02-04-2007, 02:18 PM
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#139 (permalink)
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| | Re: Do not feed the Dinosaur!
Eeyore wrote:
>
> Bill Baka wrote:
>
>> Eeyore wrote:
>>> Bill Baka wrote:
>>>> Eeyore wrote:
>>>>> Bill Baka wrote:
>>>>>> LEDs are better than incandescent lights,
>>>>> What do you mean by better ?
>>>> Much more mechanically robust, smaller, new and evolving technology, and
>>>> little thermal wasted on a hot filament.
>>> Why does 'new technology' = better ? Keeping powerful LEDS cool is actually a > serious concern ! The big ones need heatsinks.
>> I am thinking of my CatEye and it puts out a decent beam at very low
>> power. Not a search light but enough.
>
> Enough to illuminate your house with ? No !
>
> And you failed to address this one. Why does 'new technology' = better ?
It can be better if used for things other than I-Pods, cell phones, and
play stations. If a better LED comes out then new technology is good,
but there is a lot of research going into super efficient LEDs.
>
>
>>>>>> maybe on par with fluorescents, Their efficiency in lumens / watt is currently >>>>typically no better than 50% of that of CFLs
>>>> Even fluorescents make the light as a secondary effect.
>>> So what ?
>> I'm trying to educate you, if possible.
>
> You pompus ****. I know exactly how they work.
>
> As I said before.... So ? The method by which light is produced is irrelevant.
Pompous? Maybe. The problem I have with HID lights is that they take a
lot more electronics to strike the arc and to maintain it. It takes
maybe a thousand volts to start then maybe 50 volts once it is going.
Complexity makes for lower MTBF.
>
>
>>>>>> and don't need a minimum voltage to run the electronic ballasts.
>>>>> In exactly what way don't they ?
>>>> The ballasts have a minimum workable voltage. Transistors optimized for
>>>> 110 VAC rectified don't like low voltages.
>>> Nonsense.
>> Try running at half voltage and see what happens.
>
> Your statement " Transistors optimized for 110 VAC rectified don't like low voltages." is utter bollocks. Only a half wit would try running a lamp rated
> for mains voltage on half that. If you *wanted* one that'll run on a wide variety of voltage it's easy enough to do.
>
You bit. The Europeans are ahead of the Americans on power supply
requirements. Auto sense and power factor control make it easier to just
plug into any voltage available.
> Try running your LED on 'half voltage' btw and see what hapepns.
Half voltage on the LEDs themselves gets you dark. My Cat eye white LEDs
run at 3.3 volts through about 20 ohms of resistor to the batteries.
Simple and not that efficient with the resistor waste but I get enough
light from 4.8 volts of NiMh and quite a bit more if I use alkalines and
use 6 volts. Any more waste than that and I might design a circuit to
control the light intensity. If I got lucky maybe I could sell the idea
to Cat eye.
>
>
>>>> Just look at the back of your computer and see if there is a 110/220 switch.
>>> If there was a demand computers could run on 12V too. Laptops actually run off 19V > typically and you can also get 12V DC CFLs.
>>> http://cgi.ebay.com/Compact-Fluoresc...QQcmdZViewItem
>>>
>>> The line voltage is not even remotely the issue.
>> It was just one example.
>
> It was an example of you talking out of your backside.
Forget line voltage then and I will stick to DC.
>
>
>>>>>> I think 100 watts would be the output for an average person
>>>>>> and even that might be pushing it for a person in a developing country
>>>>>> who may not have enough good nutrition. At 100 watts, solar panels start
>>>>>> to be a major investment and don't work too good at night or on hazy
>>>>>> overcast days.
>>>>> I don't rate solar panels as an intelligent solution to today's energy issues either for >>> ppl who live on-grid.
>>>> Why not? Even at only 20% efficiency they are better than fossil fuel.
>>> No they're not. Not remotely in any way practical for most of the world.
>> Some of the newer types are getting cheaper to produce, but they need
>> sales volume to knock down the cost.
>
> Not true. Solar panels are being produced in such numbers that they're way past being costly just because they're 'new'. The simple truth is that they're
> expensive because they use lots of expensive semiconductor grade silicon.
This is where technology comes in. I know for a fact that there are some
innovative things going on. One process involves a roller that makes
flexible sandwiches out of different materials but is still in development.
>
>
>>>> That is the sticking point for right now. All kinds of money is being
>>>> spent on research to find a solar cell that goes to even 30%.
>>> Even that doesn't solve the problem that no sun = no power output !
>> I think I mentioned that. Most places have sun most of the time.
>
> Most places in the USA have a daily average of no more than 4-5 hours worth of decent insolation that provides the panel's rated output.
>
Better 4-5 hours than none at all.
> Have you not heard of dawn, dusk and nighttime btw ?
Yes, and the moon makes for some interesting riding with the light off.
>
>
>> The effort should be made, starting with sunny areas.
>
> Made by whom ?
The government if nobody else, and that is what I don't want. Joe
consumer is just clueless about ROI spread over the next ten years or so.
>
>
>>>> If we would just start buying what is available now instead of waiting for the
>>>> Nirvana of more efficient solar cells we might be digging out of our oil
>>>> problem.
>>> You'be making it worse more likely.
>> Please explain your logic.
>
> Making those solar cells is energy intensive.
Better them than more time wasting games.
>
>
>>>> Not enough windy spots for windmills, unless of course they could be
>>>> utilized in a hurricane and suck up the power of nature on a rampage.
>>>> I know I'm dreaming on this one.
>>> Plenty of places that can (and do) produce wind power in Europe. Offshore generation > is becoming very popular.
>>>
>>> You've completely failed to address the isue that most leds just produce a single colour > btw. Great for traffic lights. Not so good for lighting your
>> house.
>>> Graham
>>>
>> There is a grain of truth in that, since the cheapest LEDs put out only
>> one wavelength.
All single mode LEDs put out a single and very precise wavelength. If
you look at the specs you will see things like 532 microns, etc.
The color is absolutely tied to the materials making the light, no
variances.
>
> Wrong again. They put out a spectrum of wavelengths but centred round one colour. It's nothing to do with whether they're cheap or not either. The same
> happens with expensive LEDs.
See above.
>
>
>> Green or yellow would be adequate for most purposes
>> since that is where the human eye is most sensitive.
>
> Idiot. You want your house illuminated with yellow light ?
Cool man, pass me another joint.
The idea was that you can see enough to navigate with only one color,
not have brilliant Dolby surround technicolor light. If yellow light
makes me see an obstacle then I will use yellow.
>
>
>> Pure white LEDs have 3 colors that mix into white as seen bye the eyes.
>
> Absolute rubbish.
>
> They have blue LEDs that shine on a phosphor that then produces what looks like white light. YES ! A phosphor - just like in fluorescent tubes !
>
> Nor is the white 'pure'.
>
> " Most "white" LEDs in production today are based on an InGaN-GaN structure, and emit blue light of wavelengths between 450 nm – 470 nm blue GaN. These
> GaN-based, InGaN-active-layer LEDs are covered by a yellowish phosphor coating usually made of cerium-doped yttrium aluminum garnet (Ce3+:YAG) crystals
> which have been powdered and bound in a type of viscous adhesive. The LED chip emits blue light, part of which is efficiently converted to a broad spectrum
> centered at about 580 nm (yellow) by the Ce3+:YAG. The single crystal form of Ce3+:YAG is actually considered a scintillator rather than a phosphor. Since
> yellow light stimulates the red and green receptors of the eye, the resulting mix of blue and yellow light gives the appearance of white, the resulting
> shade often called "lunar white". This approach was developed by Nichia and was used by them from 1996 for manufacturing of white LEDs. "
> http://en.wikipedia.org/wiki/Led
>
>
>> I haven't looked nto the technology all that thoroughly
>
> You're telling me !
You win. I get tired of reading electronics magazines for the last
little detail. The holy grail would be to get an LED to emit the light
without a booster phosphor.
>
>
>> but I do know that white is perceived when you shoot out a mix or red green and blue.
>
> That's about the first thing you've got correct.
It's how color televisions work, faking the eye into think that a color
is present.
>
>
>> Another fact
>> is that around here the traffic lights have all gone to LEDs. They don't
>> burn out like the old incandescent lights so they don't need the bulb
>> changed every six months.
>
> That's because the cost and inconvenience of replacing them is high. Irrelevant to home use.
That actually was the reason, labor.
>
> Don't prattle about stuff you don't understand ever again.
I understand it but I admit to being a bit off the mark on what is being
produced today. The troll technique never fails.
Cheers,
Bill Baka
>
> Graham
>
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