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Old August 4th 08, 01:11 AM posted to rec.aviation.homebuilt
Ernest Christley
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Posts: 199
Default Coaxial generator development

wrote:
On Aug 2, 11:17 pm, Ernest Christley wrote:

I need to verify, but I'm fairly certain that the reg/rec I'm using is a
switching type. It turns off the line when the power isn't needed.
Saving the generator from producing heat in both the rotor/stator and
generator.

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Dear Ernest,

I'm afraid that only addresses the power OUTPUT, not generation. So
long as the magnetic field is present and is being cut by the winding
of the coil, a voltage WILL appear across the coil, as will some
residual heating effects. The regulator can isolate this from the
battery but that only addresses the output-side of the equation.


Yes, it does keep producing a voltage, and possibly an extremely high
one at that; but heat comes from work, and a voltage is only half of
that equation. You need to move some AMPS with that voltage to heat
things up. The magnets will push the electrons as hard as they can be
pushed, but the switching regulator has opened the circuit. The
electrons bang into a wall, all jumbled together at the end of the wire.
Once the magnet passes, the little guys will relax and spread out a
bit until the next magnet comes along to push them all up against the
wall again. Thus, there is some current flow, but it is AC and in the
milliamp range.

It's easy enough to test. Run one with no load for a while. That
includes taking the regulator out of the circuit. Those older style
regulators worked by acting like a fat resistor to dump excess power,
making sure that the generator ran at full load all the time. Dollars
to donuts (yeah, I know, not a great deal anymore) that the generator
will be cooler than most of the other engine parts.

Now, put a headlamp on as a load, and run it again. You'll need the
regulator this time. You could even run it with just your regulator
(but, that's hard on the regulator). I bet another dollar that the
generator heats right up. Probably warm enough to cook that donut.

That's a guess of course -- we're using different components. But in
a permanent-magnet type dynamo the Field is always 'on' so to speak --
there is no 'control' as is found in the typical generator-type dynamo
since there is no Field winding. In either case, I think your method
of installation calls for a bit more head-work.

-R.S.Hoover


A critical piece that doesn't really come across in the pictures is that
there is a very strong air stream passing over and around the generator.
In fact, the final goal is for it to be on the inside of a centrifugal
blower. The one thing I do have left to do is to add a splash guard that
will keep debris from filling up the rotor over time, but that will be
simple enough to do.

I went out to take this picture. Used the Gimp to highlight the air
intake areas that will provide cooling air. The pattern continues all
the way around the gearbox.

http://ernest.isa-geek.org/Delta/Pic...AndCooling.jpg