Proper impeller play on a Union (Con-tec)dynamo?

On Tue, 17 Nov 2020 09:02:49 -0800, Tom Kunich wrote:

On Tuesday, November 17, 2020 at 8:54:15 AM UTC-8, Frank Krygowski
wrote:

Just admit you were wrong (yet again) and stop typing.

You were asked a question and you speak of me deflecting? If a dyno hub
has drag when no current is being drawn, it has been improperly
designed.

Could I design one that works without drag? Yes, it is NOT
very difficult. You separate the magnets from the conductors when it is
not in use. But you didn't even know that did you? Instead you blabber
on as the all knowing freak of nature you consider yourself.

Gee Tommy, I wonder why no one has ever brought out a bicycle hub that
provided that option?

Apart from having two wheels, one with a dyno and one without a dyno.

On 11/17/2020 10:48 AM, Frank Krygowski wrote:
On 11/17/2020 1:11 PM, Tom Kunich wrote:
On Tuesday, November 17, 2020 at 10:01:22 AM UTC-8, Mark J. wrote:
On 11/17/2020 9:26 AM, AMuzi wrote:
On 11/17/2020 11:02 AM, Tom Kunich wrote:
On Tuesday, November 17, 2020 at 8:54:15 AM UTC-8, Frank Krygowski
wrote:
On 11/17/2020 11:45 AM, Tom Kunich wrote:
On Monday, November 16, 2020 at 11:14:15 AM UTC-8, Frank Krygowski
wrote:
On 11/16/2020 1:55 PM, Tom Kunich wrote:
On Monday, November 16, 2020 at 9:31:59 AM UTC-8, Frank Krygowski
wrote:
On 11/16/2020 11:36 AM, Tom Kunich wrote:

Unless you're drawing current from generator hubs they shouldn't
be offering any drag at all. They have no friction surfaces and
like all generators only offer resistance when they are in use.
"Shouldn't be offering any drag at all" is true only in the
aspirational
sense. They all have some drag (usually minor) when off, due
to eddy
current losses if nothing else. This is documented through many
tests by
many different investigators. There are have even been a few
models that
have less drag on than off.

Really, Tom, you should do a _little_ study before posting.

--
- Frank Krygowski

Really Frank, you should know that in a properly designed
generator there would be no eddy currents generated unless and
until there was an actual current flow pathway.
You're talking about the difference between theory and practice.

In theory, they're they same. In practice they are not.
Not having use the Shimano generator in a long time I was unaware
that they were improperly designed.
But you have no reluctance about posting, of course.

See https://www.cyclingabout.com/dynamo-...g-lab-testing/ along
with many other articles on the subject.

It seems by your standards, even the best are improperly designed.
Could
it be the designers know more than you do?

Tell us Frank, why do you think that Tesla's do not have
regenerative braking or decelerate when you pull your foot off the
pedal? You're an engineer and you're saying that in practice you
can't avoid eddy currents. So HOW has Tesla done it?
Tom is once again babbling away in an attempt at deflection.

Focus, Tom, focus! You said bicycle hub dynos have no additional drag
when turned off. You're wrong, as every relevant test has shown.

I'm sure that somewhere in your fantastic resume you have the part
where
Elon Musk personally hired you to completely eliminate drag from
coasting Teslas. But that's not what we were talking about.

Just admit you were wrong (yet again) and stop typing.

You were asked a question and you speak of me deflecting? If a dyno
hub has drag when no current is being drawn, it has been improperly
designed. Could I design one that works without drag? Yes, it is NOT
very difficult. You separate the magnets from the conductors when it
is not in use. But you didn't even know that did you? Instead you
blabber on as the all knowing freak of nature you consider yourself.


Spin one in your fingers, no wire.
There's bearing drag and an eddy current.
While I agree with Frank completely and know that Tom is just completely
wrong on this thread...

Spinning modern dynamo hubs with fingers at the axle *greatly*
exaggerates their drag. Take the same wheel and spin it mounted to a
frame. It will spin far longer than one would expect from the
finger-axle-spin test.

I *think* what is going on is that the dynamo greatly resists motion for
some small fraction of a turn *then* propels the axle forward a similar
small distance. The ?stator? ?rotor? nearly "snaps" from one position
to the next. On *average*, over a full rotation, there's only a small
drag, but nowhere near as much as one feels during that first small bit
of twisting the axle.

Finally, not all hub dynamos are created equal, as the drag tests that
Frank cites clearly show. Some have pretty much the same drag with
light on as light off(!) (I think older/cheaper Shimanos fall in this
category), the good ones don't. I'll give a gratuitous plug for SP
dynamos as being among the best in this regard; I own two.

Mark, how much of that resistance is because of the brushes? Since the
poles of a DC motor (from memory) are laminated iron sheet
specifically to prevent eddy currents you wouldn't expect them to be
much of a problem would you? I would expect the brushes to be the
problem and not the eddy currents.

Oh good grief, such technical ignorance!

Hub dynos and other bike dynos don't have brushes because they don't
need them. The magnets rotate. The coils that deliver the output are
stationary and are directly connected to the output wiring. The dynos
put out AC current. There is no need for a commutator to convert it to
DC, and if there were such a need, these days it would be done with
electronics, not brushes.

Sheesh!

What Frank said.

I built an electric motor out of enamel wire, nails, a bent steel bar, a
wood base, cloth "electrical tape," and lots of fussing in ?5th? grade
following a design in the ?Boy Scout manual? or something like that,
even though I wasn't a Boy Scout.

Getting the "brushes" to work was a real fussy bit. Better to leave
them out of your design if you can. Since it didn't have a permanent
magnet, I gather it could NOT(?) be operated as a generator.

As it turned out, the 1.5V "dry cell" battery I had wasn't enough to
spin this kludge job, so we tested it with the family car's battery and
it spun and sparked. As Dad said, "there's no substitute for
horsepower" -- or voltage. But I couldn't take that battery to the
science fair, so no demonstration there, and no prize.

I later pulled a brushless AC induction motor out of a broken ?record
player?. No physical contact between the rotor and wiring, just
?non-conductive? contact at the rotor bearing between rotor and
magnet/body. And the rotor was copper - a non-magnetic metal. Couldn't
understand how it worked until college physics (guess that makes me a
snooty elite college boy) but it was impressive to me.

Mark J.

On Tue, 17 Nov 2020 13:20:57 -0800, Tom Kunich wrote:

I had a hub generator when I was touring but that was more than 20 years
ago and my memory is now shot from that concussion. It is possible to
make very much better generators today since we now have "super magnets"
which weren't available before. Real super capacitors do not exist yet
but I suppose using large capacitors they can even out the ripple from a
DC Generator.

Super magnets would just require more work to overcome the eddy effect.
IME, bicycle Dyno hubs are NOT DC generators. They are AC generators.
Putting AC into a capacitor does not accumulate charge on the capacitor.
It requires some form of rectification, like a capacitor.The historical
trick was finding a suitable diode that didn't let out the magic smoke
going down a good hill, versus doesn't reduce the voltage output too
much.

On Tue, 17 Nov 2020 09:02:49 -0800 (PST), Tom Kunich
wrote:

On Tuesday, November 17, 2020 at 8:54:15 AM UTC-8, Frank Krygowski wrote:
On 11/17/2020 11:45 AM, Tom Kunich wrote:
On Monday, November 16, 2020 at 11:14:15 AM UTC-8, Frank Krygowski wrote:
On 11/16/2020 1:55 PM, Tom Kunich wrote:
On Monday, November 16, 2020 at 9:31:59 AM UTC-8, Frank Krygowski wrote:
On 11/16/2020 11:36 AM, Tom Kunich wrote:

Unless you're drawing current from generator hubs they shouldn't be offering any drag at all. They have no friction surfaces and like all generators only offer resistance when they are in use.
"Shouldn't be offering any drag at all" is true only in the aspirational
sense. They all have some drag (usually minor) when off, due to eddy
current losses if nothing else. This is documented through many tests by
many different investigators. There are have even been a few models that
have less drag on than off.

Really, Tom, you should do a _little_ study before posting.

--
- Frank Krygowski

Really Frank, you should know that in a properly designed generator there would be no eddy currents generated unless and until there was an actual current flow pathway.
You're talking about the difference between theory and practice.

In theory, they're they same. In practice they are not.
Not having use the Shimano generator in a long time I was unaware that they were improperly designed.
But you have no reluctance about posting, of course.

See https://www.cyclingabout.com/dynamo-...g-lab-testing/ along
with many other articles on the subject.

It seems by your standards, even the best are improperly designed. Could
it be the designers know more than you do?

Tell us Frank, why do you think that Tesla's do not have regenerative braking or decelerate when you pull your foot off the pedal? You're an engineer and you're saying that in practice you can't avoid eddy currents. So HOW has Tesla done it?
Tom is once again babbling away in an attempt at deflection.

Focus, Tom, focus! You said bicycle hub dynos have no additional drag
when turned off. You're wrong, as every relevant test has shown.

I'm sure that somewhere in your fantastic resume you have the part where
Elon Musk personally hired you to completely eliminate drag from
coasting Teslas. But that's not what we were talking about.

Just admit you were wrong (yet again) and stop typing.

You were asked a question and you speak of me deflecting? If a dyno hub has drag when no current is being drawn, it has been improperly designed. Could I design one that works without drag? Yes, it is NOT very difficult. You separate the magnets from the conductors when it is not in use. But you didn't even know that did you? Instead you blabber on as the all knowing freak of nature you consider yourself.

See
https://www.cyclingabout.com/dynamo-...ision-shimano/

You ignorant oaf.
--
Cheers,

John B.

On Tue, 17 Nov 2020 21:16:57 +0100, Tosspot wrote:

On 17/11/2020 17:45, Tom Kunich wrote:
On Monday, November 16, 2020 at 11:14:15 AM UTC-8, Frank Krygowski
wrote:
On 11/16/2020 1:55 PM, Tom Kunich wrote:
On Monday, November 16, 2020 at 9:31:59 AM UTC-8, Frank Krygowski
wrote:
On 11/16/2020 11:36 AM, Tom Kunich wrote:

Unless you're drawing current from generator hubs they
shouldn't be offering any drag at all. They have no friction
surfaces and like all generators only offer resistance when
they are in use.
"Shouldn't be offering any drag at all" is true only in the
aspirational sense. They all have some drag (usually minor)
when off, due to eddy current losses if nothing else. This is
documented through many tests by many different investigators.
There are have even been a few models that have less drag on
than off.

Really, Tom, you should do a _little_ study before posting.

-- - Frank Krygowski

Really Frank, you should know that in a properly designed
generator there would be no eddy currents generated unless and
until there was an actual current flow pathway.
You're talking about the difference between theory and practice.

In theory, they're they same. In practice they are not.
Not having use the Shimano generator in a long time I was unaware
that they were improperly designed.
But you have no reluctance about posting, of course.

See https://www.cyclingabout.com/dynamo-...g-lab-testing/
along with many other articles on the subject.

It seems by your standards, even the best are improperly designed.
Could it be the designers know more than you do?

Tell us Frank, why do you think that Tesla's do not have regenerative
braking or decelerate when you pull your foot off the pedal? You're
an engineer and you're saying that in practice you can't avoid eddy
currents. So HOW has Tesla done it?

That's weird because Tesla supply the cars with regenerative braking.
Can you have it removed as an after market option?

To be honest, I know nothing about electric cars but I thought that I
read something about them generating power when coasting that served
to partially top up their batteries.

https://www.greencarreports.com/news...car-completely
Apparently the Tesla does exactly that.
--
Cheers,

John B.

AMuzi wrote:
On 11/17/2020 11:42 AM, Tom Kunich wrote:
On Tuesday, November 17, 2020 at 9:27:11 AM UTC-8, AMuzi wrote:
On 11/17/2020 11:02 AM, Tom Kunich wrote:
On Tuesday, November 17, 2020 at 8:54:15 AM UTC-8, Frank Krygowski wrote:
On 11/17/2020 11:45 AM, Tom Kunich wrote:
On Monday, November 16, 2020 at 11:14:15 AM UTC-8, Frank Krygowski wrote:
On 11/16/2020 1:55 PM, Tom Kunich wrote:
On Monday, November 16, 2020 at 9:31:59 AM UTC-8, Frank Krygowski wrote:
On 11/16/2020 11:36 AM, Tom Kunich wrote:

Unless you're drawing current from generator hubs they shouldn't
be offering any drag at all. They have no friction surfaces and like all
generators only offer resistance when they are in use.
"Shouldn't be offering any drag at all" is true only in the aspirational
sense. They all have some drag (usually minor) when off, due to eddy
current losses if nothing else. This is documented through many tests by
many different investigators. There are have even been a few models that
have less drag on than off.

Really, Tom, you should do a _little_ study before posting.

--
- Frank Krygowski

Really Frank, you should know that in a properly designed
generator there would be no eddy currents generated unless and
until there was an actual current flow pathway.
You're talking about the difference between theory and practice.

In theory, they're they same. In practice they are not.
Not having use the Shimano generator in a long time I was unaware
that they were improperly designed.
But you have no reluctance about posting, of course.

See https://www.cyclingabout.com/dynamo-...g-lab-testing/ along
with many other articles on the subject.

It seems by your standards, even the best are improperly designed. Could
it be the designers know more than you do?

Tell us Frank, why do you think that Tesla's do not have
regenerative braking or decelerate when you pull your foot off the
pedal? You're an engineer and you're saying that in practice you
can't avoid eddy currents. So HOW has Tesla done it?
Tom is once again babbling away in an attempt at deflection.

Focus, Tom, focus! You said bicycle hub dynos have no additional drag
when turned off. You're wrong, as every relevant test has shown.

I'm sure that somewhere in your fantastic resume you have the part where
Elon Musk personally hired you to completely eliminate drag from
coasting Teslas. But that's not what we were talking about.

Just admit you were wrong (yet again) and stop typing.

You were asked a question and you speak of me deflecting? If a dyno
hub has drag when no current is being drawn, it has been improperly
designed. Could I design one that works without drag? Yes, it is NOT
very difficult. You separate the magnets from the conductors when it
is not in use. But you didn't even know that did you? Instead you
blabber on as the all knowing freak of nature you consider yourself.

Spin one in your fingers, no wire.
There's bearing drag and an eddy current.
The distance that magnets are away from the conducting surface and the
how strong a conductor it is makes a large difference. The easy way of
avoiding eddy currents is to move the magnets out of range of the
conductors when you turn it off. From the pictures of the insides of
that generator hub it does not appear that would be an easy thing to
achieve with that design. But just as you shift hub gears you could do
the same thing with a generator hub.



Do I understand you? I think you said that if someone were
to completely redesign the bottle dynamos, fully unlike the
standard format worldwide since the mid-1920s, the eddy
current might be reduced?

Uh, OK. That was helpful...

Any Great Thoughts on bearing drag?


Aren’t the magnets on the part that swirls around in circles? That would
make moving them in and out rather interesting.

news18 wrote:
On Tue, 17 Nov 2020 13:20:57 -0800, Tom Kunich wrote:

I had a hub generator when I was touring but that was more than 20 years
ago and my memory is now shot from that concussion. It is possible to
make very much better generators today since we now have "super magnets"
which weren't available before. Real super capacitors do not exist yet
but I suppose using large capacitors they can even out the ripple from a
DC Generator.

Super magnets would just require more work to overcome the eddy effect.
IME, bicycle Dyno hubs are NOT DC generators. They are AC generators.
Putting AC into a capacitor does not accumulate charge on the capacitor.
It requires some form of rectification, like a capacitor.The historical
trick was finding a suitable diode that didn't let out the magic smoke
going down a good hill, versus doesn't reduce the voltage output too
much.



Synchronous rectification using FETs and a controller is the bees knees.
Schottky diodes are pretty good. Another innovative solution is to just
double the number of LEDs in your lamp and wire them in anti parallel pairs
so you can just run AC straight into it.

Tom Kunich writes:

On Tuesday, November 17, 2020 at 8:54:15 AM UTC-8, Frank Krygowski wrote:
On 11/17/2020 11:45 AM, Tom Kunich wrote:
On Monday, November 16, 2020 at 11:14:15 AM UTC-8, Frank Krygowski wrote:
On 11/16/2020 1:55 PM, Tom Kunich wrote:
On Monday, November 16, 2020 at 9:31:59 AM UTC-8, Frank Krygowski wrote:
On 11/16/2020 11:36 AM, Tom Kunich wrote:

Unless you're drawing current from generator hubs they
shouldn't be offering any drag at all. They have no friction
surfaces and like all generators only offer resistance when
they are in use.
"Shouldn't be offering any drag at all" is true only in the aspirational
sense. They all have some drag (usually minor) when off, due to eddy
current losses if nothing else. This is documented through many tests by
many different investigators. There are have even been a few models that
have less drag on than off.

Really, Tom, you should do a _little_ study before posting.

--
- Frank Krygowski

Really Frank, you should know that in a properly designed
generator there would be no eddy currents generated unless and
until there was an actual current flow pathway.
You're talking about the difference between theory and practice.

In theory, they're they same. In practice they are not.
Not having use the Shimano generator in a long time I was
unaware that they were improperly designed.
But you have no reluctance about posting, of course.

See https://www.cyclingabout.com/dynamo-...g-lab-testing/ along
with many other articles on the subject.

It seems by your standards, even the best are improperly designed. Could
it be the designers know more than you do?

Tell us Frank, why do you think that Tesla's do not have
regenerative braking or decelerate when you pull your foot off the
pedal? You're an engineer and you're saying that in practice you
can't avoid eddy currents. So HOW has Tesla done it?
Tom is once again babbling away in an attempt at deflection.

Focus, Tom, focus! You said bicycle hub dynos have no additional drag
when turned off. You're wrong, as every relevant test has shown.

I'm sure that somewhere in your fantastic resume you have the part where
Elon Musk personally hired you to completely eliminate drag from
coasting Teslas. But that's not what we were talking about.

Just admit you were wrong (yet again) and stop typing.

You were asked a question and you speak of me deflecting? If a dyno
hub has drag when no current is being drawn, it has been improperly
designed. Could I design one that works without drag? Yes, it is NOT
very difficult. You separate the magnets from the conductors when it
is not in use. But you didn't even know that did you? Instead you
blabber on as the all knowing freak of nature you consider yourself.

Every hub generator that I have seen have strong magnetic detents,
they feel notchy when you turn them. You do get some of the energy you
put into going up the hump back on the way down, but because of magnetic
hyesteresis ("iron losses") you don't get it all back.

You could eliminate the detents by using both a wound stator and rotor,
but then you would need brushes or fancy electronics, and everything
would be bigger and heavier and more fragile and less efficient when
actually in use.

The other energy sucking problem that you really can't get around is
"windage", or internal aerodynamic drag. I can't think of any likely
way of eliminating that when a hub generator is switched off, without
fiendish mechanical complexity.

On Wed, 18 Nov 2020 02:11:59 +0000, Ralph Barone wrote:

news18 wrote:
On Tue, 17 Nov 2020 13:20:57 -0800, Tom Kunich wrote:

I had a hub generator when I was touring but that was more than 20
years ago and my memory is now shot from that concussion. It is
possible to make very much better generators today since we now have
"super magnets"
which weren't available before. Real super capacitors do not exist
yet but I suppose using large capacitors they can even out the ripple
from a DC Generator.

Super magnets would just require more work to overcome the eddy effect.
IME, bicycle Dyno hubs are NOT DC generators. They are AC generators.
Putting AC into a capacitor does not accumulate charge on the
capacitor.
It requires some form of rectification, like a capacitor.The
historical trick was finding a suitable diode that didn't let out the
magic smoke going down a good hill, versus doesn't reduce the voltage
output too much.



Synchronous rectification using FETs and a controller is the bees knees.
Schottky diodes are pretty good. Another innovative solution is to just
double the number of LEDs in your lamp and wire them in anti parallel
pairs so you can just run AC straight into it.

Yep, you've got all tat now. Back when I was fiddling around, there
wasn't any corner electronics shops and consumer 'eectroncs' were mostly
luggable. At best, you might get a rare good one by scrapping stuff.

On 11/17/2020 5:56 PM, Mark J. wrote:
On 11/17/2020 10:48 AM, Frank Krygowski wrote:
On 11/17/2020 1:11 PM, Tom Kunich wrote:
On Tuesday, November 17, 2020 at 10:01:22 AM UTC-8, Mark J. wrote:
On 11/17/2020 9:26 AM, AMuzi wrote:
On 11/17/2020 11:02 AM, Tom Kunich wrote:
On Tuesday, November 17, 2020 at 8:54:15 AM UTC-8, Frank Krygowski
wrote:
On 11/17/2020 11:45 AM, Tom Kunich wrote:
On Monday, November 16, 2020 at 11:14:15 AM UTC-8, Frank Krygowski
wrote:
On 11/16/2020 1:55 PM, Tom Kunich wrote:
On Monday, November 16, 2020 at 9:31:59 AM UTC-8, Frank Krygowski
wrote:
On 11/16/2020 11:36 AM, Tom Kunich wrote:

Unless you're drawing current from generator hubs they
shouldn't
be offering any drag at all. They have no friction surfaces and
like all generators only offer resistance when they are in use.
"Shouldn't be offering any drag at all" is true only in the
aspirational
sense. They all have some drag (usually minor) when off, due
to eddy
current losses if nothing else. This is documented through many
tests by
many different investigators. There are have even been a few
models that
have less drag on than off.

Really, Tom, you should do a _little_ study before posting.

--
- Frank Krygowski

Really Frank, you should know that in a properly designed
generator there would be no eddy currents generated unless and
until there was an actual current flow pathway.
You're talking about the difference between theory and practice.

In theory, they're they same. In practice they are not.
Not having use the Shimano generator in a long time I was unaware
that they were improperly designed.
But you have no reluctance about posting, of course.

See https://www.cyclingabout.com/dynamo-...g-lab-testing/
along
with many other articles on the subject.

It seems by your standards, even the best are improperly designed.
Could
it be the designers know more than you do?

Tell us Frank, why do you think that Tesla's do not have
regenerative braking or decelerate when you pull your foot off the
pedal? You're an engineer and you're saying that in practice you
can't avoid eddy currents. So HOW has Tesla done it?
Tom is once again babbling away in an attempt at deflection.

Focus, Tom, focus! You said bicycle hub dynos have no additional
drag
when turned off. You're wrong, as every relevant test has shown.

I'm sure that somewhere in your fantastic resume you have the
part where
Elon Musk personally hired you to completely eliminate drag from
coasting Teslas. But that's not what we were talking about.

Just admit you were wrong (yet again) and stop typing.

You were asked a question and you speak of me deflecting? If a dyno
hub has drag when no current is being drawn, it has been improperly
designed. Could I design one that works without drag? Yes, it is NOT
very difficult. You separate the magnets from the conductors when it
is not in use. But you didn't even know that did you? Instead you
blabber on as the all knowing freak of nature you consider yourself.


Spin one in your fingers, no wire.
There's bearing drag and an eddy current.
While I agree with Frank completely and know that Tom is just
completely
wrong on this thread...

Spinning modern dynamo hubs with fingers at the axle *greatly*
exaggerates their drag. Take the same wheel and spin it mounted to a
frame. It will spin far longer than one would expect from the
finger-axle-spin test.

I *think* what is going on is that the dynamo greatly resists motion
for
some small fraction of a turn *then* propels the axle forward a similar
small distance. The ?stator? ?rotor? nearly "snaps" from one position
to the next. On *average*, over a full rotation, there's only a small
drag, but nowhere near as much as one feels during that first small bit
of twisting the axle.

Finally, not all hub dynamos are created equal, as the drag tests that
Frank cites clearly show. Some have pretty much the same drag with
light on as light off(!) (I think older/cheaper Shimanos fall in this
category), the good ones don't. I'll give a gratuitous plug for SP
dynamos as being among the best in this regard; I own two.

Mark, how much of that resistance is because of the brushes? Since
the poles of a DC motor (from memory) are laminated iron sheet
specifically to prevent eddy currents you wouldn't expect them to be
much of a problem would you? I would expect the brushes to be the
problem and not the eddy currents.

Oh good grief, such technical ignorance!

Hub dynos and other bike dynos don't have brushes because they don't
need them. The magnets rotate. The coils that deliver the output are
stationary and are directly connected to the output wiring. The dynos
put out AC current. There is no need for a commutator to convert it to
DC, and if there were such a need, these days it would be done with
electronics, not brushes.

Sheesh!

What Frank said.

I built an electric motor out of enamel wire, nails, a bent steel bar, a
wood base, cloth "electrical tape," and lots of fussing in ?5th? grade
following a design in the ?Boy Scout manual? or something like that,
even though I wasn't a Boy Scout.

Getting the "brushes" to work was a real fussy bit.Â* Better to leave
them out of your design if you can.Â* Since it didn't have a permanent
magnet, I gather it could NOT(?) be operated as a generator.

As it turned out, the 1.5V "dry cell" battery I had wasn't enough to
spin this kludge job, so we tested it with the family car's battery and
it spun and sparked.Â* As Dad said, "there's no substitute for
horsepower" -- or voltage.Â* But I couldn't take that battery to the
science fair, so no demonstration there, and no prize.

I later pulled a brushless AC induction motor out of a broken ?record
player?.Â* No physical contact between the rotor and wiring, just
?non-conductive? contact at the rotor bearing between rotor and
magnet/body.Â* And the rotor was copper - a non-magnetic metal.Â* Couldn't
understand how it worked until college physics (guess that makes me a
snooty elite college boy) but it was impressive to me.

Thank Mr. Tesla!


--
- Frank Krygowski