How to Spot a Psychopath

A couple of people have forwarded this article to me, about a fellow called Thane Heins who seems to be claiming (in essence) that he's made a motor with better than 100% efficiency.

I, of course, will believe it when I see it. And I don't expect to ever see it.

But the hook in the article is that Professor Markus Zahn of MIT was impressed - or at least confused - by the demonstration.

There's no real information about what actually happened in the demonstration, though. The closest they come to telling you is saying "He holds a permanent magnet a few centimetres away from the driveshaft of an electric motor, and the magnetic field it creates causes the motor to accelerate."

Well, yeah. Of course it does.

If you put stronger magnets in a permanent magnet motor, it'll give you more power from a given voltage. And consume more current. Its efficiency will probably actually drop.

And you certainly can demonstrate this effect by moving a powerful magnet close to a motor, such that the field from the external magnet supplements the field from the magnets inside the motor.

Behold, My Very First Metacafe Video, demonstrating the phenomenon with an unsuspecting motor and a honkin' great magnet:

Note the current and voltage displays on the power supply that's running the motor. The voltage stays where I set it (when it's not being pushed around by back EMF when the motor slows down), but the current - and thus the consumed power - spikes massively when I'm "supplementing" the motor's own magnetic field.

You can do this same thing more efficiently if you replace a permanent magnet motor's internal magnets with more powerful versions. But a field is a field; the motor doesn't much care where the field comes from.

This is why, for instance, there are restricted model car and aircraft racing leagues that only let you use cheap ferrite-magnet motors. I remember a friend telling me about a dude whose plane was faster than everyone else's and nobody could quite figure it out, until they noticed that the "magnetic latch" on his battery bay, right under the motor, contained the most powerful rare earth magnet ever used for such an application.

I hope there's something more to Thane Heins' discovery than this, but I wouldn't be at all surprised if all he's done is embroidered on the idea by, say, switching electromagnetic coils outside a permanent magnet motor to put the field supplementation where it'll do the most good at each point in the motor's rotation. Which also won't give you any more efficiency than a number of existent motor designs.

Here's Thane himself, explaining his invention:

I don't know enough about this stuff to know whether what he says makes any sense at all, but I suspect he's asking back EMF to do things that it won't actually do.