100 LED homebrew to share.

Got 100 of the hkled 50,000mcd lights, built a custom circuit board. Put in a regulator, and 8 NIMH AA batteries. Brightness rivals the HID, so I sold my HID lights...100 led matrix album

Interesting...

Stuart

Way to go. I mt bike also but just use a 1 watt Lux headlamp [always on] and a Lux 5 flashlight [for downhills, or when I'm going fast] on the handlebars. That thing looks like it will put out a LOT of light. What kind of runtime do you get on the 8 AAs?

Beamshots???


I always wanted a cluster LED light with around 50 Nichia CS U bin all driven at 20ma and fully regulated. Run it with 6 or 8 AA NIMH cells and it would one of the most impressive lights of all time.

Hmm how abouta 100 5 watt cree or luxeon k2 at about 7 watts in an 700 watt led and 500 watt led. Mmmm.

I no longer have anything to compare it to, so I can't deliver beamshots. Trust me -- it rocks. The quick and dirty way to build one is to get a 100 led light, take out the guts, and regulate it. 8AA NIMH runs for about 3 hours. Doesn't have the throw of the HID's, but the trail is so nicely illuminated. I also built a 200 LED version which is quite nice as well...

Very, very nice!

dang!, we need a cree xr-e version immediately!

Well done,

I'm experimenting with cutting a 10mm led head off, and then using that for a lens on a cree xre. I have also built a 6 led matrix of cree xre with each led driven at 350ma -- that is pretty cool, but too floody.

Thats nice... so this 128 LED flashlight (http://www.dealextreme.com/details.dx/sku.1205) could be pretty bright when using the 50,000mcd leds i guess? (Any maybe even brighter with AA sized lithium-ions :naughty: Well, or it will smoke the led's )

I have the 128 LED light, and unregulated with a ton of AA's, it's pretty bright.... Plus the LED board is much easier to remove from the unit which makes it nice to mod. There's plenty of room in there if you want to mod it to be regulated. 2.5A current regulation would be pretty sweet....

I've built a few lights now using those (the 5mm hkled 50,000 mcds, and also the 10mm hkled 125k mcds)... of course the ratings are exaggerated, but as tested elsewhere here and other sites, they are some of the brightest LEDs in their categories nonetheless.

Anyhow, they make great bikelights, I've got beamshots compared to other lights (halogens, maglights, mag/LED upgrades, other LED flashlights, etc) (but they stink as my camera is not great in dim lighting), the results I've seen running the 5mm LEDs around 25ma each, the "apparent" ratio of LEDs to halogen lights are 20x5mm LEDS = 1x10watt/6V halogen. They are whiter, with a little less spill than the halogen (but a much smoother transition, the halogen spill is wider, but useless near the edges).
So for power, you've got 20x25mAx3.6Vf = 1.8 watts of LEDs for 10 watts of halogen (of course the 20 LEDs take up slightly mroe space and require some circuitry, so it's not all about the power savings, but...)
Given that a 10-watt HID is roughly equivalent to a 35 watt halogen, you would need around 35/10*1.8 = 6.3 watts of these LEDs (at 25mA/3.6V approximately). So finally, that gives us around 70 LEDs to equal an HID.
So bottom line, in my informal testing (of about 5 LED fixtures compared to several bikelight options), the observation that a 100-LED array of the hkled units definitely should be "visibly" brighter than a 10-watt HID. Of course it's a fairly large (in frontal area) unit compared to a compact HID bulb, so you have to get over the clunkiness factor (same problem on my larger handlebar units, my helmet lights are nice round 20-LED units though).
For whoever asked about runtime, I don't know what current he's running his array at, but at a modestly overdriven 25mA, it's easy enough to do the math, 100*.025*3.6V (approximate at that current) = 9 watts. Converting (for simplicity's sake) to a strictly parallel array (it's the same whether parallel or serial, but easier to match battery ratings in parallel)), it's 100*.025A = 2.5A of draw, so on a 2.5A source at matched voltage, you are looking at 1 hour runtime, etc. (Add a 20% penalty for regulator/circuit losses for more realistic figures).

Looking at these another way, each LED at rated 20mA is around 4.5 lumens output in the 2 or 3 ratings estimates I've seen on them. Overdrive them a little and say 5 lumens. A 10-watt HID is typically around 450-500 lumens, so again the math works out (but the tighter beam of these LEDs is more usable in some respects than HID (brighter in middle, less spill beam, smooth transition), so they seem a bit brighter still than the total luminosity would indicate (unless you want a particularly wide beam, in which case the HID may seem a little more useful).

Anyhow, they are fun (and cheap as dirt, relatively) to play with, the key drawback of course is surface area, as pictured in the original poster's model, 100 LEDs even very compact (overly so it seems) take up a substantial surface area. Also, heat in that packed an array could be a real problem, so LED life is going to be affected (unless underdriven to start with)... the problem I've had in some of my 40-LED "box" lights with much more surface area and cooling than what appears available above, is they've gotten pretty warm in usage (regulator and LED heat)... so packing 100 into around the same area, in a THIN package, yikes, those don't have much of a heat sink to dissipate away from the LEDs.
Other than that heat concern, nice design! (At $29/100 or whatever they are today, if they die, put more in/build a new one, LOL).

I've stopped using them simply because it's easier to put a few Cree XR-Es together for the same output in a much more manageable footprint. A single Cree XR-E at 700mA (*3.3V = with a Ledil lens in a 1"x1.5" package with a substantial copper mounting heatsinked to the aluminum body is about the same output as a 25-LED hkled package, but with much better thermal management and the tiny relative footprint. 3 or 4 together would easily beat the 100x5mm in output, in a 50mm diameter package (much smaller still than the larger array), at the same or less power consumption. Of course they cost more (at an average of say $10/emitter-mounting combination plus $8 per lens, that'd be $72 in LED parts alone), so there is that drawback.

I custom ordered the hkleds in that array to not have a flange at the base. The matrix is 50mmX50mm, plus a little excess. Cooling is uniquely accomplished by the construction technique.

Quick question, I have read that those hkled's have horrible tint and beam patterns. with all of them mixing together, how is the color? Do you think you could post up a shot of the light illuminating your yard maybe. I am thinking of ordering these lights but I don't want them to have really bad tint.

Also, it seems they have been replaced with 55,000mcd leds. Does anyone have any experience with these? Thanks

A 40mm CPU fan on the back of that array should keep it cool.