Newbie saying hello... and starting to ask questions :-)

[chris_j_hunter]

yep, 'tis clear LEDs are opening lots of possibilities ... not sure they fit our budget just yet, to buy & to run, but 'looks like it won't be long !

>use 3x1w Cree or Edison p4 LEDs ...

but how does one tell what they are using in the lamps ... maybe I've missed it, but I don't think it's usually said where components come from ... ??

[Paul_B]

Chris,

In my experience a supplier will state the type of LED manufacturer for the high perfromance bulbs as well as Lumen (200 - 250 is about 30 - 40W Halogen) and beam angle (should be 120 degrees, quite often they are only 35 degrees which is rubbish). If these attributes aren't stated then I tend to steer clear.

My experience is that Nichia or Cree LED components are the best and around 3Watts with these will create a good result. The bulbs themselves don't look like the archetypal LED we are used to. These high performance LEDs are usually surface mounted:



The above bulb on Ultraleds is around £25 which I know is expensive and agree, but as said previously this is cutting edge technology and the price represents early adoption and research payback. However, it does show this technology is moving fast and getting cheaper.

Paul

[jpdw]

Slightly OT from the main topic but I bought one of these from Screwfix a couple of months ago. It seemed to have a noticable buzz which was rather too annoying. That said, if you dont mind the buzz it did seem to have a reasonable brightness curve. Not the finished article yet, but at least it's proof that at least some manufacturers are trying to answer the dimmable requirement as opposed to govt which seems to be killing the only working solution before there's a replacement.

My earlier post reminded me that I wanted to try this device again.

For the unitiated, it's apparently 20w, with light equivalent to a 110w bulb (we're going have to start know 'lumen' values aren't we!).

At full brightness, actually I quite like the light (in the living room ceiling). The room doesn't look like it's lit with a lamp -- if anything perhaps more like daylight.

The buzzing is still there.

In terms of dimming, for dimming-down, I'd say it dims down to about 10%. BUT the dim-up performance is not so good. Turning it on gradually you don't get anything till about 30% (ish). Then you can dim back down.

I guess the problem is that is still needs a certain level of start-up voltage to get the tube working. After that you can dim but before that you get nothing.

Anyway, my 2nd view is more positive, but still they have a way to go.

[toscal]

yep, 'tis clear LEDs are opening lots of possibilities ... not sure they fit our budget just yet, to buy & to run, but 'looks like it won't be long !

Ok I know I'm going a bit off topic. But LED lighting is cheap to run. Payback is usually around 3 to 5 years . We have just installed 12Watts worth of LED lighting in a classroom as part of a trial. This replaced 200W worth of Halogen lighting. And will save about 27 euros a year. Plus the bulbs won't need changing for over 20 years. Once the whole classroom goes over to LED lighting (we will be changing the Fluorescent tubes next week) they will see savings of about 100 euros a year for that one classroom.

[jpdw]

Anyway, my 2nd view is more positive, but still they have a way to go.

Well, it was more positive. Till the ******* thing went phut 5 minutes ago.
That's what? ... 2hrs usage...

The dimmer? A plain old analogue rotary job. Nothing fancy. And for most of the 2hrs it was turned up full.

By the smell I'd say something in the electronics has gone. The box says something like 1000 hours (from memory, it's outside in the conservatory with the smelly disgraced bulb). I guess I'd have fun trying to get refund/replacement out of screwfix.

[ludditeal]

Must admit that after posting the Screwfix link I read the reviews and they weren't good with quite a few failing very early on!

We need the drive to be quite bright when lit as the elderly in-laws live with us so I think that rules out LE'D's for the moment.

We did have some GU10 LEDs in the porch lights in the old house which used to be on all-night. After 3-4 months they were markedly dimmer from the continous overnight use. These were realatively cheap ones though. I swapped them for CFL's which were a lot better but they were taller in height, fortunately there was plenty of headroom in the void.

Regards
Allan

[Karam]

........ What I hope to achieve is...

There will be 5 driveway lights fitted with dimmable CFL bulbs. Initially I plan for these to come on at a fixed starting time but hopefully later move to a light sensor triggered start. I will want them to run at a dimmed level say 25%. There will then be 2 PIR's, 1 at the top and one at the bottom of the drive. When these are triggered the light level for the CFLs should go to 100% for a fixed time period, say 15 mins before dropping back to the base level. For the added compexity twist, at 01:00 in the morning the lights should go off all-together, but retain the ability to be triggered by the PIRs if movement is detected.
...............
Anyone see any problems with my plans? From my first play with Cortex I am not sure that I can do the light shut off at 01:00 which wouldn't be the end of the world.

As has been suggested there are often different ways of achieving the end result in Cortex. I can't keep track myself . But one possible concept to consider here is the ability to set the OFF dim level value via some other object such as the Scheduler (FYI: OFF and ON dim levels are usefully abstracted away from actual values in Cortex). The inbuilt light timer and light operating time functions can then be used to control the light ON timing as well as when entire function is operational (so use light timer only operational mode and PIRs can then trigger Start timer). The scheduler can then be used to change the OFF level to 25% at start of operational period and to 0% at 1am. Light level based automation for operational period can be substituted in later.

[chris_j_hunter]

wonder what would have happened if the Screwfix unit had failed while connected to a more sophisticated dimmer ... we had Superswitch security & touch-dimmer units in some rooms, years ago, and every time a bulb (tungsten) went we had also to replace a fuse (adding to the cost of the bulb) ... evenutually the units failed, too ... hopefully modern units / Idratek modules will do better than that, but it does seem an added risk to be using cheap bulbs !

[KirasHome]

Had a similar experience with some GU10 CFLs from Robert Dyas. Tempted by the cheap price (about £5) and bought 4 to replace the bulbs in the kitchen. I don't think any of them lasted more than 3 months (including two replacments after I complained to Robert Dyas). Not a happy bunny. Replaced them with some Megaman Dimmerable CFLs, twice the price, but so far (touch wood) not a single failure and the quality of the light's better. Happy bunny. The lesson? Buying cheap doesn't always save you money.

Jamie

[toscal]

A friend of mine says "cheapest is the dearest in the long run".