LED replacement for 48" fluorescents

Commercial LED lighting is getting better and better. In my quest to add a wine glass rack in the butler's pantry of our new house, I had to replace the under-counter CFL lighting with two LED strips (each of

("Dry" installed to check fit before finishing.)

And my other lighting projects...

...Jim Thompson

I see you gave up on the chinese globes?

Cheers

Bad photo with sunlight behind them, but they're level enough to keep even me happy ;-) ...Jim Thompson

What are those hideous gangly things in the left corner?

firewood in case it gets cold? :P

alternatively a dust collector

-Lasse

Giant Calamari?

Guiducks on Viagra?

Baguettes from Boulangerie Festus?

Cheers

Phil Hobbs

Agave (aka Century Plants) spears. They flower once, sending spears skyward, then die. ...Jim Thompson

-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

So how's the water there?

Cheers

Phil Hobbs

Defaming >:-} Little old biddies always need something to do. ...Jim Thompson

This is 20 units of the Cree XPEBWT-01-0000-00CC2 LED, for a total of 4580 Lm. And, since these ligts are on a LOT all day and especially in the evening, I wanted to be sure that the whole system was efficient.

The power supply is the Thomas Research Products LED25W-72-C0350 which is supposed to be 86% efficient.

Well, I am certainly confident it is more efficient than fluorescents with magnetic ballasts.

Jon

Do you know that there are commercial 48" (T8) LED tubes available? While building your own is commendable, it's not really economical:

Yes, I'm aware of them. The tube gadgets may have cooling problems, they probably need the tube because they are not isolated from the line. Also, they are 100 Lm/W, the LEDs I'm using are 229 Lm/W (although that doesn't include the power supply losses, so it comes out just under

And, those retrofit tubes are apparently mechanically interchangeable with standard fluorescent tubes, I can easily see somebody making a mistake and blowing something up. The cheaper ones give 900 Lm for a $30 unit, I'm getting 4580 Lm from mine, for about $62. And, I am using about the same electricity as two of the tube retrofits, but getting 2.5 X the light. So, I think this is actually about as economical. Depending on longevity, I may come out well ahead.

Jon

I'll bet mine uses fewer transistors. :)

The 3W LEDs were on sale at 100 for $30 (free shipping), so even though they're probably the lower efficiency kind (definitely not Cree), having more gives plenty of light.

Tim

-- Seven Transistor Labs Electrical Engineering Consultation Website:

If those "1 W" LEDs are specified for 350 mA maximum current and you are running them at 300 mA, the phosphor will quite quickly (in a few thousand hours) loose the efficiency and the light will be discolored.

Some lamp producers claim tens of thousand hour life time, but then you have to run the LEDs at 1/2 or 1/3 of the maximum rated current.

The maximum efficiency [lm/W] also occurs around such currents, thus, you get more light running two LEDs at 150 mA than a single one at 300 mA.

Of course, the thermal design is also greatly simplified at currents below half of the maximum rated current.

Contrary what you said in your original post, these are actual "3 W" LEDs with a maximum current of 1 A. Since you are running them at only

Where did you get those 200+ lm/W figures ?

I only found such figures for CREE single color LEDs, not for cool white series, not to mention any warm white series. For cool white, the values were around 120 lm/W at 350 mA and Tj=120 C, for Tj=25 C values like 140 lm/W could be found. So at initial turn on, you get

I thought it being true was an absolute defence to the spurious charge of defamation or is the USA different? Presumably the court will hit the water company with punitive damages if they persist. I don't much fancy the poor woman's chances of getting a reliable water supply in the future though - she had better start digging her own well!

Water running coloured usually just means that something has stirred up the silt in the supply pipes. Local digging or a very heavy vehicle.

One of the show pieces we used to do for visiting VIPs was to analyse the tap water on our ultratrace ICPMS kit. There was always traces of most elements lead, uranium in it at well above baseline as they are common minerals and widely distributed in the earth. Mineable uranium ore is very rare but roughly 2ppm of most rocks and soils is uranium.

We were banned from doing it because it upset water companies who after the semiconductor chemical industry and universities rapidly became big and important customers for the kit. No sample prep required.