Vanilla 1.1.9 is a product of Lussumo. More Information: Documentation, Community Support.

    • CommentAuthorsonoboy
    • CommentTimeDec 28th 2009
     
    Just have to assemble tonite. Tomorrow I hope to do a simple test and that will be to drive the rotor to high RPM with compressed air and position just one toroid for minimum open circuit voltage, whatever orientation that takes. The next test will be to see if there is a significant reduction in run-down time with the coil SHORTED. If there is, it'll be pretty much all over except for the crying on the believer side of the fence.
    •  
      CommentAuthorlegendre
    • CommentTimeDec 28th 2009
     
    let's see some photos!
  1.  
    This sounds good, with the proviso that a direct short does not always give the most load that can be put on a generator.

    But if your bearings are good and your technique flawless, I would think you should be able to see the CEMF, especially if you really spin that sucker, as a reduction in rundown time in the "coil shorted" case.

    But the difference is likely to be small, and so you probably should do a number of runs in each condition, with the order randomized to compensate for systematic effects like bearing run-in and so forth. Like do 20 runs, in random order like ABBABBBAAABBABABAAAB decided beforehand, and then take the means and standard deviations of the A and B runs.

    OOH, I can hardly wait.

    Of course if you DO see CEMF, then that falsifies the Steorn claim. However if you do NOT see the CEMF, the claim could still be false, that is, it could be there but you missed it for some reason.
    • CommentAuthorDirtfarmer
    • CommentTimeDec 28th 2009
     
    And it still might not falsify it , due to material sciences possibly involved, and possible winding geometries....
    Goodluck,
    Goodwill,
    -Dirtfarmer
  2.  
    Posted By: alsetalokin
    Of course if you DO see CEMF, then that falsifies the Steorn claim. However if you do NOT see the CEMF, the claim could still be false, that is, it could be there but you missed it for some reason.


    From what I gather, Sonoboy's initial tests will be with an unpowered coil. All electromagnetic effects will be due to interaction with moving rotor magnets. Under these conditions I would expect a significant difference between the open and shorted coil testing.

    A powered test should be added as well, where the coil is continuously provided enough current to saturate the core. Compare spindown time and scope for induction ripples riding on the DC power.
    • CommentAuthorMrEntropy
    • CommentTimeDec 28th 2009 edited
     
    Posted By: alsetalokinOf course if you DO see CEMF, then that falsifies the Steorn claim.

    Not really. With 4 coils wired in series, Steorn can wire two of them in the opposite polarity and then make fine adjustments to coil positions until the CEMF is effectively zero*.



    * For nit pickers: effectively zero means that in the CEMF vs time graph, they can engineer 3 zero crossings with positions chosen to minimize whatever measure of total CEMF they like. CEMF is already small, CEMF waveforms from all coils will be very similar, so they should be able to get very, very close to zero overall if they're careful.
  3.  
    Posted By: MrEntropy
    Posted By: alsetalokinOf course if you DO see CEMF, then that falsifies the Steorn claim.

    Not really. With 4 coils wired in series, Steorn can wire two of them in the opposite polarity and then make fine adjustments to coil positions until the CEMF is effectively zero*.



    * For nit pickers: effectively zero means that in the CEMF vs time graph, they can engineer 3 zero crossings with positions chosen to minimize whatever measure of total CEMF they like. CEMF is already small, CEMF waveforms from all coils will be very similar, so they should be able to get very, very close to zero overall if they're careful.


    Hmm. Of course you are right.

    I'm not sure this qualifies as elimination of CEMF, though. The forward voltage from one coil is opposed by the reverse voltage from the other coil. No net current, no net voltage, but both coils are extracting energy from the rotation to make it so. If one coil is moved out of the magnet's range, the small indicated CEMF will appear since the first coil is no longer opposing it by extracting energy from the rotation.

    Maybe. I think.
    • CommentAuthorMrEntropy
    • CommentTimeDec 28th 2009 edited
     
    If there's no current, then nobody is extracting energy from the rotation.
  4.  
    Posted By: MrEntropy
    Posted By: alsetalokinOf course if you DO see CEMF, then that falsifies the Steorn claim.

    Not really. With 4 coils wired in series, Steorn can wire two of them in the opposite polarity and then make fine adjustments to coil positions until the CEMF is effectively zero*.



    * For nit pickers: effectively zero means that in the CEMF vs time graph, they can engineer 3 zero crossings with positions chosen to minimize whatever measure of total CEMF they like. CEMF is already small, CEMF waveforms from all coils will be very similar, so they should be able to get very, very close to zero overall if they're careful.


    Probably a worthwhile experiment. But those weird images in my head say this configuration would basically nullify any induced current and the resulting partial saturation of the core, something I feel is necessary.
    •  
      CommentAuthoralsetalokin
    • CommentTimeDec 28th 2009 edited
     
    Posted By: MrEntropyIf there's no current, then nobody is extracting energy from the rotation.


    Really? Fascinating.

    So the open secondary of a power transformer won't heat up, then.
    • CommentAuthorMrEntropy
    • CommentTimeDec 28th 2009
     
    Posted By: overconfidentProbably a worthwhile experiment. But those weird images in my head say this configuration would basically nullify any induced current and the resulting partial saturation of the core, something I feel is necessary.

    Yes, it would nullify all induced current. The cores are saturated by the directly applied current.
  5.  
    Never mind, you are likely to be right, no current means no power extracted by the current. I am less sanguine about being able to achieve this in practice; it certainly wasn't a priority for Sean's demo even though the running Orbos likely used this opposite polarity scheme.
    •  
      CommentAuthorAngus
    • CommentTimeDec 28th 2009
     
    Posted By: alsetalokinNever mind, you are likely to be right, no current means no power extracted by the current. I am less sanguine about being able to achieve this in practice; it certainly wasn't a priority for Sean's demo even though the running Orbos likely used this opposite polarity scheme.


    That might explain the odd setup Naudin (may have) used, with alternating magnet directions and coils in series. Not sure about that.
    • CommentAuthorsonoboy
    • CommentTimeDec 28th 2009
     
    I have a pic of the motor assembled without coils or other electronics. How can I post that here?
  6.  
    Posted By: sonoboyI have a pic of the motor assembled without coils or other electronics. How can I post that here?


    Post it somewhere else, like mediafire.com or photobucket.com, then post a link to it here.

    • CommentAuthorsonoboy
    • CommentTimeDec 28th 2009 edited
     
    Here it is:
    http://www.mediafire.com/file/zmgkgz2t5jh/MOTOR.JPG
    The motor has a 4.5 inch plexiglass rotor with 4 stacks of 3--- 1/2 X 1/8 neos at 90 degree spacing (I think grade 35) all same orientation. Shaft is .250 inch stainless, screws are non-magnetic low conductivity stainless, Upper and lower plates are fiberglass reinforced epoxy, posts are 7/8 Delrin plastic 3 inches tall. Bearings are flanged ball bearings with grease dissolved and light machine oil w wd40 substituted. 4 --1/2 inch tall rubber feet.
    • CommentAuthorjoshs
    • CommentTimeDec 28th 2009
     
    Posted By: sonoboyJust have to assemble tonite. Tomorrow I hope to do a simple test and that will be to drive the rotor to high RPM with compressed air and position just one toroid for minimum open circuit voltage, whatever orientation that takes. The next test will be to see if there is a significant reduction in run-down time with the coil SHORTED. If there is, it'll be pretty much all over except for the crying on the believer side of the fence.
    The coupling is so weak that you will need good resolution to see any difference. However, what you can do is put a scope on the windings when you drive with the air gun and see the CEMF that Steorn claim is missing.
    • CommentAuthorDirtfarmer
    • CommentTimeDec 28th 2009
     
    Nice work,
    Make sure those mags are well-affixed...
    Goodwill,
    -Dirtfarmer
    • CommentAuthorjoshs
    • CommentTimeDec 28th 2009
     
    Posted By: overconfident
    Posted By: alsetalokin
    Of course if you DO see CEMF, then that falsifies the Steorn claim. However if you do NOT see the CEMF, the claim could still be false, that is, it could be there but you missed it for some reason.


    From what I gather, Sonoboy's initial tests will be with an unpowered coil. All electromagnetic effects will be due to interaction with moving rotor magnets. Under these conditions I would expect a significant difference between the open and shorted coil testing.

    A powered test should be added as well, where the coil is continuously provided enough current to saturate the core. Compare spindown time and scope for induction ripples riding on the DC power.
    To do that he should drive with a constant current source. Even a power supply set for constant current can be a problem due to the large output capacitors that are part of most bench supplies.
    • CommentAuthorjoshs
    • CommentTimeDec 28th 2009
     
    Posted By: alsetalokin
    Posted By: MrEntropy
    Posted By: alsetalokinOf course if you DO see CEMF, then that falsifies the Steorn claim.

    Not really. With 4 coils wired in series, Steorn can wire two of them in the opposite polarity and then make fine adjustments to coil positions until the CEMF is effectively zero*.



    * For nit pickers: effectively zero means that in the CEMF vs time graph, they can engineer 3 zero crossings with positions chosen to minimize whatever measure of total CEMF they like. CEMF is already small, CEMF waveforms from all coils will be very similar, so they should be able to get very, very close to zero overall if they're careful.


    Hmm. Of course you are right.

    I'm not sure this qualifies as elimination of CEMF, though. The forward voltage from one coil is opposed by the reverse voltage from the other coil. No net current, no net voltage, but both coils are extracting energy from the rotation to make it so. If one coil is moved out of the magnet's range, the small indicated CEMF will appear since the first coil is no longer opposing it by extracting energy from the rotation.

    Maybe. I think.
    This would reduce the percieved CEMF but will still not eliminate it. The CEMF integral with respect to time is asymmetric. Alternating polarities would tend to show just the net difference EMF that drives the motor.