Lovely page! Thanks, Harry! JLN has done a really clear job of describing the effect, well enough that it can be reproduced and fully analyzed, with, as far as I can see, no hidden tricks.
Now, what can we say about his page? First, he measures the inductance of the coil, and observes that it's lower when the magnets are nearby. OK, well and good; as I understand it that's because the core is saturated and its permeability has hit the skids. Next, he shows the voltage, current, and power curves to energize/deenergize the coil with and without the magnets present. He asserts, several times in a couple different ways: > KEY 3 : The electrical power (Current * Voltage ) needed to energize the > toroidal stator coil at the TDC position is EQUAL to the electrical > power for the REF position and this is fully independant of the position > of the magnet of the rotor Vs the toroidal stator coil. The electrical > input power is fully decoupled from the output mechanical power. Now it may not matter with regard to the final analysis of this motor (which probably must depend on calorimetry), but it's interesting to note that this several times repeated assertion is FALSE. This can be seen by simple reasoning, and by looking at his curves. First, simple reasoning: When the magnets are present, the inductance of the coil is lower. So, by definition of inductance, when the voltage is turned on, the current is going to rise and fall *faster* with the magnets present than with them absent. That means total power going in during turn-on is going to be higher with the magnets present than with them absent, and total power going in during turn-off is going to be lower with the magnets present than with them absent. Consequently, power consumed is going to be larger if the magnets are brought to the coil, the power is turned on, the magnets are removed, and power is turned off, than it would be if the magnets were either left far away throughout the cycle, or were left adjacent to the coil throughout the cycle. Second, look at the curves: The power curve, shown most of the way down the web page, is clearest on this point. The RED curve, magnets present, goes up faster and comes down faster. If you bring up the magnets, turn on the power, take the magnets away, and then turn off the power, you get the RED curve going up and the BLUE curve coming down, and the result is that you're on the "higher consumption" curve going up *and* coming down. So, again, power consumed is higher if the motor is running than if it's shut off. So, JLN has mis-stated things: Power consumed is not independent of the placement of the magnets. Without careful measurements we can't know how big the difference is, but there clearly is a difference. As with all magnetic shields, the only place where you can see any power being consumed is as the shield is switched on and off. Look at the rise and fall -- don't look at the flat peak, it's just a red herring. Now, the other issue is warming of the core. As I understand it, when the core is saturating, things are not behaving "elastically" and some energy is being lost to heat. I *think* that amount is different depending on whether the core starts out saturated (by the external magnets) or doesn't. That heat must be measured to get a full energy balance of the motor, and of course JLN hasn't done that in this series of experiments. But once again, I'd like to say I think this is a great page; by putting everything down, in detail, with measurements and specifications, JLN has made it possible to fully analyze exactly what is going on, and determine once and for all where the energy is going and where it is coming from. Excellent! On 02/09/2010 02:16 PM, Harry Veeder wrote: > Understanding the Orbo principle by JL Naudin > > http://jnaudin.free.fr/steorn/html/orboeffecten.htm > > > Harry > > > > __________________________________________________________________ > Looking for the perfect gift? Give the gift of Flickr! > > http://www.flickr.com/gift/ >
