An electric motor that uses the Earth's magnetic field as field magnets.
When externally powered, the brushes would have to be lined up with the Earth's magnetic field in order to operate with any semblance of efficiency.
The application of a spintop such as <link> would probably be the most interesting due to its one-piece design: it uses a self-contained solar cell for power, and a crude gaussmeter to sense when to energize its armatures. Note that it must be started manually in order to energize the gaussmeter.
(still working on a descriptive name: there's an existing "Geomagnetic Motor" on the web which looks a bit scammy... haven't checked it out in any detail yet: broken English gives me a headache)-- FlyingToaster, Jan 10 2011 One of the few applications Solar_20Powered_20G...Motion_22_20Spintop [FlyingToaster, Jan 10 2011, last modified Jan 11 2011] Very fast spinning rotor very_20fast_20spinning_20rotorSee main idea and look down for my comment about using Earth's magnetic fiield [Ling, Jan 11 2011] // brushes //
I'm pretty sure you'd want this to be brushless.-- RayfordSteele, Jan 10 2011 Brushless DC uses permanent magnets as rotors, and coils on the outside, ie: it's an "inside out" brush model. The top <linked> uses a solar cell which is on the rotor so there's no brush.-- FlyingToaster, Jan 11 2011 Using solar cells gives some kind of directional information (at least "up and down").
See link-- Ling, Jan 11 2011 Obviously great minds do think alike :)
Have you given any more thought to that ?-- FlyingToaster, Jan 11 2011 A coil-magnetometer is a compass of sorts. This is a coil-magnetometer operating in reverse.
You'd want(/need) to line up the brushes with the Earth's magnetic field so you switch polarity on the armatures at the right time.-- FlyingToaster, Jan 11 2011 FT, //Have you given any more thought to that ?//
After I blasted the workshop with shrapnel? I must admit, each time I pick some out of my body, the thought crosses my mind.-- Ling, Jan 12 2011 random, halfbakery