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74 posts

Master Geek
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  Reply # 589989 3-Mar-2012 19:40 Send private message

I recommend using the Phillips bulbs. There are several options that you need to think about. The wattage, the colour and the angle. 
Best to go online and look at what Phillips list. Colour is important and I have found the white 4000K bulbs good as lights in the kitchen but prefer the warm white 2700K in living areas. I have used them to replace 12v halogen bulbs and it is hard to see the difference between them and the 2700K 10watt 60* Phillips LEDs  

 

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  Reply # 590000 3-Mar-2012 20:08 Send private message

In the old days (1990...) it was really hard to produce a blue LED. But when they got it working it was a pure blue. They (Philips?) have now used their knowledge of CRTs and make a phosphor film they place in front of a high intensity blue LED light source, then the phosphor glows a wide spectrum white light which look as natural as an incandescent. I saw a demo last year of the first one in the country. Still only for corporate use, but it is the next generation of LED lighting that will filter down to consumers.

The issue with a white LED is that it is not that easy to produce white and keep it cool so in a traditional bulb fitting and white LEDs you are limited to about 10W (~75W incandescent), but with blue and phosphor your efficiency goes up.




You can never have enough Volvos!




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  Reply # 590020 3-Mar-2012 21:23 Send private message

What would you recommend in a home office in terms of "colour"?

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  Reply # 590022 3-Mar-2012 21:49 Send private message

I have 6500K everywhere because I cant stand yellow, but many of the cheaper "6500K" ones are more like 8000K so look like halide headlights for colour - not very nice.

anything lower than 3000K is disgustingly yellow, and the ones around 4-5000K still look pretty non white to me.




Richard rich.ms

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  Reply # 590027 3-Mar-2012 22:04 Send private message

Niel: The issue with a white LED is that it is not that easy to produce white and keep it cool so in a traditional bulb fitting and white LEDs you are limited to about 10W (~75W incandescent), but with blue and phosphor your efficiency goes up.

Well I learnt something, I always thought white LEDs were UV plus phosphor, but according to Wikipedia most are blue plus phosphor.
But what do you mean by "traditional bulb fitting and white LEDs" as apposed to blue and phosphor?

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  Reply # 590192 4-Mar-2012 15:12 Send private message

Skolink:
Niel: The issue with a white LED is that it is not that easy to produce white and keep it cool so in a traditional bulb fitting and white LEDs you are limited to about 10W (~75W incandescent), but with blue and phosphor your efficiency goes up.

Well I learnt something, I always thought white LEDs were UV plus phosphor, but according to Wikipedia most are blue plus phosphor.
But what do you mean by "traditional bulb fitting and white LEDs" as apposed to blue and phosphor?


Sorry, should have clarified.  I was referring to normal recessed fittings and pendant fittings where heat is trapped (air flow limited).  So it is hard to keep a high power LED lamp cool unless the fitting is designed for it.  I've seen some bulbs with a built-in fan, but they soon clog up with dust.

The LED lamp I saw has an array of blue LEDs and a couple cm away was a sheet of phosphorous material.  LEDs are narrow angel but with this setup you get a good spread of light which you don't with traditional white LEDs.

I've got a 50W warm white LED at home.  Nice and bright, but it is only the LED and needs a heat sink + fan.  It is actually an array of LEDs potted onto an aluminium/copper plate.  Cost was about $40 from China.  My idea was to under drive it with say 20W so the large plate will help getting the heat out.  But then I've found recessed fittings with I think 9 x 2W LEDs which will be a direct replacement for our incandescent recessed fittings.  Cost is around $50 x 45 fittings...  And I'll have to replace the power supply as it is not approved for NZ, so still considering alternatives.




You can never have enough Volvos!


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  Reply # 590193 4-Mar-2012 15:14 Send private message

Multiple led downlights make horrid shadows with many hard edges overlapping. Approval only needed for resale if they are not permanantly installed.




Richard rich.ms

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  Reply # 590365 5-Mar-2012 06:20 Send private message

richms: Multiple led downlights make horrid shadows with many hard edges overlapping. Approval only needed for resale if they are not permanantly installed.


The 50W plate I have is I think 18 LEDs but it is in an area of only about 1" x 1".  And optics does wonders for harsh shadows.  3m stud height also helps ;-).

All mains electrical products need to have c-tick and a few other things, unless it is 10 or less engineering samples or you manufacture it in extremely low volume.  Electronic transformers included.  If you import goods yourself, fixed or plugged in wiring, and a fire results then you will have difficulty with your insurance.  Last Winter there was an instance of a fire from an imported decorated panel heater sold I think on TradeMe.  The insurance paid out for promotional purposes, and stated they do not have to since the product did not have the correct NZ approvals.




You can never have enough Volvos!


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  Reply # 590913 5-Mar-2012 21:53 Send private message

Niel: I've got a 50W warm white LED at home.  Nice and bright, but it is only the LED and needs a heat sink + fan.  It is actually an array of LEDs potted onto an aluminium/copper plate.  Cost was about $40 from China.


Could you please provide a link? A friend and I were actually talking about making something like that.

Watchmaker Wizard
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  Reply # 591357 6-Mar-2012 17:22 Send private message

How big an issue is the heat from these things? Enough that a large room of LED lights will be humming due to noise of the cooling fans, or is it mainly to improve their longevity?





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  Reply # 591364 6-Mar-2012 17:39 Send private message

Was going to give details, just did not have time when I posted.

Deal Extreme http://www.dealextreme.com/
Shipping is free, but can easily take 6 to 8 weeks. Do not believe the quoted intensity, consider it to be 50 to 75 lm/w and you should be safe. As a reference, Cree has some high power LEDs that now reach just under 100 lm/W... Also consider many of the (consumer) products to be rejected batches from as minor as a typo to as major as a media player with no heat sink on a CPU so it overheats within 5 minutes. Also when you find something you like do a search on eBay to see if you can get it cheaper.

Deal Extreme also has a 100W plate, but is outside my current budget.

If you want an air swimmer for US$16 (or other consumer goods), go here: http://www.gadgetsdealer.com/

There is also a web site Made In China.

Many of the products on TradeMe actually come from the above (and similar) web sites. Avoid the "corn cob" style LED lamps, unless you have an enclosed light fitting which will protect it from getting knocks - they fall apart.




You can never have enough Volvos!


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  Reply # 591500 7-Mar-2012 08:46 Send private message

I am running a trial with a GU10 5W high power bulb at the moment. It is on a four bulb strip light in our kitchen.

http://ledstuff.co.nz/product_info.php?products_id=283

So far I am impressed. Colour is very similar to the existing halogens and brightness is same or slightly more. I did initially get one from mega Mitre 10 but it literally lasted a couple of hours and then went pop (loudly) it was also much much dimmer.
Once the next halogen pops I will replace the remaining bulbs with the same LED.







Media centre PC - Case Silverstone LC16M with 2 X 80mm AcoustiFan DustPROOF, MOBO Gigabyte MA785GT-UD3H, CPU AMD X2 240 under volted, RAM 4 Gig DDR3 1033, HDD 120Gig System/512Gig data, Tuners 2 X Hauppauge HVR-3000, 1 X HVR-2200, Video Palit GT 220, Sound Realtek 886A HD (onboard), Optical LiteOn DH-401S Blue-ray using TotalMedia Theatre Power Corsair VX Series, 450W ATX PSU OS Windows 7 x64

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  Reply # 591688 7-Mar-2012 13:00 Send private message

Just dont get the corn lamps. series string of cheap leds so when one dies half the lamp dies. And they are.just running on a capacitor dropper so will smoke up on inverter/ups square wave power. And the flicker. ick.




Richard rich.ms

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  Reply # 591839 7-Mar-2012 16:23 Send private message

Niel: Was going to give details, just did not have time when I posted.

Deal Extreme http://www.dealextreme.com/


Can you please post part numbers. I have spent hours on Deal Extreme in the past looking at LED lamps, and don't want to spend time searching for what you have.

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  Reply # 591844 7-Mar-2012 16:33 Send private message

Nety: I am running a trial with a GU10 5W high power bulb at the moment. It is on a four bulb strip light in our kitchen.

http://ledstuff.co.nz/product_info.php?products_id=283

So far I am impressed. Colour is very similar to the existing halogens and brightness is same or slightly more.


Are you using 35W halogens for the other bulbs? At only 400 lumen I would expect these to be significantly less bright than a 50W halogen (650 lumen). Very impressive efficiency though, at 80 lm/W overall!

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