alsetalokin's - you need to spin the stator up to 5220 rpm.  All rotor or stator dependent frequencies will vary with the speed of the stator and or rotor.  That was the significance of the 174 Hertz test: Al's rig only produces the 174 Hz tone when spinning at full speed - and we can hear it slowly rev up to that.  If your rig and Al's are identical, you won't get that harmonic unless your rig is spinning the same speed his was - which we, at least, think we've narrowed down to 5,220 on the stator and 1,305 on the rotor.  I think it's quite likely that there are other frequencies which are movement related as well.

Do you have any means at your disposal to speed the rotor up to 1305?  Dremel buffer?  Compressed air?

I'm going to try speeding up your audio to attempt to simulate somewhere around 1305.  If it was at 250 rpm, I'll quadruple the speed to raise it to 1,000 rpm.  That should also increase whatever sound is there by 2 octaves - which might make it stand out.  Unfortunately, I don't have the skill to figure out what I'd have to do get it to 1,305.  Octaves are easy because each octave up is double the current frequency.

I don't hold out too much hope for this plan, however.  It's a hack - but it's a cludge.  It would be better if you could produce a test sample which is the same speed as Alsetalokin's.

Blue,

Bela Fleck is awesome.  One of my favs.  Just got into them a couple of years ago.

Q:  What's your reference for 5220 RPM? 

@02:57 on the WMV video I can read "4733" on the LCD and hear Al say: "OK, so now we're over 4000 -- almost 5000 RPM on that small magnet."   


Cheers,   

Yada..
.