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View Full Version : Cheap LED's vs A Little Homebrew (Geek Alert)



Novakane
05-19-08, 12:19 AM
I'm still not 100% sold on LED's, although I admit I've not had the chance to play with some of the new super-bright LED's. However, I've been using a cheap Raleigh branded light I bought a few years ago as some basic "please see me coming" light, with a slight visibility increase. It uses 5 bright LED's with lenses molded into one.

http://blogtroll.misanthropy.info/bicycle/light_raleigh.jpg

When I went camping last summer I brought (with a slight idea of testing...) a light I bought at the local Dollarama. Designed as a basic flood (brand is Home Luminaire, package suggests for home, camping, workshop, car) this light employs three surprisingly bright LED's and performed as a decent flashlight for getting around. I can't complain for $1 and three AAA batteries.

http://blogtroll.misanthropy.info/bicycle/light_dollarama.jpg

So, I think to myself - I was able to get a fair amount of light from one of these, so what would happen if I stuck one on a bicycle? The idea was fleeting for a time, seeing as I was walking at a slow pace in near absolute darkness - no way it would be adequate for speeds over 2-3kph, I'm sure. I can't see myself riding at that speed and not feeling like I was doing an extended track stand.

However, the idea formed in my mind that if I combined several of these, I'd have more light, right? I'm no physicist, but I know the basics of electronics. I figure, the best way to find out is just to try. I mean, at $1 per three LED's, it's a pretty cheap gamble.

The ultimate goal was to combine four of the lights into one. Thus far, after an evening of hacking, a bottle of wine and some rye, I managed to find a simple way to combine three. The last one will have to wait.

I pulled out my weapons of mass construction (soldering iron, glue gun, utility knife and a tube of silicon for good measure) and started to mess around. After removing the first few LED's I realized that they had very short leads. I feared this would be the case. However, in my random bits and pieces collection I had some 16-pin IC sockets. I was able to stick eight LED's into this, forming two rows of four (I had to scrape a little plastic off the round side of the LED's to make them fit snug.)
I also tested some resistors I had on hand and they significantly dimmed the light, so I decided to use the one inside the original lights. For testing purposes I realized it was easiest to just connect my contraption to one of the built in LED connectors.

This is what it looks like (in no way mountable to bike right now, I admit):

http://blogtroll.misanthropy.info/bicycle/light_test.jpg

So how does it work? Well - head on it hurts the eyes to look at:

http://blogtroll.misanthropy.info/bicycle/light_bright.jpg

I found that without a lens to focus it that it provides a much larger flood than the Raleigh light can. However, the hot-spot in the middle of the Raleigh is indeed brighter. This brings me to the problem I have with the Raleigh. All five LED's have a different focus and it produces a very annoying dark spot between each which makes it unreliable for night riding. There's one bright beam in the middle, but the focus is narrow and the other four just split away to the sides and top dimly, so I find myself fiddling with the light every time I change terrain / grade.

Since I'm using my phone camera to take these pics, I won't waste anyone's time taking a night shot, it doesn't handle them well in the best of conditions. I must say, I was a little disappointed. The Raleigh still proved the brighter light. The real charm is when I combine them though - the Raleigh's blind spots get filled with a bright white flood, providing a light I think would be adequate for night riding. Not quite as good as the halogen's I've been messing with, but certainly better than either LED system on it's own.

I plan to take the remaining four LED's and putting them in pairs above and below the eight shown to make a rough cross pattern and form something more circular.

Next up - something to work as a lens to focus the beam. I'm thinking about the center cut out of one of those flexible magnifying sheets, adjusted for the desired beam distance... Not sure if that's going to work or just be a pipe dream.

Final Summary:

The commercially made Raleigh light beats my Home Brew light as a spot, hands down - the opposite is true in terms of a flood. Solution - combine both and get a usable system.

Novakane
05-19-08, 01:50 AM
As a slight follow up, I cut a hole in the upper face and back of a cat-eye front (clear) reflector the size of the IC socket and glued my hack into it, then mounted it to the front of my commuter bike. I taped the switch / battery system up on top of it. Not very elegant, and totally exposed to the elements. It's raining pretty heavy out, so I guess I won't get to test it outside of the basement - but so far, it's looking like a promising flood light. If this works well, I'll clean it all up and take some pictures.

n4zou
05-19-08, 08:01 AM
You've done an admiral job hacking a few cheap lights and combining them into a nice "see me" light. It's obvious your skills are good enough to go for a truly bright DIY LED headlight. You'll want to look at all the neat stuff available at these two sites.
http://www.dealextreme.com/ click on the Flashlights/lamps link then DIY parts and tools.
http://www.kaidomain.com/WEBUI/Default.aspx click on sports/hobby's then flashlights-diy

I like Fraen LED optics available here. http://www.luxeonstar.com/
Fraen optics are much better than the optics sold at dealextreme and kaidomain.

The Fraen optics for everything except the K2 will fit the CREE and SSC LED's available at dealextreme and kaidoman.
Here is a photo of my light with the cover removed so you can see two SSC P4 U-BIN LED's sitting under two different Fraen lenses and holders. A 15X30 producing an elliptical beam pattern 15 degrees vertical by 30 degrees horizontal and a 10 degree narrow beam. This is exactly the the light you said you wanted to build in your post.
http://i143.photobucket.com/albums/r154/n4zou/light.jpg

Here is the light mounted on my touring bike.
http://i143.photobucket.com/albums/r154/n4zou/HPIM0395.jpg

I power my light with a bottle type dynamo so no batteries are ever required.
http://i143.photobucket.com/albums/r154/n4zou/Hpim0329.jpg

Here is a link that shows how to build your own battery or dynamo powered bicycle lights using high power LED's.
http://pilom.com/BicycleElectronics/BicycleElectronics.htm