LED Flashlight--Off topic
 

Don Foreman wrote:
On 16 Nov 2004 23:45:27 GMT, Ian Stirling
wrote:

The reteroreflector lets you shrink the size, while retaining beam
quality.

True if "beam quality" means maximum collimation for long "throw",

It does.

The reflector will be movable, so that in combination with altered
reflectivity (either white or shiny, I'm unsure which is best) of the
inside, you can go from various different beam shapes, from a tight
beam, to a wide flood.

It was the only possible solution for reterofitting a mini-maglite solitare.

With a conventional parabola, you lose a lot of the light out the front,
with most designs, meaning you don't get a nice sharp beam, but a lot of
light goes round the edges.

So an unconventional parabola would be better? What sort of
unconventional parabola might that be? Unconventional focal length
perhaps. The trick in a retro is to match the reflector to the
feed's radiation pattern so the feed port doesn't block the beam.

Err, no.
I was referring to the fact that a parabola with a light source at the
focus is conventional for lights.
You need to go to a very large parabola to reduce the amount of light
going to the sides.
If you put a lens in front of the parabola, then you can fix that, but
it's then got to be some other shape.

I played with this using the radiation pattern of a white Luxeon
side-shooter emitter with the constraint of reflecting nearly all
emitted light in the beam while blocking nearly none with the emitter
in the retro path. Math model. Found a minimum exit aperture and
focal length of truncated paraboloid of revolution to make it so.

The side-shooter isn't really ideal, because you get (AIUI) two
different places that the light comes from, the front reflector, and
the direct radiation. This makes focusing a problem.

You're surely well past my primitive level of understanding, but I
found it fun to explore. Question for you, pls: how will you
make and then reflectorize your reflectors?

Polished hardened steel former, silver sheet + big hammer.

2cm^2 of silver sheet is cheap.

Don Foreman wrote:
On 16 Nov 2004 23:49:22 GMT, Ian Stirling
wrote:



Micros are so cheap low power and small nowadays, that even running them
all the time on an AA cell will not noticably degrade the shelf life for
many technologies. (lithium excluded)

You needn't exclude lithium in that assertion.

It depends.
A 20 year life (retaining 50% capacity is quite likely).
Say 3000mAh for a Lithium AA cell, that's 75mAh a year, to in addition
drain it completely.
So, say 30mAh a year, or 3uA.
Many micros will use much higher currents than this, especially including
a voltage conversion.

Nick Hull wrote:
And I know I'd prefer a lamp that went dim, or otherwise indicated
imminent failure, rather than one that just went out.

Why not design a LED flashlight that flickers when the batteries get low?

The one I'm planning (if the user does not switch modes) goes at 100% to
33% battery, then 50% to 25%, and then drops down to 10% till 10%, at
which point it goes to 1%.

So, it carries on producing light for about 15 times what it would normally
do, but the step tells you how much power you've got left.
Turn it on at 30% battery life, and you get a bright flash, and it then
goes dimmer.

Turn it on at 5% life, and you get a bright flash, followed by rapidly
dimming 3 times.

(it can be switched at any point to the maximum power that the battery
will support)

In article , Ian Stirling
says...

Polished hardened steel former, silver sheet + big hammer.

2cm^2 of silver sheet is cheap.

Doesn't the silver tarnish rapidly? I would think you would
be better of with aluminum.

Jim


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jim rozen wrote:
In article , Ian Stirling
says...

Polished hardened steel former, silver sheet + big hammer.

2cm^2 of silver sheet is cheap.

Doesn't the silver tarnish rapidly? I would think you would
be better of with aluminum.

It's good enough for prototypes.
Aluminium is much harder to polish to a mirror finish, and really wants
to be vacuum deposited.

On 19 Nov 2004 16:28:53 GMT, Ian Stirling
wrote:

So your sapphire lens will be a refractor as well as a heatsink?

Keep us posted on your progress, please!



Polished hardened steel former, silver sheet + big hammer.

2cm^2 of silver sheet is cheap.

Don Foreman wrote:
On 19 Nov 2004 16:28:53 GMT, Ian Stirling
wrote:

So your sapphire lens will be a refractor as well as a heatsink?

No, it's just a planar window.
I can just about deal with slicing a bit off a boule to get a nice flattish
slice, and then machining it to diameter and polishing.
Figuring into a lens would be a bit more than I can do.

In article , Ian Stirling
says...

Don Foreman wrote:
On 19 Nov 2004 16:28:53 GMT, Ian Stirling
wrote:

So your sapphire lens will be a refractor as well as a heatsink?

No, it's just a planar window.
I can just about deal with slicing a bit off a boule to get a nice flattish
slice, and then machining it to diameter and polishing.
Figuring into a lens would be a bit more than I can do.

Way too much work, just order the thickness and diameter of
a polished wafer from either Saphikon or Meller Optics.

Jim


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In article , Ian Stirling
says...

Aluminium is much harder to polish to a mirror finish,

Simichrome polish works great for that.

and really wants
to be vacuum deposited.

That's a good way to go.

Jim


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please reply to:
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==================================================

jim rozen wrote:
In article , Ian Stirling
says...

Don Foreman wrote:
On 19 Nov 2004 16:28:53 GMT, Ian Stirling
wrote:

So your sapphire lens will be a refractor as well as a heatsink?

No, it's just a planar window.
I can just about deal with slicing a bit off a boule to get a nice flattish
slice, and then machining it to diameter and polishing.
Figuring into a lens would be a bit more than I can do.

Way too much work, just order the thickness and diameter of
a polished wafer from either Saphikon or Meller Optics.

I can chop and polish a wafer for about $30 in materials. (if I diddn't
have most already)
And then $1 for the next 10.

Don Foreman wrote:

Please keep us posted on your progress in making one that is even
better. Your use of a sapphire lens as a heatsink is interesting.
I don't see much advantage in a retroreflector, but one issue I had
with that concept was heat transfer which your scheme neatly solves.
Streamlight, I think, offers the "recoil" which is a retroreflector
but I wonder how or if they accomplish heatsinking without fragility.


It's Pelcan that makes the M8 and 2020 Sabrelight. They call it the
'recoil' system.

They use a cheaper lens and mount the LED on an aluminum support. The LED
is only running at 1 watt, so there's not a lot of heat to dissipate.
The support is thin but deep, so it can support the LED and conduct the
heat away.

The pelican recoil lights are made for diving and rescue work where
there is smoke or silt to obscure your vision. Light that spreads out
will reflect off the silt (or smoke) causing glare caled backscatter
that make it harder to see. The recoil beam is so concentrated that
it illuminates an 18 inch by 18 inch square at 15 feet with virtually
no light outside that square. Yes, I have one in my collection.

Optics are another way to concetrate the light without having a large
reflector. There are many makers of optics just for LED lights.
I have a 10 degree optic on the light in my pocket. It's only 17 mm
across and less than that deep. If the retroreflector does not pan out,
optics may be the answer.

Daniel

No, it's just a planar window.
I can just about deal with slicing a bit off a boule to get a nice flattish
slice, and then machining it to diameter and polishing.
Figuring into a lens would be a bit more than I can do.

Way too much work, just order the thickness and diameter of
a polished wafer from either Saphikon or Meller Optics.

Saphikon was purchased by Saint Gobain, a French conglomerate similar to
General Electric. The new company name is Saint Gobain Crystals, still located
in the same place in MIlford, New Hampshire. (603 673 5831). I used to work for
them but didn't survive the semiconductor industry collapse. Not a big deal
since I've really been enjoying retirement.

Earle Rich
Mont Vernon, NH

In article ,
Ian Stirling wrote:

Nick Hull wrote:
And I know I'd prefer a lamp that went dim, or otherwise indicated
imminent failure, rather than one that just went out.

Why not design a LED flashlight that flickers when the batteries get low?

The one I'm planning (if the user does not switch modes) goes at 100% to
33% battery, then 50% to 25%, and then drops down to 10% till 10%, at
which point it goes to 1%.

So, it carries on producing light for about 15 times what it would normally
do, but the step tells you how much power you've got left.
Turn it on at 30% battery life, and you get a bright flash, and it then
goes dimmer.

Turn it on at 5% life, and you get a bright flash, followed by rapidly
dimming 3 times.

(it can be switched at any point to the maximum power that the battery
will support)

I want one!! When are you selling it?

--
Free men own guns, slaves don't
www.geocities.com/CapitolHill/5357/

Nick Hull wrote:
In article ,
Ian Stirling wrote:

Nick Hull wrote:
And I know I'd prefer a lamp that went dim, or otherwise indicated
imminent failure, rather than one that just went out.

Why not design a LED flashlight that flickers when the batteries get low?

The one I'm planning (if the user does not switch modes) goes at 100% to
33% battery, then 50% to 25%, and then drops down to 10% till 10%, at
which point it goes to 1%.

So, it carries on producing light for about 15 times what it would normally
do, but the step tells you how much power you've got left.
Turn it on at 30% battery life, and you get a bright flash, and it then
goes dimmer.

Turn it on at 5% life, and you get a bright flash, followed by rapidly
dimming 3 times.

(it can be switched at any point to the maximum power that the battery
will support)

I want one!! When are you selling it?

I've got to make a prototype first! :)
Then I might think about it.
It would be a relatively premium price device (though I'd hope not
significantly so), but I'm considering including stuff that is relatively
inexpensive to add, but would add utility.
For example, a backup zinc-air battery would add about 5mm to the length
of the torch, and provide 30 hours of light at about the same intensity
as 1/4 a normal LED.

In article , ERich10983 says...

Saphikon was purchased by Saint Gobain, a French conglomerate similar to
General Electric. The new company name is Saint Gobain Crystals, still located
in the same place in MIlford, New Hampshire. (603 673 5831). I used to work for
them but didn't survive the semiconductor industry collapse. Not a big deal
since I've really been enjoying retirement.

Thanks for the reference, Earle.

Jim


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"ERich10983" wrote in message
...
snip------
I used to work for
them but didn't survive the semiconductor industry collapse. Not a big
deal
since I've really been enjoying retirement.

Earle Rich


Earle,
Some time ago I recall that you were offering induction power supplies for
the hauling. Is it safe to assume you were employed by them at that time,
and have since gone into retirement?

Like you, I've enjoyed my retirement, which I took just before I turned 55.
Being self employed, it was just a matter of making a decision to do so.
My only regret thus far is that I didn't make that decision earlier.

Harold