In your URL you say the transistor got very hot, that means
too much current is being drawn. Did you look at it on a
scope to see if you were getting high amplitude, short
duration spikes? And I would think the frequency must match
only what the rpm X # magnets equals to provide the drive.
Not that it matters much if its not giving the pulses, but
here are the specs for the MPS8099.
The MPS8099 is rated;
BVCEO IC(max) PD(max) hFE(min) fT(min)
MPS8099* 80 V 0.2 A 350 mW 100 150 MHz
I haven't built mine yet so don't have any room to talk or
suggest, but it would seem by arranging a torus type coil
around the wheel so that the line of magnetic force would
pass through multiple series windings, it should induce
current that could run the thing or at least help to
recharge a battery.
If the shaft was being driven, then it could be attached to
a bicycle generator (about $8-12.00) at most any Wal-Mart
type store where high speed rotation would produce a
current.
With just the wheel spinning freely on a bearing that is
simply supported by a shaft, the coil arrangment would
provide the same ability to produce current, though whether
or not it could recharge the battery AND have enough left
over to do work is questionable at this point...
Maybe John can have the little girl modify her
experiment..<g>....and find out...
"Dan [FrogEStyle]" wrote:
>
> I built a couple and if you would like a look you can check out my page:
> http://www.gower.net/jfrog/bedinimo.htm
>
> I have had problems with the switching...
> The batts did run down.
>
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