Well, CFL's also have heat issues, which is why they are not to be used in sealed lamp holders....
Ban Incandescent Lamps?
Everyone should check out this article....
Ban Incandescent Lamps?
Everyone should check out this article....
Indeed this is what I thought, but I also have some Linear Technology LED drivers that use an external MOSFET, but they are apparently limited. It seems that these actually use an internal BJT as the main switch and this is where the limitation comes in and the FET is there for other reasons, whereas the AL9910 doesn't use any internal switch. I can see that the AL9910 is a new product, but I'm having difficulty finding anywhere that sells the zetex/diodes products in the UK. So far all I've got is digikey and they aren't exactly practical. I don't suppose you know how to get these in small quantities? I could try ordering samples, but that doesn't quite seem right.
I think the reality is that the recalled lights were incompetently designed!
Thank you
and you're welcome, the hard part was finding where to buy the plastic domes from. These are actually sold as fillable baubles for example, the hard part was finding a supplier in the UK. I spray them with a glass frosting.Haven't read the entire link yet but...
The heat issue reminds me of the halogen craze from 20 or so years ago. Too many fires.
Comments on the mandate issue are forbidden. Let's just say I'm stocking up on ICLs.
I almost caused a fire when I was young, I knocked over a directional SES reflector style lamp and it came into direct contact with the sofa cover. Needless to say this was left for a while and when someone finally realised, there was a big hole burnt out of the fabric, good thing it didn't catch on fire.
We got our supplies through avnet knopp, its a big distributor... for places like digikey etc. Try and get samples, we got 10 of the normal ones (no use in combined light due to heat issues), and 20 of the ones with the metal underside as samples, and they wanted to know if we wanted more.... drop me a pm with your address and I'll see if I can mail you one to play with...
Agreed, though I believe that's always true in hindsight.
My purpose is just to answer the topic question and advise that before people fall over each other to get LED lighting there are issues they need to consider first. I have several LED lights myself and am very satisfied with them. For general lighting I'm going to wait awhile though.
I agree with you 100% on this, I really like the LED lights I have built too, but as a direct replacement for current household lights, I think they leave a bit too much to be desired. First of all they are too expensive and a poor design will not last the length of time they are advertised to. The product life span is one of the main reasons I'd want to switch to an LED, it makes it worth the extra cost, but if it doesn't last that long...
I think the LEDs need to easily out do CFLs with regards to efficiency and be somewhat cost competitive. I am sure this will happen in the next year or two, what with Cree and Osram having signed an agreement to work together on the issue, I am expecting great things out of the 'two heads' working together.
The area where I think you should definitely switch to an LED replacement bulb is with directional lighting, such as the typical 12v 20/50 watt halogen style. LEDs might not have much of an edge compared to a well designed CLF, but compared to a standard incandescent bulb... LED all the way. I got fed up of replacing the 20 watt halogen bulbs that I use and specifically went for an LED based part to get around that issue.
I purchased some dirt cheap LED mr16 replacement bulbs from china, the LEDS used were dismal, the light they emitted was green tinted and made you want to puke. I ripped out the insides and fitted some Osram golden dragon LEDs that I purchased cheap from ebay. Much better.
Prices are comming down steeply, we are aiming for a sub $20 10W LED retrofit production...
......... The one in the black packageing is the high dissipation one.
Have a look on the manufacturer's site for the datasheet, AN75 application note, and the excel sheet calculator (saves all the math stuff)...
The design of the LED is an art, especialy when it comes to chemical composition, it realy affects the output, colour, etc... same with difusers and lenses, You'll find a big diffirence between a good difuser and a plastic globe.
......... The one in the black packageing is the high dissipation one.
Have a look on the manufacturer's site for the datasheet, AN75 application note, and the excel sheet calculator (saves all the math stuff)...
The design of the LED is an art, especialy when it comes to chemical composition, it realy affects the output, colour, etc... same with difusers and lenses, You'll find a big diffirence between a good difuser and a plastic globe.
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There go the prices of mass production^^ Three XP-Gs for ~ 10 watts would set me back almost $20 on their own. Out of interest what LEDs are you using?
I have to say diodes inc. had completely escaped my radar, they have a nice selection of high performance and often lower cost parts that require minimal cost to implement too.
The AL9910 is probably a stand-out product as most IC manufactures don't produce a single chip HVAC LED driver.
I recently got a couple of modules from Bias Power. I haven't used them yet though. They have constant voltage and constant current types.
Did you mean the HV9971? Regardless of what part, so far I prefer the LT and diodes inc. HVAC chips mainly because the datasheets show you far more on the performance. On the face of things the AL9910 seems the better chip, higher efficiency and it doesn't require a transformer, although I wonder what happens to the power factor if you use it for say 80 watts, ie with two CXA2011 driven close to 1 amp, you'd probably need to use an active PFC circuit.
The application note comes with a basic PFC network, allthough it is optional, it seems to work fine without it. The main thing that stresses the driver chip, seems to be the frequency, the lower you can go the less work it does. But the inductor requirements get larger to the extent that it becomes hard to find off the shelf inductors that fits a retrofit and can handle the current of the LED plus ripple.
I would say as far as the LED interface goes the MOSFET would be your limit, as long as you can find one fast enough and with enough current switching ability, and voltage tolerance it should work. the chip can run up to 600V (under correction) rails.
I would say as far as the LED interface goes the MOSFET would be your limit, as long as you can find one fast enough and with enough current switching ability, and voltage tolerance it should work. the chip can run up to 600V (under correction) rails.
Power factor correction usually has nothing to do with the operation of the device in question. What happens is that the current drawn by the device leads or lags the voltage peaks, this doesn't affect performance, but like a reactive loudspeaker load it will pull the same current but from the opposing power rail. At it's worst this will result in the total power drawn doubling. Power factor correction increases the overall efficiency of the product at least this is as far as I understand it.
This is total rubbish.
You need to go learn some thermodynamics, to say nothing of arithmetic, and stop dismissing it as quibbling.
w
Sorry, but this is so far from being correct it's hardly worth disagreeing with in detail. It's true that the current leads or lags the voltage but this does not 'pull current from the opposing power rail' or result in an increase in the power drawn. Power factor correction is used because it reduces the required current carrying capacity of the wiring and switchgear.
Go look up real vs reactive or imaginary or apparent power.
AC power - Wikipedia, the free encyclopedia
w
There are 2 types of heat energy. Conducted heat (molecular agitation) and radiated heat. Molecular agitation gives rise to heat radiation (see black body radiation) otherwise known as infrared. As the temperature of the radiating body increases the wavelength of the radiation gets shorter, eventually becoming visible. This is how an incandescent bulb works.
Waves of any frequency (wavelength) heat surfaces that absorb them, hence the 83% infrared that you quote reverts to molecular agitation without ever being visible. The total heat produced by an incandescent lamp i.e. energy which never becomes visible light is therefore 95%
You can call this 'thermodynamic quibbling' if you like, but the rest of us simply recognise it as an accurate description of what is going on.
w
I must admit I hadn't looked into PFC at all really, simply putting what I know about reactive loudspeakers into the context of the mains line.
What I meant by opposing rail was a very poor choice of words as that doesn't exist in the mains line and the more I think about it, what I wrote doesn't make a lot of sense, except for the part where the total power consumed by the device is reduced. I guess you could say that it isn't the device that is strictly consuming the power either, as it's dissipated in the wiring, but without the device the wires wouldn't be dissipating anything either. I'll go look at the wiki article
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