Since they obviously have different phosphors it's also likely the spectrum is different too.
Most people would find 'daylight' bulbs too harsh for domestic lighting, except perhaps in the kitchen or a work area.
It is perfectly possible to make a 'warmer' looking tube with a good colour spectrum.
For "10 A" read "10 W" above. I bought one - it looks bright. No measurem ents.
And they do pay out.
Andy
Leds generally 'look' bright. But that's not how you measure light output.
Sainsbury's sell a true GLS 9.5W 806 lumen lamp for £5.99
Just wondering where the equivalant of a 60 watt GLS tungsten would be of much use?
Anglepoise
In a kitchen which is used for food preparation (as opposed to entertainment or just opening packets), high colour temperature lighting is useless for raw meat preparation.
On the whole, daylight lamps work well when used to provide daylight levels of lighting, but that would require lining the ceiling with loads of tubes. It looks unnatural to use such high colour temperature at indoor lighting levels which are nowhere near daytime sunshine levels. This relationship is described by the Kruithof curve, linking illuminance levels with what feels to be the correct colour temperature.
Yes, colour rendering index is unrelated to colour temperature, although your ability to distinguish close reds or close blues does depend on the intensity of that part of the spectrum, inversely modified by the overall intensity closing down your pupils.
Can be a problem with the lamp weight being much higher than the design rating, unless Anglepoise have changed the design to allow for heavier lamps since I last acquired an Anglepoise light 25 years ago.
With the wingnut type, I added rubber tab washers to the joints to increase friction.
The spring loaded type could be resprung if you can locate suitable new springs.
Don't be kidded. Just for once, the 806 lumen 60W tungsten GLS reference is actually based on the American 120v 750 hour standard which is about the equivilent of a 75W 240v 1000 hour lamp as sold in the UK and most of Europe (220v). IOW it's actually noticably better than a typical UK 60W GLS tungsten filament lamp.
The slightly less efficient 12W 806 lumen LES LED lamp I invested £3.49 on in our local Asda store about 3 months ago has a slight edge in light output compared to the 20W CFL it replaced. The CFL in question still being in its first flush of youth (i.e it was still at or above its "Design Lumens" output level).
The obvious difference being the instant full lumens output at switch on which reinforces the boost in brightness effect of which the missus is wont to complain as being "It's Just Too Bright!"(tm). It's fitted to an adjustable Ikea pendant fitting with metal "Chinese hat" lampshade hanging above the dining table in our kitchen / diner.
The kitchen half is lit by a four foot fluorescent lamp, originally a "40W" tube in a fitting fitted with a "Quickstart"(tm) transformer (which took 52 watts), recently replaced by a modern slimline electronically ballasted four foot 36W tubed fitting which, remarkably, consumes exactly that wattage.
As best as I could tell, the lumen outputs between the old and the new fittings were about the same. The 16W saving came at the cost of a less than perfect startup compared to the half century old "Quickstart"(tm) technology I'd crammed into the previous 'Slimline' fitting.
The new one does start 'instanly' but at a half output flickery level for the first half second from cold (as opposed to a fuss free quarter second ramp up to full brightness of the "Quickstart" circuit). It's only a 'small thing', the minor irritation of which I'll accept as the cost of the 16W savings.
However, at a guess, I'd say the 12W LES LED is producing at least half the lumen output of that 36w tube (which, until a year ago, would have been the most efficient light source - electronically ballasted linear fluorescent lamps four foot and over - avalable for domestic lighting). Since I paid a small fortune (circa 15 quid in B&Q for the fitting and tube) only about 6 months ago, it's not about to be upgraded any time soon.
I'll wait for the 200L/W LEDs to become readily available at non- stratospheric prices in a few years time before I put myself to the time and effort of such an upgrade exercise. For kitchen use, there's nothing better than a long linear light source, the longer the better, so I'll be looking at an extended LED based 'Strip Light' when the time comes.
In the meantime, I'll keep my eye open for more LED lamp "sub 5 quid Bargains" as and when they appear on the store shelves to replace my current fleet of CFLs.
An important aspect of the later more efficient LED based GLS lamps that should appear in the next 12 months or so is the reduced 'waste heat' output[1] from the 800 to 1000 lumen output lamps will make them more tolerent of poorly ventillated fittings, allowing their use where it previously wouldn't have been considered a good idea without replacing the existing lamp shade for a better ventillated one if you didn't want to risk premature lamp failure from overheated electronics (probably a major factor in the shortened lives experienced by some of the users reporting to this news group).
IOW, the 'modern' LED lamps of next year will not only make additional savings on electricity consumption, it'll make them a more universal replacement in fittings designed for tungsten filiament GLS lamps allowing you to retain the use of such fittings chosen purely for their 'stylishness'. No additional time and expense spent looking for suitable replacements in order to deploy LED lamps without compromising their life through overheating.
These are all good reasons to hang back and give Philips and Cree the time they reckon it'll take to bring their laboratory 200L/W and better samples they had produced early last year to market. They reckoned on an 18 to 24 month period bewteen lab samples and production lamps.
Assuming their estimates hold true, we should be seeing LED lamps with twice the efficiency of the current stock appearing on shop shelves by the end of this year, if not sooner.
[1] A point worth keeping in mind with such a doubling of efficiency is that an even smaller fraction of the total input energy will appear as 'low grade' waste heat depending largely on convective cooling for its dissipation.For example, assuming a 10W 810L lamp emits 2W as useful radiation in the optical frequency range, that leaves 8W to be shed as waste heat, mainly via convective cooling.
If we assume a doubling of efficiency, not only will an 810L lamp only consume 5W, converting 2W of that into useful radiation, the balance of 3W to be convected away will be less than half of the original 8W of waste heat. Even assuming that the greater efficiency is expressed as a doubling of the lumen output for the same 10W input, resulting in 4W of optical radiation in a 1620L lamp, we will see a reduction of waste heat down from 8W to a mere 6W which reduces the temperature of the electronic ballast components, given the same heatsinking efficacy.
There's more at stake than mere reductions of the electricity bill due to efficiency improvements; reliabilty is also improved by such efficiency gains. IOW, waiting for the improved lamps to appear is a win win game.
Right. I'm afraid I tend to like much higher lighting levels than you in a work area.
Not quite sure what you mean.
If you wish to display nice 'red' meat, you'd likely use an odd colour temperature. Preparation is a different matter, IMHO.
Yes, although it's not quite as simple as that, because the scatter from the rest of the sky gets bluer too, but it also gets darker faster. This can give redder illumination and blue shadows for items still in sunlight. You often get the redder sun also lighting the bottom of cloud cover as it drops near the horizon, further emphasising the red shift.
Dimming of filament lamps also shifts the colour to the red, keeping roughly to the Kruithof curve, whereas dimming of LEDs doesn't and is often regarded as displeasing as a result. However, there now are dimming LED systems which shift their colour to remain on the Kruithof curve.
Yes indeed, I was on Alderny at that moment, where we had totality.
Agree.
But I wonder if anyone has been measuring the current consumption of LEDs. It would be easy enough to produce a 'brighter' LED which actually uses a bit more than the competition. Not that anyone would do a thing like that, of course!
What kind of intensive behaviour modification do the S&M people use to produce turkeys which are self-basting?
====snip====
There's simply no point in trying to win the "Brightness War" by cheating on the power consumption figures. These days it's all too easy to check such consumption with a cheap 'n' cheerful plug in 'Energy Consumption Meter" (aka, digital wattmeter) which can now be had for as little as a tenner for ones that _now_do_ give meaningful readings below the 50W mark, unlike a decade ago when the £8.99 cheapies from ToolMart, Lidl and Aldi were simply a joke product[1] taking advantage of the fact that decently accurate digital wattmeters at that time were priced at 50 quid and more from specialist suppliers like Maplin and RS.
If you have such a wattmeter, you can measure the current drawn by the lamp if you like but you might just as well simply measure their wattage and be done with it.
[1] About a decade or so ago, whilst my dad was still compos mentis, I had him purchase an extra 'digital wattmeter' from ToolMart as an additional 'consumption meter to my trusty Metrawatt analogue wattmeter which I had purchased 2nd for a whopping 35 quid a decade earlier at a radioham rally[2].It proved to be totally unreliable measuring the power consumption of electronic kit and of questionable accuracy even for simple resistive loads less than 100W. If I hadn't already possessed that Metrawatt meter, I'd have merely only been able to infer its excerable accuracy.
As it was, I was in an excellent position to declare with no doubts whatsoever as to the crappiness of that and the DEM1379 Aldi version I later tried (which experiences rather sullied my regard of all such 'affordable' digital wattmeters for the next 8 or 9 years).
I've since acquired some trustworthy digital wattmeters from our local fleamarket's "Maplin Man" which I can recommend from personal experience. These are the N67FU and the L61AQ models (Maplin catalogue numbers - the latter is actually a UK version of the venerable Kill-A-Watt model sold in North America, now renamed "2000MU-UK" for the UK market).
[2] Although I rather balked at the high price of what was, after all, a 2nd hand meter, I must have instinctively realised that it was a (literally!) "Once in a Lifetime" opportunity to buy a virtually unique piece of measuring kit which has served me well ever since.I didn't appreciate just how rare such meters are/were until I tried googling for information on my Metrawatt example, of which there was none and a remarkable scarcity in regard to alternative contemporanous examples. rare indeed!
Now, thanks to modern digital electronics, it's possible for any Tom, Dick or Harriette to possess the means to measure true power consumption for less than the price of a couple of packets of cigarettes.
If you're really interested in the art of creating self basting turkeys, you need look no further than the Maddison Avenue crowd for the relevant experience.
I'm talking about preparation where you need to inspect the meat for imperfections, materials to trim off, etc.
Right. And daylight isn't any good for this? ;-)
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