On Wed, 17 Jan 2018 09:19:31 +0000, PeterC wrote:

On Tue, 16 Jan 2018 09:31:25 -0800 (PST), harry wrote:

Came across this, interesting.
https://ledlam.co.uk/how-do-led-filament-work

'Filament' LEDs are, AIUI, COB and are probably the least inefficient
LEDs generally available. Morrisons have (had?) some 6W, 800lm, 'GLS'
B22 lamps, unfortunately ~3000K (I prefer 4000K+) for a fiver each. I
have one and it is good. I've not checked the actual wattage - OK, just
for you:
5W is flickering 4 - 5 and is just under %W based on VAxPF 15W, 1500lm
is similarly marginally low 60W incandesent shows 60W - surprising as
the voltage is ~245.

5 years ago I wouln't go below 80lm/W; 3 years ago I considered only
=100lm/W, with exception for GU10 for desk and bench lights that don't
spend long on.

Ikea changed to all Led, but those are worse than my benchmark 5 years
ago!

BTW, I bought from Ledlam some lamps that have COB on ceramic blades.
The blades are in a triangel and very translucent, with the 'back' of
each blade shining throght th gap between the other two, so near enough
360 deg.
The 3W is 320lm and the 5W is 600lm - this was 3 years ago! How progress
goes - not!

Five years ago (iirc) I thought the 78LPW Asda LED "60 watter" (810Lm at
12 watt rated - actual, 14 watt- consumption) was a worthy replacement
for a 20W CFL of nominally the same lumens output so I bought one to try
out. It proved to have a definite edge in lumen output compared to the CFL
it replaced - instant on for 6 watts less consumption!

That's since been replaced with a "10W" (actually 12 watts) 810Lm lamp
and my most recent LED GLS purchase a few weeks back from Home & Bargain
was a 3 quid 1500Lm 12W (actually a little over 13 watts) "100W
equivalent" E27 LED GLS lamp to replace an actual 100W incandescent light
bulb in the bathroom ceiling fitting (horizontally mounted lamp). Rather
pleasingly, it proved slightly brighter, most likely due to the 5 or 6
year old original bulb having become slightly blackened on its upper
surface as mounted in the luminaire.

I didn't bother comparing it against one of the three spare 100W E27
lamps that I'd purchased with the luminaire but I rather doubt I would've
been disappointed even if I had compared it to a brand new unused 100W
incandescent GLS lamp.

It's only now that we're starting to see 125 and 133 LPW LED GLS lamps
appearing on shop shelves despite one of Cree's CEOs promising that the
303LPW lamp they'd announced almost four years ago (Mar 2014) as a record
breaking laboratory 'Milestone' would be on the shop shelves in a time
frame of 18 to 24 months.

Up until about 6 months ago, I'd been stewing over this 'broken promise'
until I revisited the web page article and spotted, from Cree's very own
progress chart, that the historical reality approximated a lead time of
ten years[1] rather than the 2 years quoted by the CEO who one might have
expected to have checked out his own company's PR materials before
shooting his mouth off with unrealistic promises, D'Oh!

[1] According to the chart, it's looking more like a 12 year lead time
between laboratory 'Milestones' and shop shelves. The 131LPW 'milestone'
occurred way back in 2006, suggesting that we just might see 150LPW
product materialising in the next two or three years.

http://www.cree.com/news-media/news/...-to-break-300-
lumens-per-watt-barrier

--
Johnny B Good