LED Flashlight--Off topic

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Reply to
Nick Hull
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Yes, and 90 mAh is about 3% of the capacity of a lithium AA.

I still like the little reed switch you found better, though. That's how I'm go>D>

Reply to
Don Foreman

That would be very annoying in use. I'd rather have it dim or possibly use a small red LED at very low power as a low battery indicator.

Ted

Reply to
Ted Edwards

Or maybe have the white one extinguish, and turn on a red one instead - where the red one has a lower draw, but will continue to stay lit when the white one would be out.

Jim

Reply to
jim rozen

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.

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.

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.

Polished hardened steel former, silver sheet + big hammer.

2cm^2 of silver sheet is cheap.
Reply to
Ian Stirling

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.

Reply to
Ian Stirling

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)

Reply to
Ian Stirling

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

Jim

Reply to
jim rozen

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

Reply to
Ian Stirling

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

Keep us posted on your progress, please!

Reply to
Don Foreman

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.

Reply to
Ian Stirling

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

Jim

Reply to
jim rozen

Simichrome polish works great for that.

That's a good way to go.

Jim

Reply to
jim rozen

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.

Reply to
Ian Stirling

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

Reply to
dbs__usenet

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

Reply to
ERich10983

I want one!! When are you selling it?

Reply to
Nick Hull

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.

Reply to
Ian Stirling

Thanks for the reference, Earle.

Jim

Reply to
jim rozen

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

Reply to
Harold & Susan Vordos

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