LED lighting ?

You can probably do it cheaper by ripping apart some of the cheap 'n' cheerful Chinese corn cob bulbs from eBay--the ones JL posted about a month or two back.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 

Yeah, they have aluminum-core PC boards, which will help keep the LEDs cool. Leds get dimmer and die sooner if they get hot.

That's 60 white LEDS for about $5.

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John Larkin         Highland Technology, Inc 

jlarkin at highlandtechnology dot com 

Look at

All sorts of LED lighting + drivers, from full fixtures to individual bits.

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Regards, 

Adrian Jansen           adrianjansen at internode dot on dot net 

I have a few awaiting "time, copious spare" which is about as easy to find as unicorn manure. When I have to place a small order, I look around for other things I might play with to make the shipping cost less painful, and I've bit on a few different LEDs for that. Depending what LED you are looking at, read up on the datasheets to see what the manufacturer suggests for heat dissipation. Some are much easier than others. I've got a variety of old cpu heatsinks (including some eMac heat-pipe units) that seem like they might work for the low-budget junk box approach. Some LEDs that I'm using should work fine with sheet copper connecting to them (two separate pieces, of course.) Others will work with enough area of copper on a fiberglass PCB - much less power density there. I worry less about getting the maximum light from a single LED [leading to the maximum thermal issues], and look more at $ per lumen as well as lumens per watt, including little factors like "this one needs a fancy heat sink for extra $" to try and build a holistic picture of built cost. Still, it's far from mature.

While some LED retrofit bulbs are awful, some are not [I'm not wedded to the idea that it must look exactly like an incandescent bulb, just that the light is good from it and it fits the fixture], and occasionally get down to a price where I'll buy one. Mind you, they are very much a moving target, since what you bought a year or six months ago is usually not available now, but that usually means "nominal improvement." The most recent sub-$10 "40 watt replacement" bulb I got makes 450 lumens from 7 watts, while the previous one is 429 from 9 watts. Those actually seem a bit brighter than a 60W incandescent to my eyes, which is probably a color-temperature effect. They are usually still somewhat less efficient on lumens per watt than fluorescent, but in some applications that is not the most important aspect - in places where the bulb is cold and/or gets switched a lot, CFLs stink (and die young).

Tolerably well constructed LEDs also take a lot more shock than incandescent or CFL. While a more attractive design could be managed [they are lit tips with opaque lower thirds], the 2W LED candelabras I stuffed into the outside porch light have already paid for themselves on electricity, and have also saved at least 5 bulb changes (swinging in the wind is not good for filaments.) That particular fixture is a pain to change bulbs in, so that part even beats the power savings. Of course, by the time I've decided that a test subject has good build quality, I may not be able to buy another just like it, but so far even the oldest test subject is still working.

--
Cats, coffee, chocolate...vices to live by 
Please don't feed the trolls. Killfile and ignore them so they will go away.

ons

ies.

t

Hard to beat $10...

ilver-85-265v-174187

Warm white:

-milky-white-181552

Now, if it'll only not burst into flames!

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Cheers, 
James Arthur

Ok, so forget the "expensive" fixture. Just buy LED light strips (or strip lights) and attach them to the ceiling, under shelves, above doors, and where lighting is needed. The row across the bottom of my LCD monitor isn't very bright, but it puts the light close to where I need it. No fixture needed:

Output for a single row of these LED strips is typically about 60 lumens per foot. It will take about 10ft of the stripping to equal the brightness of a 60 watt "equivalent" screw in LED light. The 4 LED across denser variety will produce about 800 lumens per linear foot, where 1 foot length is about the same as a 60 watt "equivalent" screw in LED light. The denser spacing will probably get quite hot and may need a heat sink. I haven't tried these yet. The single row LED strips get warm, but not hot enough to burn anything.

When you say that the retrofit bulbs are awful, are you referring to the color? It does take some time to get used to LED lighting. I took me about 3 months, the same amount of time it took me to get used to CFL bulbs. I suspect it would also have taken the same amount of time to adjust from candles to kerosene lamps, and from kerosene lamps to Edison incandescent lights. Give yourself some time to adjust. Try to get LED lamps that have a CRI (color rendering index) greater than

85 to be as close to natural light as possible.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 

Seems expensive. I bought 16 feet for $16. I tried it, I like it. Have not installed any yet.

Waiting for some $5 halogen replacements from china. Looks encouraging.

Greg

Running a LED at maximum current will cause light drop quite rapidly in perhaps a few thousand hours.

To obtain claimed tens of thousand hour lifetimes and claimed efficiency above 100 lm/W, you need to run a 350 mA "1 W" LED at

100-200 mA. This also greatly simplifies thermal design.

Of course, you need at least twice the number of LEDs, which makes the project quite expensive.

Jon Elson schrieb:

Hello,

the thermal situation may be okay if the strip of copperclad board is wide enough and there is enough free air flow. It is difficult to calculate before building, but you may measure the temperature very close to the LEDs to see if and how it rises during at least an hour of operation. You should try this not only at normal room temperature but also when it is a very hot day.

Bye

snipped-for-privacy@downunder.com schrieb:

Hello,

there should be some remarks in the data sheet about the measurement conditions used for lifetime and efficency.

Bye

On a sunny day (Wed, 06 Mar 2013 18:05:07 -0600) it happened Jon Elson wrote in :

I have LED lighting now in 2 rooms in the house. I use RGB LED strips, that operate from 12 V, connector on each end:

you can just click those in and put in series. Made a little controller for that:

Little GUI control panel (via ethernet)for it:

You can send music to the controller too, from the PC, DISCO lights!

As the light is over a big surface, it is betetr than 'bulbs' types.

Not as effcicient, there are resistors on the strips, but who cares.

I doubt you can make an inexpensive LED light which beats the efficiency of a CFL. A recent test in a consumer magazine showed that only the more expensive LED lights are marginally more efficient than CFL bulbs. Regular (tube) CFLs are even more efficient.

--
Failure does not prove something is impossible, failure simply 
indicates you are not using the right tools... 

"Nico Coesel"

** Efficiency is not the over riding issue.

There are so many deficiencies with CFLs, it is not funny.

1. They are ridiculously fragile.

1. They do not start or work well at low ambient temps.

2. They have a warm up periods of up to 100s of seconds.

1. They have very short lives if cycled often.

2. Most project light in useless directions.

1. They have nasty Mercury inside that is PITA if they break.

2. Most do not tolerate damp or wet conditions well.

1. Many places consider them to be hazardous waste.

None of the above applies to LED lamps.

In Australia, regular ( GLS) incandescent bulbs are BANNED from sale so we are forced to use CFLs and put up with all their faults.

For no sane reason.

.... Phil

Efficiency is not a sane reason? Carbon footprints? Hello?

Those depends on the quality. I always buy Philips long life.

There are probably some pretty toxic materials in LED lamps as well. Better sealed but you still don't want to burn them or have them in a landfill.

I moved to CFL lights over 10 years ago. My wife and kids have a habbit of leaving the lights on so with ordinary light bulbs it just got too warm in the house. Where possible I use tube CFL with an electronic ballast. If you want efficiency and long life thats the way to go.

--
Failure does not prove something is impossible, failure simply 
indicates you are not using the right tools... 

I started replacing incandescents in the late 1980s, when Home Depot started selling a dirt cheap under cabinet 15W linear fluorescent fixture. I use incandescents in 3 places: refrigerator, oven, and my Dim Bulb Tester.

Yawn. Plants thank you for that CO2

Unless plants are given more light and fertilizer they cannot use the extra CO2. There is no upside to filling the nest with feces.

"Philips Lumileds projects that LUXEON Rebel ES products will deliver, on average, 70% lumen maintenance (L70) at 50,000 hours of operation at a forward current of 1000 mA. This projection is based on constant current operation with junction temperature maintained at or below 135°C."

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Cheers, 
James Arthur