LED lamp outputs

[zcacogp]

Chaps,

A quickie.

What's the difference between these two lamps. Both are GU10 LED system, from different suppliers. Both are 1.8 watt (this is presumably the power consumption).

This one is from Toolstation, has 20 'clusters' (presumably that means 20 LEDs, working out at 12v each), and claims an equivalent power output of 20 watts.

http://www.toolstation.com/shop/Lighting/Spot+Lamp...


This one is from TLC, has 21 LEDs (therefore 11.4v each) but claims an equivalent light output of only 10 watts. (It's also about half the price, but is on Special Offer.)

http://www.tlc-direct.co.uk/Products/GULEDW.html


Why the difference in 'equivalence'? Are they going to be substantially different LED's themselves in the lamps, or are two different people using different conversion factors for LED power to output light power?

(FWIW, I am planning to buy a couple of these lamps, dismantle them and arrange the LED's themselves in a string as under-shelf lighting for some shelves in our lounge. Seems like a MUCH cheaper option than the likes of this:

http://www.tlc-direct.co.uk/Products/FL4205WH.html

... which would work out about nine times as expensive for what I want to do with it. At the moment I have time and not money, so the hassle factor isn't a problem.)


Oli.

[Goochie]

It is possible that there is actually no difference between the light output of either. Pretty much all GU10 LED cluster lamps of this type will have the same light output when measured side-by-side. The problem is that without proper photometric data for each, it is impossible to see which one (if any) is better than the other.

The websites you've linked to are just wholesalers who put up whatever information the lamp manufacturers give them, naturally the manufacturers will be selective in the information they use in order to make their lamps seem the best.

How are you planning on driving the LED's once you've removed them from the enclosure? Do they require a constant current or constant voltage driver?

IMHO you're going to be wasting a lot of time trying to achieve something that could easily be done by alternative means, such as a dedicated LED undercupboard light.

If you really want to DIY it, then why not try something like these:

http://uk.rs-online.com/web/search/searchBrowseAct...

Edited by Goochie on Sunday 1st November 23:02

[zcacogp]

Goochie,

Thanks. Pretty much as I expected. I've never seen photometric data listed for an LED light, so I guess all I have to go in is that 'selective' information.

In terms of driving the LED's, I'd simply use whatever circuitry is present in the lamp. I'd dismantle the outer casing, remove the LEDs and line them in whatever formation I want (long line), and put the small PCB which is probably present in the base of the lamp into a box, and wire it all together. I'd do this three times, once for each shelf, and have them all on a common switch.

Yes, I could go for the individual LED option, but those which you linked to are 53p each, or £13.25p for 25 of them (and that's probably without VAT). And that's without the driver circuit. If you buy them in a lamp, as I am proposing, you'd get 21 for just over £4, including the driver circuit. Doing three shelves (therefore three lights), that'll save well over £30.


Oli.

ETA: Just seen you suggested a dedicated LED cupboard underlight - as I linked to in my first post, coming in at well over £100 for the whole project.

Edited by zcacogp on Monday 2nd November 08:31

[jshell]

I got these, they're ace! Fully adjustable (parallel or series) underlighting set for under £50.


http://www.ikea.com/gb/en/catalog/products/3011940...