Firefly Generator

B

BretCahill

Guest
The "Firefly" sells in bicycle shops for about $8.00. It's an LED + watch
battery that attaches to the rim ends of spokes and creates a pretty noticeable
marker or running light.

The problem is the battery runs down.

Couldn't a small coil + rectifier + capacitor + LED be placed on the spoke ends
with a magnet on the forks or chain or seat stays? The wheel itself would
become a generator.

What kind of small coil would averaget 3 volts/0.1 amp when swiped with a
magnet at speeds > 5 mph?


Bret Cahill
 
In article <20030921234550.17988.00000792@mb-m24.aol.com>,
bretcahill@aol.com mentioned...
The "Firefly" sells in bicycle shops for about $8.00. It's an LED + watch
battery that attaches to the rim ends of spokes and creates a pretty noticeable
marker or running light.

The problem is the battery runs down.

Couldn't a small coil + rectifier + capacitor + LED be placed on the spoke ends
with a magnet on the forks or chain or seat stays? The wheel itself would
become a generator.

What kind of small coil would averaget 3 volts/0.1 amp when swiped with a
magnet at speeds > 5 mph?
Click to expand...
It could be similar to these.
http://www.foreverflashlight.com/

But I think a pair of AAA cells would be much better than button
cells, and would last for months.

Bret Cahill
Click to expand...

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###Got a Question about ELECTRONICS? Check HERE First:###
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Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
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Watson A.Name - "Watt Sun" <alondra101@hotmail.com> in
Message-id: <MPG.19d81a708ecb2c2a9896e1@news.dslextreme.com> writes:
Click to expand...
.. . .

It could be similar to these.
http://www.foreverflashlight.com/
Click to expand...
If the magnet must pass through the coil
it may not work.


Bret Cahill



All conservatism is based on censorship of
economic information.
-- Bret Cahill
 
"BretCahill" <bretcahill@aol.com> wrote in message
news:20030922193916.29959.00000049@mb-m13.aol.com...
Watson A.Name - "Watt Sun" <alondra101@hotmail.com> in
Message-id: <MPG.19d81a708ecb2c2a9896e1@news.dslextreme.com> writes:

It could be similar to these.
http://www.foreverflashlight.com/

If the magnet must pass through the coil
it may not work.


Bret Cahill
Click to expand...
Perhaps you could use a magnet to attract a bit of steel fixed to a piezo
crystal? As the magnet goes past the steel plate it would stretch or
conpress the crystal slightly then let it go. Probably quite inefficient
though!.
 
Hi Bret:

I ride a bike every day and my experience is that the alignment of parts in
affordable bikes is willy-nilly at best. Set up some strong magnets on the
wheel and some induction coils on the fork and it might work; for a while.
The average biker (pedal power type) would probably rather buy batteries
than keep a generator version working. I alreadty have enough trouble
keeping the brakes and the shifter working. The shifter on my bike has a
mind of its own, by the way. I think it's haunted.
 
"Charles Schuler" <charleschuler@comcast.net> in
Message-id: <aS6dnRu5cbP2VO2iU-KYvQ@comcast.com> writes:

Hi Bret:

I ride a bike every day and my experience is that the alignment of parts in
affordable bikes is willy-nilly at best.
Click to expand...
Cheap bikes are OK. Cyclists just need
to stop pegging curbs and start replacing
broken spokes.

Set up some strong magnets on the
wheel and some induction coils on the fork and it might work;
Click to expand...
I understand they already did that for a
head light. I figured a bunch of magnets
would weight more than a coil.

.. . .

The shifter on my bike has a
mind of its own, by the way.
Click to expand...
What makes you think YOUR choice of a
gear ratio is correct?


Bret Cahill
 
In article <20030922193916.29959.00000049@mb-m13.aol.com>,
bretcahill@aol.com mentioned...
Watson A.Name - "Watt Sun" <alondra101@hotmail.com> in
Message-id: <MPG.19d81a708ecb2c2a9896e1@news.dslextreme.com> writes:

. . .

It could be similar to these.
http://www.foreverflashlight.com/

If the magnet must pass through the coil
it may not work.
Click to expand...
The coil is wound flattened out so that it is more like the pancake
coil in a metal detector. Then the magnet passing close by will
generate current.

Bret Cahill
Click to expand...

--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@
 
Watson A.Name - "Watt Sun" <alondra101@hotmail.com> in
Message-id: <MPG.19dad58182ec8be59896fa@news.dslextreme.com> writes:
Click to expand...
.. . .

The coil is wound flattened out so that it is more like the pancake
coil in a metal detector. Then the magnet passing close by will
generate current.
Click to expand...
THAT'S what I wanted to know.

I remembered the definition of some unit
like amp being a unit of magnetic field
passing a meter of wire in the normal
direction at some distance so I should
have been able optimize the coil on my
own. It just took a few tries to articulate
the question.

I'm trying to get away from coffee.


Bret Cahill
 
I figured a bunch of magnets would weight more than a coil.
Click to expand...
Reminds me of a VERY old article from Hot Rod Magazine
where they needed a lot of rotational inertia when they engaged the
clutch
so they put in a _bronze_ flywheel.

Relative densities of iron and copper:
http://216.239.53.104/search?q=cache:rTD_ls9BCLEJ:www.wikipedia.org/wiki/Density+density+copper+8.92&hl=en&lr=lang_en&ie=UTF-8
 
In article <f8b945bc.0309250013.5dc8817f@posting.google.com>,
jeffm_@email.com mentioned...
I figured a bunch of magnets would weight more than a coil.

Reminds me of a VERY old article from Hot Rod Magazine
where they needed a lot of rotational inertia when they engaged the
clutch
so they put in a _bronze_ flywheel.

Relative densities of iron and copper:
http://216.239.53.104/search?q=cache:rTD_ls9BCLEJ:www.wikipedia.org/wiki/Density+density+copper+8.92&hl=en&lr=lang_en&ie=UTF-8
Click to expand...
I drove a deuce-and-a-half truck when I was in Germany in the army.
Flat out in 5th gear, at about 2800 or 3000 RPM, the diesel engine
would do about 65 MPH on the autobahn. Well, that wasn't good enough
for a couple of motorpool grease monkeys, so they disabled the
governor on the engine. The flywheel disintegrated and killed one and
cut the legs off the other guy. Tsk-tsk.


--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@
 
jeffm_@email.com (JeffM) in
Message-id: <f8b945bc.0309250013.5dc8817f@posting.google.com> writes:

I figured a bunch of magnets would weight more than a coil.

Reminds me of a VERY old article from Hot Rod Magazine
where they needed a lot of rotational inertia when they engaged the
clutch
so they put in a _bronze_ flywheel.
Click to expand...
They were probably looking for a way to
save up some energy for a quick start.

A lot of angular momentum in a bicycle
wheel, however, makes me nervous on
descents.

Even worse are low speeds. Overcoming
the inertia will destroy your knees. You
can't just coast through intersections.


Bret Cahill
 
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