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bike lights

Making some bike lights for my daughter who rides her bicycle in traffic in Brooklyn NY.

I'm playing with some red Luxeon LED's, powered from 3 NiMH rechargable penlight cells.

These suckers are seriously bright. I noted that the one I was running looked yellow (not red) from a distance of 100 feet -- but when I looked away for a bit and then looked back they looked red agan for an instant. WTF, over?

When I walked back I noted that the spill on the table looked red. Geez, maybe I overloaded my red receptors?

I turned down the current to 30% by soldering in another dropping resistor. Sure enough, it then looked red at 100 feet.

Wondering why everything looks green now.......

Reply to
Don Foreman
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So, what were you doing in the '60s and '70s? Consequences of early life-choices?

Reply to
Tom Gardner

Reply to
Don Foreman

Update:

I found some small trailer marker lights at Northern Tool for about 2 bux. I bought one to cut apart for the lens. The Luxeons I bought are Lambertian emitters. Their radiation pattern is more like a small filament bulb than a conventional LED. I therefore thought perhaps a lens devised for use with a small filament bulb might work well.

It does.

The red Luxeon behind that lens is noticable even in direct sunlight.

I tried it tonight with two 60-watt patio lights and two 100-watt PAR floods illuminating the backyard to provide some competition like citylight in Brooklyn will provide. I walked back 100 feet to check it out from there.

Uh...wow. I think this dog will hunt.

Reply to
Don Foreman

Nice report, Don! Thanx. Do you know if the manufacturers have data books out yet on the new hi-power leds?

Reply to
Robert Swinney

Don't know about books, but datasheets on the Luxeon's are available for download. The one I'm using is at

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There are also 3-watt and 5-watt versions.

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Jerry and I each made pretty awesome flashlights with 3-watt white Luxeons.

I prefer to buy the bare emitters rather than the "stars" and machine (METAL CONTENT) little studs that I epoxy them to with Omegabond epoxy. I can get them further into a reflector that way.

Osram also offers some bright LED's. Digi-Key even carries them. They're not as bright as the Luxeons, but a couple of them are close.

These LED's are really fun to play with!

Reply to
Don Foreman

Is there something special about Omegabond compared to other epoxies?

Ted

Reply to
Ted Edwards

What's that Lassie? You say that Don Foreman fell down the old rec.crafts.metalworking mine and will die if we don't mount a rescue by Tue, 07 Sep 2004 16:58:57 -0500:

Lots of good stuff about LED flashlights here:

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Reply to
dan

Reply to
Don Foreman

Any idea what the filler is? Aluminum powder maybe?

Ted

Reply to
Ted Edwards

Reply to
Don Foreman

In some cases (emerson and cummings 2850 epoxy) the filler is aluminum oxide powder - sapphire. They also make a

1299 epoxy with quartz microspheres as the filler.

I guess if I were doing this and needed high thermal conductivity I would go with EpoTech's silver-filled epoxy, like the H20S. Nice stuff.

Jim

Reply to
jim rozen

Reply to
Don Foreman

Right. I mentioned it as an example of a really high thermal conductive adhesive. Obviously it will short out whatever electrical contacts is covers.

Jim

Reply to
jim rozen

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