Bulb or not Bulb for led lighting ?

[yveslafont]

Sorry if my english is bad, i'am french ^^

Incandescent and CFL lights have a large emitting radius ..
A "360 degree" led bulb does have multiple led emitters, well disposed, and the heat is a real problem when the power is more of 3 W.
As for incan or halogen, le direct light hurt the eyes.

I build some leds lights on aluminium "L" "U" "T" and double "U" rails.
With indirect lighting, on white reflection surfaces, the light is very smooth and hightly selective.

350 ma is a bit low, only 100 lm on a Xr-e led
700 ma cause some heat problems, so i use often 500 ma, not very used, but a nice compromise with heat and lumens, looking on the technical curves.

With a "L" aluminium rail ( a few euros for 2 meter length / a few bucks for 80 inches), 35 mm x 35 mm x 2mm, i can place one 500 ma xr-e led every 8 cm, the heat on alu keep less as 25 °C after 6 hours, and the chip temperature is around 50 °C (is use infrared thermometer).
I use Arctic Alumina under the led, and silicone glue around to lock the led.
I'am tried some 12v and ac 220v drivers, to have the best efficiency.

So, it is very versatile for me to create some lights, on walls, or hidden.

I will post some pics later about this little projects.

 

[blasterman]

Welcome to the club of DIY ligtbars. Several of us have been using alu bar for projects, and refining or projects bit by bit.

The advantages of building lights this way are numerous and covered in your post. Materials are readily available and cheap, we can choose preferred emitters and power supplies, and thermal management is a breeze. Our custom bars will easily out-last most commercial options. Plus, I get my metal from a local shop that buys aluminum extruded by a local mill, and it's cheap. I also prefer to run 3-watt emitters at around 500mA because it's seems a sweet spot when it comes to magaging heat -vs- light.

Lately I've settled on C-channel; 1 inch high by 1-1/2" wide. This allows the emitters to be hidden inside the channel where optics become an option and not a necessity. Plus, it's stiff and can be hung or suspended. Running bare it's easy to achieve over 100 lumens per watt. I've also started to cover my bars with strained wood to give it a professional look, which you can see in my picture below.

Only thing I'm trying to figure out is diffusion. Even with wide optics LEDs are a very specular light source that isn't appealing in all situations. I'm trying to find a material that can be suspended below the light bar and do a good job diffusing the LED light as a possible add-on option.

 

[jason 77]

Blasterman, I've been reading up on a product called "whiteoptics" it seems like it could be a good way of blending or to defuse the light given off from LEDs. I have been unable to find a place to buy the raw material though :mecry:

http://whiteoptics.com/White97%20Film%20data%20sheet.pdf

 

[blasterman]

Same here. There are some high tech 'micro lenticular' plastics on the market as well they are supposed to do the job, but can't find them. Basically, it's the same material used on emitter optics to give wider diffusion, but in sheet form. I've tried window films that emulate frosted glass, but they didn't work. I'm looking ACRYLITE® Crystal Ice next.

 

[AnAppleSnail]

I'm planning a similar design to see how building my own LED lights goes. I was going to use an AC to DC constant-current power supply, but sourcing that part fell through. In its absence, I'm running a laptop power supply to a HipCC driver running 2 strings of XREs to get 500-1000 mA per LED (Changing the power levels of the driver will slightly dim the set). It's not the most efficient, but it'll work without throwing another $50 out. Are there better ways to do this (Cheap AC to DC power safe for LEDs)?

 

[jason 77]

I'm planning a similar design to see how building my own LED lights goes. I was going to use an AC to DC constant-current power supply, but sourcing that part fell through. In its absence, I'm running a laptop power supply to a HipCC driver running 2 strings of XREs to get 500-1000 mA per LED (Changing the power levels of the driver will slightly dim the set). It's not the most efficient, but it'll work without throwing another $50 out. Are there better ways to do this (Cheap AC to DC power safe for LEDs)?

Yeah I have been trying to get away from using laptop power bricks... I have a ton of them I got from my old work.

I found this site a few weeks ago, I haven't actually ordered anything from them but they have AC/DC power supplies that are the cheapest I have yet seen.

12VDC 1.8 amps 85-264VAC in all for $19.51 USD!

http://www.trcelectronics.com/Meanwell/nfm-20-12.shtml

 

[blasterman]

I have a crate full of HP laptop bricks I got on surplus. At 18.5 volts they are perfect for 3-watt emitters - 5 per series. I generally use them for testing, and then get a dedicated driver when I figure out what I'm doing.

Right now Mean Well is dominating the driver market with high durability and inexpensive drivers. Most have variable voltage ranges as well so you can tweak your out-put. The current regulated versions cost a bit more, but if you plot your series voltages properly you can get away with fixed voltages. No need for resistors if you can just trim the voltage a bit.

Check out Jameco for these.

 

[yveslafont]

Thank you very much Blasterman, for your nice work !

i'am trying some parts from broken flat tft displays, some acrylic sheets into with fresnel effect, and crackled hard panel.
You are right, the led spot is not easy to look.
500 ma is a nice compromise for current, 350 ma get too few lumens, ans 700 ma provide some heat problems.

500 ma is hard to find in avalaible drivers, so i use 1 000 ma drivers in two chains in parrallel.

Sorry for this late feedback, but no many time this weeks ^^
Grettings to all, CPF is a very very nice forum

 

[blasterman]

Right now finding efficient, cheap and nice looking methods of LED diffusion are my main goal. Power and intensity is no longer an issue given the availability of Bridgelux coupled with Mean Well drivers, but we still have the same nagging issue: bare LEDs make rather lousy interiour light sources.

I'm looking at plastics like ACRYLITE Crystal Ice for potential diffusion given frosted glass is a pain to work with. I tried window films that emulate frosted glass, and only had mediocre success.

Right now I've got a cool design I'm finishing up that bounces the LEDs off a 6' high white panel. Should have that finished up in a few weeks.

 

[yveslafont]

Did you read about Edison Ediline 3 séries ?
I work with 1w and 3,5 W models in warm white, 80 lm/w at 350 ma,
light is rectangular and provide very large angle, less shadows than rail of stars ...

Blasterman, about your projects, how much % you loose in luminosity versus a bare led ?

 

[yveslafont]

Prismatic Acrylic Sheet
Find something about "perspex" acrylic sheets :


"Prismatic acrylic sheet is a textured acrylic sheet often used as a light diffuser in fluorescent light fittings or similar applications."

Found too LSD products, here is sample request form : www . luminitco . com / node / 62 (remove blanks)

 

[blasterman]

I've seen the Edison's and have been curious about them. Been wanting to build some bare LED rails with them and see how they look. However, because of their shape optical options are pretty limited. They have nice efficiency though. Bridgelux tends to suck in this department although they have high dollar / lumen ratios.

Going through acrylic is about a 5-10% penalty depending on how diffuse it is. There are some micro-lenticular difusion panels on the market designed for LED that are supposed to be 95% efficient, but they are high volume only. I assume these are the same materials snapped onto LED optics that provide higher degrees of diffusion.

Right now I'm working on a simple bounce style lamp. The light penalty is much higher, but bouncing gives you the highest degree of diffusion. However, rather than bounce off a ceiling, I'm going to move the diffusion source lower and make it part of the lamp.

 

[Dave_H]

but we still have the same nagging issue: bare LEDs make rather lousy interiour light sources.

A humble observation, the light from a cheap ZhongSheng 1W
flashlight star, operated with the head and reflector removed,
is amazingly diffuse, almost up to 180 degrees. It looks like
chip-on-board with a blob of epoxy, probably not very optically
efficient. Problem is it is not very bright, and I have no idea of
expected lifetime (short, most likely). The thing doesn't seem
to get more than warm on continuous use, so maybe this technique
has some merit...

Dave

 

[bshanahan14rulz]

Right now I'm working on a simple bounce style lamp. The light penalty is much higher, but bouncing gives you the highest degree of diffusion. However, rather than bounce off a ceiling, I'm going to move the diffusion source lower and make it part of the lamp.

There are quite a lot of artsy hoity toity new-age fluorescent fixtures that do this exactly. Perhaps you could retrofit one of your aluminum c-channel bars you already have into these types of fixtures.

 

[blasterman]

There are quite a lot of artsy hoity toity new-age fluorescent fixtures that do this exactly.

Eh....most don't do it well though, but I know what you mean.

Years ago when I rented a condo with vaulted ceilings I tried everything to light that room decently. There were no recessed cans (thank god) not that I would have used them anyways. A lot of torche' style lamps were perhaps the best option, but when that's the only light source it becomes rather vague and ambiguous as main light. Most of the commercial fluorescent 'bounce' fixtures I've seen that I believe you are referring to are the same way.

So, being a tight budget, I took a spare 48 white photographic umbrella, put it on a light 8' light stand, and bounced a couple of CFLs on book shelf clamps into it. The light turned out to be pretty amazing and not only filled the room, but had some localized direct light as well. Cheap, bright, and looked damn good. Even impressed the chicks I was dating

I've been trying to emulate that lamp with LEDs ever since. Originally I was going to build something with bi-pin / quad-pin and take advantage of the external ballast and higher quality bulbs, but reflectors are a pain. The advantage with LED is that they are already directional.

Yep, C-channel firing upwards with a long white strip over the top bouncing down would look cool as well. This would be something more akin to a desk or task lamp, and be an obvious solution for the new Crees. you could also mix some different colors in there and get some uber_high CRI levels as well.

 

[kaichu dento]

Eh....most don't do it well though, but I know what you mean.

Years ago when I rented a condo with vaulted ceilings I tried everything to light that room decently. There were no recessed cans (thank god) not that I would have used them anyways. A lot of torche' style lamps were perhaps the best option, but when that's the only light source it becomes rather vague and ambiguous as main light. Most of the commercial fluorescent 'bounce' fixtures I've seen that I believe you are referring to are the same way.

So, being a tight budget, I took a spare 48 white photographic umbrella, put it on a light 8' light stand, and bounced a couple of CFLs on book shelf clamps into it. The light turned out to be pretty amazing and not only filled the room, but had some localized direct light as well. Cheap, bright, and looked damn good. Even impressed the chicks I was dating

I've been trying to emulate that lamp with LEDs ever since. Originally I was going to build something with bi-pin / quad-pin and take advantage of the external ballast and higher quality bulbs, but reflectors are a pain. The advantage with LED is that they are already directional.

Yep, C-channel firing upwards with a long white strip over the top bouncing down would look cool as well. This would be something more akin to a desk or task lamp, and be an obvious solution for the new Crees. you could also mix some different colors in there and get some uber_high CRI levels as well.

I can't wait to see what you come up with and you've already got me thinking about getting a photographic umbrella now.

 

[MrTea]

Jason77 - I can provide you directly with a WhiteOptics sample sheet for your project - contact me at [email protected]

 

[csshih]

wow... cpf , bringing manufacturers with customers