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Shakin' Fake Flashlights

P

Paul E. Schoen

Jan 1, 1970
0
I bought a motion-powered flashlight from a Chinese vendor at a flea market
in Harpers Ferry last year. It was only about $2, and it had a fairly
bright blue/white LED that came on when I turned the switch. I could see
that there were two coin cell batteries inside, but there was also a coil
through which a magnet would pass when the light was shaken, and a little
PC board connected to the coil. It appeared that the light got brighter
when I shook it. I used it for a while, and I misplaced it.

I returned to the flea market last Sunday, and they had what appeared to be
the same flashlight, three for $5. So I bought three of them, along with
other things. When I got home and looked more carefully, I saw that the PC
board was not populated. I took the light apart, and found that (1) the
leads from the coil were tied together to one point on the board, and (2)
what I thought was a magnet was just a slug of steel. The lights actually
work fairly well, and not too bad a price for a disposable LED flashlight
and wrist exerciser (if I decided to shake it).

They had other flashlights for about $4 that seemed to have a larger
battery pack, and possibly a PC board with components. I'm sure there are
some of these lights that actually work, but I don't know if this vendor
sells them. They are probably all fakes. They do have some dual LED hand
powered lights for $4 that work by squeezing a lever which operates a small
clockwork dynamo, and they function properly. They also have an internal
battery and a switch in case your hand gets tired. Probably the gears will
soon wear out and it will also become a disposable flashlight, but it is
amazing what you can get for a few dollars.

I do wonder what it takes to make a good hand powered light using a sliding
magnet and coil. It would probably take several hundred turns of wire to
get 3 to 4 volts for a white LED. You would probably need diodes to get DC
for the LED, and they would need to be Schottkey or Germanium for
efficiency. It might be necessary to have a capacitor or inductor to smooth
out the pulses from the coil. There is probably an optimal coil design to
get the most usable output from the variable motion of the magnet.

Maybe I'll try a Google search, but I am curious if anyone knows any more
about these devices. Also, maybe some ideas on how I can get even with
these vendors of fakes!

Paul
 
M

Mike Harrison

Jan 1, 1970
0
I bought a motion-powered flashlight from a Chinese vendor at a flea market
in Harpers Ferry last year. It was only about $2, and it had a fairly
bright blue/white LED that came on when I turned the switch. I could see
that there were two coin cell batteries inside, but there was also a coil
through which a magnet would pass when the light was shaken, and a little
PC board connected to the coil. It appeared that the light got brighter
when I shook it. I used it for a while, and I misplaced it.

I returned to the flea market last Sunday, and they had what appeared to be
the same flashlight, three for $5. So I bought three of them, along with
other things. When I got home and looked more carefully, I saw that the PC
board was not populated. I took the light apart, and found that (1) the
leads from the coil were tied together to one point on the board, and (2)
what I thought was a magnet was just a slug of steel. The lights actually
work fairly well, and not too bad a price for a disposable LED flashlight
and wrist exerciser (if I decided to shake it).

They had other flashlights for about $4 that seemed to have a larger
battery pack, and possibly a PC board with components. I'm sure there are
some of these lights that actually work, but I don't know if this vendor
sells them. They are probably all fakes. They do have some dual LED hand
powered lights for $4 that work by squeezing a lever which operates a small
clockwork dynamo, and they function properly. They also have an internal
battery and a switch in case your hand gets tired. Probably the gears will
soon wear out and it will also become a disposable flashlight, but it is
amazing what you can get for a few dollars.

I do wonder what it takes to make a good hand powered light using a sliding
magnet and coil. It would probably take several hundred turns of wire to
get 3 to 4 volts for a white LED. You would probably need diodes to get DC
for the LED, and they would need to be Schottkey or Germanium for
efficiency. It might be necessary to have a capacitor or inductor to smooth
out the pulses from the coil. There is probably an optimal coil design to
get the most usable output from the variable motion of the magnet.

Maybe I'll try a Google search, but I am curious if anyone knows any more
about these devices. Also, maybe some ideas on how I can get even with
these vendors of fakes!

Paul

I got one which did include a 0.1F supercapacitor etc. to make it work 'properly', but also had 2
lithium cells..!

You can tell the really good ones, as instead of the rubber bumpers at the ends of the tube, they
have additional magnets to repel the main one, preserving the energy at the end of the stroke
instead of turning it into heat. You can easily 'feel' the difference - the good ones feel 'springy'
instead of thumping at the end of the travel.
These ones are good : http://www.edi-t.com/index0.htm
 
A

Ancient_Hacker

Jan 1, 1970
0
Paul said:
I bought a motion-powered flashlight from a Chinese vendor at a flea market
in Harpers Ferry last year. It was only about $2, and it had a fairly
bright blue/white LED that came on when I turned the switch. I could see
that there were two coin cell batteries inside, but there was also a coil
through which a magnet would pass when the light was shaken, and a little
PC board connected to the coil. It appeared that the light got brighter
when I shook it. I used it for a while, and I misplaced it.

Watch out-- I got one of these flashlights for xmas. Very interesting
insides. A quick peek and my dubiousness-meter pinned. The coil had
about 40 turns of wire on it. The PC board had NO components on it.
Opening it up, the moving "magnet" turned out to be non-magnetic.

I guess what happens is if the factory runs out of supercapacitors or
diodes or runs low on coil wire, they switch over to making "fake"
flashlights. Well, they're flashlights all right, but "shake to
charge" in looks only.

If you look closely at the pictures of these flashlights on eBay, a
good 20% of them have no parts on the PC board. Hard to rectify and
store shake energy without rectifiers or capacitors.
 
R

Rene Tschaggelar

Jan 1, 1970
0
Paul said:
I bought a motion-powered flashlight from a Chinese vendor at a flea market
in Harpers Ferry last year. It was only about $2, and it had a fairly
bright blue/white LED that came on when I turned the switch. I could see
that there were two coin cell batteries inside, but there was also a coil
through which a magnet would pass when the light was shaken, and a little
PC board connected to the coil. It appeared that the light got brighter
when I shook it. I used it for a while, and I misplaced it.
[snip]

I got one from a fleamarkey too. It had the components
and it worked, still works. While the clear plastic
case allows to follow the magnet and have a look at the
coil, I would have appreciated if they made a sheed
of iron to the outside. The field is rather strong,
and I wouldn't recommedn to have it beside a floppy
for example. A sheet of iron would have increased the
magnetic flux and thus the efficieny.

Rene
 
M

mc

Jan 1, 1970
0
Watch out-- I got one of these flashlights for xmas. Very interesting
insides. A quick peek and my dubiousness-meter pinned. The coil had
about 40 turns of wire on it. The PC board had NO components on it.
Opening it up, the moving "magnet" turned out to be non-magnetic.

I guess what happens is if the factory runs out of supercapacitors or
diodes or runs low on coil wire, they switch over to making "fake"
flashlights. Well, they're flashlights all right, but "shake to
charge" in looks only.

If you look closely at the pictures of these flashlights on eBay, a
good 20% of them have no parts on the PC board. Hard to rectify and
store shake energy without rectifiers or capacitors.

Now I'm going to go take a good look at mine...

Isn't this a matter for the Federal Trade Commission? Some importer is
going to get busted.
 
M

Michael Black

Jan 1, 1970
0
Ancient_Hacker" ([email protected]) said:
Watch out-- I got one of these flashlights for xmas. Very interesting
insides. A quick peek and my dubiousness-meter pinned. The coil had
about 40 turns of wire on it. The PC board had NO components on it.
Opening it up, the moving "magnet" turned out to be non-magnetic.

I guess what happens is if the factory runs out of supercapacitors or
diodes or runs low on coil wire, they switch over to making "fake"
flashlights. Well, they're flashlights all right, but "shake to
charge" in looks only.

If you look closely at the pictures of these flashlights on eBay, a
good 20% of them have no parts on the PC board. Hard to rectify and
store shake energy without rectifiers or capacitors.
I have one of the LED flashlights that has a crank to turn that charges
a battery. It's still doing fine after a year and a half, and it would
be an odd application where I couldn't stop to crank it rather than
simply shake a shaking flashlight. It is more expensive than the
shaking flashlights being talked about. And it's not as bright as
the LED adaptor I bought for my Maglite.

ON the other hand, I once bought an LED flashlight that was in a package
similar to the cheap laser pointers, and when the batteries ran out (the
switch kept activating while in my pocket), I just bought a $1.99 laser
pointer and used the batteries from that. It seemed cheaper than
buying batteries separately (and I have the laser pointer to run from
an external supply if I ever get around it). Actually, the laser pointers
turned out to use the same batteries as a number of items I have around, so
they become a good source of batteries.

Michael
 
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