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View Full Version : LED lighting, no longer a novelty



Evan
05-23-2009, 06:00 AM
I have been experimenting with LED lighting for some time now. Up until recently most LED lighting has been more decorative than truly functional. That's about to change. It will only be a short time and you will begin to see LED "light bulbs" that are very satisfactory replacements for incandescent and CFL bulbs.

I recently purchased 3 ultra bright 5 watt emitters to test as a replacement for a small flood light at our back door. This has always been an issue since we like to leave it on but don't want to waste a lot of energy. We would commonly have a 100 watt incandescent and that can add up fast if it is on nearly 24/7 in the winter. CFL bulbs just won't operate at the low temperatures we experience at that time of year.

So, I modified a small cast aluminum floodlight housing that I bought for about $5 some years ago. It was intended to use a 300 watt halogen which was out of the question for this application. I removed the innards and the 117 ac wiring and made a small plate of 1/4" aluminum to fit in the base of the housing as a heat sink on which to mount the diodes.

This is what the emitters look like,
http://ixian.ca/pics6/ledhi1.jpg


The heat sink includes a small sheet of copper clamped to the back side of the aluminum mounting plate. That copper is bent around to conform to the housing side wall and fastened to it to allow the housing to act as a radiator for the waste heat of the diodes.

This is what the flood light looks like with the diodes operating:

http://ixian.ca/pics6/ledhi2.jpg

The diodes are glued to the mounting plate with heat sink glue compound. This makes mounting much easier than using mechanical fasteners.

The power supply is a 1.5 amp 5 volt unregulated wall-wart power supply. It is a perfect match for the three diodes which are wired in parallel. No current limiting was required as the power supply is exactly matched to the load. Each diode draws about .5 amp but can be operated as high as 1 amp at reduced lifetime.

This is a 1 second exposure of the illumination this light provides. This exposure is subjectively very close to how it appears to the eye, power consumption about 15 watts. The emitters cost $4.90 each.


http://ixian.ca/pics6/ledhi3.jpg

kmccubbin
05-23-2009, 07:52 AM
Good info! How well would that work for a machine tool lamp? Do these LED's emit a tight beam or a wide flood? I'm needing more illumination for my lathe and mill. Halogens are too hot, and normal LED's aren't quite bright enough to suit me.

Thanks,
Kerry

torchroadster
05-23-2009, 08:05 AM
Very interesting.

Is this what you were using? http://www.theledlight.com/luxeonV_white.html

Where you able to find a better price than $27?

murph64
05-23-2009, 08:34 AM
Nice.

I picked up something similar as a replacement "bulb" for my 2D MagLight. Holy smokes is it bright, and the batteries last a LOT longer.


Andy

Evan
05-23-2009, 08:34 AM
$4.90 each from Dealextreme. ( in quantity of three)

http://dealextreme.com/details.dx/sku.4516

It's bright enough that a lamp with about 9 emitters like that would illuminate a small shop decently. I intend to build a few more such lamps because they will run a long time from a UPS.

The emitters are unfocused and provide about a 90 degree beam of light with perfectly even coverage. The color is between warm and cool white, very natural looking.

loosescrewmt
05-23-2009, 09:12 AM
LED lights are also starting to show up in theater/concert settings. My side job is working for a small audio porduction co. and we've talked about getting some of the new led cans for our setup. 1000 w light output w/ far lower current draw. That's a big plus for our situation. Last summer we did an outdoor show, threw the breaker on a 135 kw genset- and we weren't running everything as far as the lights went, just finally pulled enough juice to trip the breaker. (IIRC, the audio end needs about 60 kw for all the amps- this doesn't include the stuff that a band brings with them)

Our lighting guy thinks that we could get 48 lights, our standard outdoor rig, and run them on something like 1\3 the power. Plus, no more color gells, supposedly the leds can do all the colors. It's surprising how much light output is lost when the gells are in place.

Evan
05-23-2009, 09:28 AM
The biggest issue when working with LEDs like this is to provide adequate heat sinking. While they don't produce a great deal of waste heat that heat is concentrated in a very small area. The power density with an emitter like this is unreal. The active area of the 5 watt emitter is only a few square millimetres. That puts the power density up in the range of 100 watts per sq centimetre so proper heat sinking is mandatory.

gnm109
05-23-2009, 10:02 AM
Of course many of the traffic liights in the U.S. have now been converted to LED arrays. They give a much better light at greatly decreased current usage.

I have some of the small ones on my model railroad to show turnout position and for signals that have been running for many years. If the current is limited properly they really don't burn out in normal use.

I think the OP's LED lights would be grrat for a shop. I'm tired of buying 8 foot fouorescents every now and then. I will have to look into them.


.

tony ennis
05-23-2009, 10:20 AM
Evan, what has changed to make these a viable primary lighting source?

Evan
05-23-2009, 10:36 AM
A lot of things are changing very quickly. The main thing is cost. Last year an emitter like this was $20 each. Now it is $5 and by next years they will be down to a buck or two at most. Also, new processes are coming online right now that make it possible to obtain very much better efficiencies. That is absolutely necessary because of the high power density. You can only remove so much heat from a small area without resorting to active methods and that isn't a viable solution for lighting in most cases.

There are units now that can compete directly with incandescent in terms of brightness and have much lower consumption. There are also direct drop in replacements for fluorescent tubes but they are still expensive.

Go to dealextreme.com and search on Cree. Cree is a brand name USA manufacturer of LED emitters headquartered in North Carolina with manufacturing in the US. That's right, you can buy a US made product from Hong Kong cheaper than you can buy it in the USA.

http://www.cree.com/

dp
05-23-2009, 01:08 PM
There are some very interesting LED form factors shown here:

http://www.edison-opto.com.tw/products_inx.asp?category=1

But no prices.

RancherBill
05-23-2009, 01:09 PM
The project is really interesting.

You talked about Deal Extreme in the past. I have been hesitant to order. As you know, the total 'true cost' of importing from the US via UPS has has soured me on the process. USPS is OK.

For the benefit of the Canadian guys, what might we expect in charges when purchasing from DE.

Thanks in advance.

john hobdeclipe
05-23-2009, 01:53 PM
I'm convinced that within the next 5 years, LED technology will render both incandescent and fluorescent lighting obsolete.

I have a couple of workspaces where I do close work (jewelry) that require cool, even lighting. I'm thinking about trying one of these:
http://www.1000bulbs.com/SeeSmart-LED-T8-Tubes/

I recently read of another new development, something having to do with a layer of "quantum dots" over the LED that provides a "warmer" incandescent-like color without sacrificing efficiency.

danlb
05-23-2009, 01:57 PM
Dealextreme often has free shipping, and they routinely mark the package as "gift" and then quote a lower value than reality. This avoids some, but not all, customs hassles.


I've used LED lights on my small lathe (7x12) and micro mill for several years. They perform pretty well. I have older leds that are only 1 watt and about 30 lumens. Modern replacemnts will be 5 times as bright using the same power.

How much is 30 lumens? It uses a reflector, and at 10 inches from the LED it reads the same on my light meter as a 250 wattt halogen 4 feet above my work bench.

If you decide to make one, keep in mind that there is a big difference between the low power LEDs found in the real cheap flash lights and the high power LEDs such as Luxeon, Cree and Seoul. A low power LED is used in lights such as the ones with 22 leds running on 3 aaa batteries. You get 1 to 5 lumens per LED.

Traffic lights use low power LEDs, but they use a lot of them and the light is focused towards the driver.

I highly recommend LEDs. :)

Dan

barts
05-23-2009, 02:04 PM
I bought an LED floodlight at Costco the other week. Not super bright, and rather blue, so I'm using it in the ceiling mounted can in our pantry; it's plenty bright for that and the instant on is perfect. The kids sometimes leave the pantry open, so I didn't want to go back to halogen, and CFL just take too long to turn on.

I think I need to experiment w/ some of these 5W parts...

- Bart

danlb
05-23-2009, 02:11 PM
If the light is supposed to be white but is really rather blue, it means the LEDs are real cheap or (more likely) they are running with too much power. Too much power means they will burn out fairly fast, as little as minutes or as long as years.

BTW, cheaper LEDs will not have the same color "spectrum" as the better ones. This will cause some colors (reds and browns, for instance) to be muted. Not a big deal unless you are looking for collor changes while tempering. It's also a problem when reading resister color codes. :)

Dan

Evan
05-23-2009, 04:08 PM
For the benefit of the Canadian guys, what might we expect in charges when purchasing from DE.


This is my third order from them. Each order has been in the range of $200 total or so. Each order has been ignored by Canada Customs and has come through with no inspection, no GST or duty and no delay. This order arrived 3 working days after it landed in Canada. DX always has free shipping with no minimum order at all. The usual wait if you have ordered a large range of items is 1 to 2 weeks before it ships. If something is backordered they will wait up to two weeks and then ship what they have with the rest to follow and no extra charge of any sort. Their customer service people are efficient and helpful but you must make your communications to them very clear and use 500 word english for best understanding.

lazlo
05-23-2009, 05:25 PM
Go to dealextreme.com and search on Cree. Cree is a brand name USA manufacturer of LED emitters headquartered in North Carolina with manufacturing in the US. That's right, you can buy a US made product from Hong Kong cheaper than you can buy it in the USA.

Those are Chinese LED chips Evan. Cree bought Cotco, a Chinese LED manufacturer based in Hong Kong, in early 2007. All of Cree's consumer product line is now made in the Cotco factory in China.

Dextreme is a Chinese company that drop-ships directly from the manufacturer. Everything they sell is Chinese origin, and comes in a Chinese air mail envelope.

The problem I've had with the Chinese LED's is, as usual, quality. I'm on my second Sears Craftsman LED work lamp. The LED's keep dying en masse after about 10 hours of use. Ditto with a Woodcrafter's magnetic LED work lamp. Fortunately, both companies have excellent return policies.

By the way, Dan's right about the cheap "white" LED's having intense blue light. Almost all "white" LED's are blue InGaN LED's with proprietary phosphor coatings that phase shift the blue to white. The quality Japanese, Korean, and Western LED's are much whiter than the cheap Chinese LED's.

CCWKen
05-23-2009, 06:14 PM
I'm amazed at what's available now. Even in the cheap flashlights. I've got a three AAA-cell LED flashlight that will blast a beam an easy 200'. There's tractor headlights and work lights now that rival the halogens. Still on the pricey side but they're coming down in price. What's great about the work lights is that you can add four or more to the tractor with little load on the existing wiring. They're plenty bright for evening and night work.

Evan
05-23-2009, 08:47 PM
Those are Chinese LED chips Evan. Cree bought Cotco, a Chinese LED manufacturer based in Hong Kong, in early 2007. All of Cree's consumer product line is now made in the Cotco factory in China.

So what are they making at the Durham fab? They sure are expanding based on the number of jobs they have listed. According to the various stories surrounding that merger it's Cotco that buys LEDs from Cree.

http://www.ledsmagazine.com/news/4/3/12

http://www.simplyhired.com/job-id/3wz6qtnknv/process-sustaining-jobs/

Regardless of where they are made they are binned according to the Cree binning guide which guarantees that the product meets specifications that are clearly spelled out regarding brightness and color temperature. Deal Extreme gives the binning for all the Cree parts they sell.

http://www.cree.com/products/pdf/XLamp7090XR-E_B&L.pdf


Everything they sell is Chinese origin, and comes in a Chinese air mail envelope.


Of course it comes in a Chinese envelope. It's shipped from Hong Kong.

Deal Extreme sell more than Chinese made products. They also don't drop ship from the manufacturer as that would be impossible. I bought items from a wide variety of manufacturers so they must package and ship them from their own facility. Deal Extreme does drop ship to wherever you wish and there are companies in the US that resell directly from DX and have DX drop ship for them, usually at very inflated prices.

DX also sells top brand names such as Transcend flash ram.

From a product page


* Lifetime Manufacturer Warranty: The manufacturer Transcend (www.transcendusa.com) offers lifetime warranty on this product. Should the SD card become defective at any point in time, customers should contact Transcend USA directly for repair and replacement.



They also sell quite a few items made in Japan such as Kingston and Nichia.



- Japan version
- Genuine Kingston Product
- Fast data transfer rate
- Write-protect switch with adapter
- Included adapter allows the card to be used in Secure Digital (SD) compatible devices
- Lifetime warranty from Kingston Technology
- Assembled in Japan ("ASSY IN JAPAN" on package, and "JAPAN" printed on card)

http://www.dealextreme.com/details.dx/sku.2396

lazlo
05-23-2009, 09:16 PM
According to the various stories surrounding that merger it's Cotco that buys LEDs from Cree.

http://www.ledsmagazine.com/news/4/3/12

It's not a merger -- Cree bought Cotco (the Chinese LED manufacturer). The title of that article you linked is "Cree buys Chinese LED manufacturer Cotco"



So what are they making at the Durham fab?

The Dunham fab is a SiC & GaN foundry. Cree has an extensive product line of silicon carbine power electronics, RF electronics, milspec electronics, etc. They also outsource their fab for small MIMIC runs.

andy_b
05-23-2009, 11:39 PM
i am going to have to look into these. that spotlight photo is incredible.
how hot does this thing get compared to a 100watt spotlight?

andy b.

Evan
05-24-2009, 12:25 AM
It gets very slightly warm to the touch. The waste heat only amounts to a few watts.

Tobias-B
05-24-2009, 01:44 AM
LED lights are also starting to show up in theater/concert settings

Limited spectrum lighting (florescent, LED, gas- emission, etc)
isn't really going to take over the theatre market-
we start with full spectrum light and then filter out the undesirable colors
to get an almost- unlimited spectrum.
It's horrifically inefficient, to the point where you can have
4- 600 KW shot at an opera set, and you still can't see much...

What might replace it are true Red Green Blue fixtures... but don't
count on it happening any time soon in theatre.

Concerts, it's already happening. LED striplights, LED video panels,
you name it, it's out there. Very cool, very efficient, and it looks great.
Except those blue LED's. I can't look at those.

t

Evan
05-24-2009, 04:16 AM
It's not a merger -- Cree bought Cotco ...

Not a merger?



The deal will provide Cotco's parent company, Cotco Holdings Ltd, with $70 million in cash and 7,604,785 shares of Cree stock valued at $130 million, based on the average price over the previous twenty trading days. Additional consideration of up to $125 million is tied to the Cotco business achieving specific financial targets over the next two fiscal years.

"We are excited about the merging of Cotco into Cree, which will provide Cotco with access to Cree's technology and comprehensive IP resources. This combination will strengthen Cotco's leadership position in the solid-state lighting supply chain," said Paul Lo, Cotco Holdings chairman.

RancherBill
05-25-2009, 12:27 AM
Thanks for the reply Evan.

No warranty expressed or implied. YMMV.

It answers a question I've had for a while.

Do you get commissions at DE? I'll mention your name! :)

Evan
05-25-2009, 12:37 AM
I do believe there is a "recommended by" spot on the order form. If so then put in "JunkMeister". :D

No commission as such but they give DX points good for free stuff.

I moved the light and took a better image last night. You can see by the exposure of the light through the window that it isn't a tricked up image since the inside light is the right brightness.

http://ixian.ca/pics6/led7.jpg

Willy
05-25-2009, 01:07 AM
I do believe there is a "recommended by" spot on the order form. If so then put in "JunkMeister". :D

No commission as such but they give DX points good for free stuff.



Hey Evan, I'll remember that the next time I put in an order with DX.
It's the least we can do for all of the R&D work you are doing for us!

rotate
05-25-2009, 01:19 AM
The diodes are glued to the mounting plate with heat sink glue compound. This makes mounting much easier than using mechanical fasteners.



Is "heat sink glue compound" sort of like conductive 2 part epoxy (containing silver)?

Evan
05-25-2009, 06:09 AM
I used 1 part thermal adhesive that DX sells. It's a white filled paste which means it has one or several ceramic fillers the same as silicone based thermal paste. The adhesive isn't identified but a check on similar compounds indicates that it is most likely a heat activated mono component epoxy. The thermal properties are pretty good.

Something that I have noticed is that the Chinese have become especially good in the field of adhesives. They make excellent cyanoacrylate products, even of the dollar store variety. In the case of this thermal glue I haven't run any quantitative heat transfer tests but it seems to be keeping the diodes well cooled. 7 dollars will buy a tube big enough to mount a few thousand units.

Caution in use is warranted. It's a good idea to keep it off your skin, especially if you are young.

From a MSDS for a similar product:



11. Toxicological Information (continued)

Chronic Health Hazard: Rats exposed to component 2 at 150 ppm for 50 7-hour exposures demonstrated significantly retarded growth. In the same study, there was 50% mortality in rats exposed at 300 ppm, with additional signs of toxicity in the survivors. Testicular atrophy was observed in rats exposed at 300 ppm, but the rats were juvenile, obscuring the significance if any, of the result. In a 28 day inhalation study, rats exposed at 188 ppm showed decreased body weight and changes in blood chemistry. Severe irritation of the upper respiratory tract was observed in rats exposed at 94 ppm and 188 ppm.

Component 2 is N-Butyl Glycidyl Ether, a solvent for the epoxy component.