LED bicycle light confusion

[Hellion Darklord]

Sorry for posting this in the wrong location the first time!  I really didn't intend to!  

This is my first post ever.  I would like to know how to go about making a LED light for my bike.  I have thought about making it from dozens of LED lights.  What I want is to place as many white LEDs as close together as possible and be able to turn on only as many as I want at one time.  If I can use some kind of POT to do this it would be GREAT! and if not I have ideas for something else that would be a little bulky, but still do the trick.

I have really no idea what I'm doing.  I think I want to make the LEDs sit in a round housing if possible.  I think it would make sense to have the LEDs aranged so that the center LED sticks further forward than the ring of LEDs around it and the ring around the center LED set further forward than the next larger ring. The reason I would do this is to spread some light out to the sides and also make the light more visible to others.  I think that the light from the outside LEDs will reflect a little off the sides of the center LEDs.  Does this make a little sense or is this totally wacky?  I want to be able to pack the LEDs as tightly as possible. Would supergluing them together make them get too hot?  Do they even get hot?

Is it possible to use one BIG resistor instead of a big cluster of small ones?  It would be nice to keep weight as low as possible.  I am thinking about drilling holes into a cone of solid rubber or trying to find something that I can just poke the leads through that will retain a nice cone shape and be easily molded yet non-conductive. I'm hoping that with a 12.5w battery from this old light http://www.cygolite.com/2-Products/10-Night%20Rover-2%20in%201.gif  I will be able to make a light that shines brighter than the headlights on a car and last longer than 1 hour on high.

Also, I think I will use this LED... http://www.superbrightleds.com/specs/W18030.htm it is around $50.oo for 50 LEDs. Is there a brighter more efficient LED out there? this one is 5mm but it looks to me like it has good output, so I will allow for a little bit of bulk as long as this thing will be bright like daylight. (I'm still afraid of the dark... especially at night!)

If one LED puts out 18000 MCD will two alike LEDs put out 32000 MCD?  900,000 MCD with 50 LEDs seems bright enough don't you think? If so I think I can get pretty bright with the battery I have.  The battery is supposed to last at the very least 3 hours running at 6 watts. 50 LEDs would run with a lot less than 6watts right?

Well I have so many danged questions I don't know what to do with myself, so I think I'll go to bed and try to worry about the 6 to 8 hour night rides (with that pretty blonde I'm drooling over) I want endure tomorrow.  I can't seem like some kind of looser who is afraid of the dark infront of her, now can I?

And remember, an exponent is a phonological manifestation of a morphosyntactic property

Hellion

[Hellion Darklord]

sorry, I thought that the urls would be clickable in the post.

[Marco]

I looked into LED's a while back, (my commute is 16.5 miles each way for a total 2.5 hours on the road max.

1. LED's are generally good for being seen by drivers but no to see the road ahead.
   
2. Ultrabright LED floodlight systems are starting to appear now but are hugely expensive, so it would make more sense to go down the road of HID lamps. (Cateye stadium, lumicycle HID etc..
   
3. But I suspect you like to home build. Here is what I did (check out my website) on the cheap with willie Hunt's LVR3 (thats lightbulb voltage regulator) Google it.
   
   

I get high beamed by cars sometimes!!

Marco

[Volvo farmer]

Tom Woods has exactly what you're looking for in kit form. I built one a while back and posted about it here. Look at the discussion for a little info about MCD and for Tom's website.

Check the Hong Kong sellers on Ebay for cheap ultra bright LEDs. Both Tom and I have bought from them with good luck.

I've never taken mine outside at night to check but Marco had a good point. I would guess this thing might be as bright as a AA maglite. A three D cell maglite would be much brighter than the LED lightboard I built.

http://www.fieldlines.com/story/2005/4/5/04059/61832

[BT Humble]

I looked into LED's a while back, (my commute is 16.5 miles each way for a total 2.5 hours on the road max.

Wow, you're tougher than me!  I have 10km (~6mi) each way, and I'm usually getting pretty tired by Friday.

Of course, since it's a relatively short distance I don't spare the ponies. ;-)

BTH

[kita]

not LED but maybe relevant?

http://www.ladyada.net/make/bikelite/index.html

[fungus]

You can get LEDs off ebay much cheaper, last time I looked it was £4-5 for 100.

[ghurd]

Often you get what you pay for.

[gotwind]

The best, not the cheapest LED lights are made by cateye in the U.S

http://www.cateye.com/uk/products/viewProductModels.php?catId=7&subCatId=2

I have used these with my dynohub projects at gotwind.org

http://gotwind.org/circuit.htm

[pemtek]

If your going to mess about with white LED's just buy a single LED that will perform better than your 50 cheap chinese 5mm devices.

Trying to connect 50 separate LED's, house them, get rid of the heat and align them wont be fun!

The most common of the power LED's are the Luxeon products they range from 1 > 5.6 watts for a single LED and if you order the STAR type they have a nice little aluminium pad that can be used to glue or bolt the device to a heatsink. The newest they sell is called the K2 but are just becoming available and produce around 40 lumens per watts maximum at low currents, although this will drop massively as your push the device harder max continous is 1.5Amps.

The most efficient (efficatious) LED currently is the CREE Xlamp it is similar to the Luxeon with a lower power rating. The current 1 watt Xlamp will give out more light than the Luxeon 3 watt part! It produces a wopping 46 lumens per watt driven an around 60 lumens at its rated 350mA.

Osram do some good LED's the best being the OSTAR which is a monster 14watt part! but the price is prohibitive. They do a RGB version destined for mobile phone and mini projectors. The more affordable part is the

There are many similar devices and some nice chinese copies and similars but some are quite useless.

If you look about there is also a nice selection of optics available for the various LED's many can be found on ebay.

I pay £2.20 for a Luxeon 3 device and about £2 for an Xlamp but some shops sell them for upto £13!!!!

If your using a single LED you dont want to be using 12v as the power source or you will be loosing 2/3+ of the power as heat unless you use a switcher. 6v would be a better choice.

If you want any help with a simple circuit to drive them / it just ask

Phil > sorry for babbling!