New bulbs. - Page 8

entwisi · 13-03-2007, 20:57

I think you need more than contaminated water to put up with the stink from "The Tip"

Neil · 13-03-2007, 21:02

It makes me laugh how the people in the new houses up there complain about the smell. Er hello you bought a house next to a tip what do you expect?

Ianto.W. · 13-03-2007, 21:31

What bugs me about this thread is the amount of times references are being made to qualify certain members arguments, is reference 'wikepedia' and the like, I myself have never visited these sites and rely only on past experience to back up my theory, so do not seek to pontificate from an encyclopedia on us old uns that have been there and done it.

entwisi · 13-03-2007, 21:42

Past experience gained from where Ianto? At some point someone had to find that info out. be it a text book, or any other method, there is always a point of reference. an encyclopedia is just such a tool. wikipedia is just an open source version of such. They are just as valid (if not more so as there is no chinese proverb effect) as your past experience

Ianto.W. · 13-03-2007, 22:09

Quote:

Originally Posted by entwisi

Past experience gained from where Ianto? At some point someone had to find that info out. be it a text book, or any other method, there is always a point of reference. an encyclopedia is just such a tool. wikipedia is just an open source version of such. They are just as valid (if not more so as there is no chinese proverb effect) as your past experience

The piont is Ian these were not available to us old sparks, only to you bright sparks. A 6year apprenticeship many mistakes and 'belts' taught jambutty and myself the game, not a world wide web. You should bless the day that you and your fellow experts were born into the generation you are in.

andrewb · 13-03-2007, 22:17

Quote:

Originally Posted by Ianto.W.

What bugs me about this thread is the amount of times references are being made to qualify certain members arguments, is reference 'wikepedia' and the like, I myself have never visited these sites and rely only on past experience to back up my theory, so do not seek to pontificate from an encyclopedia on us old uns that have been there and done it.

I must confess I had to research the solar cell's working better with red light rather than blue on the internet but the rest of what i've wrote in this thread is knowledge I already had.

I spent quite a long time making sure I understood things correctly, and in terms of researching the solar panels I made sure that a number of sources mentioned it. I think the physics behind it is quite high level so its not the easiest thing to find, and I won't even attempt to try and learn it because, well, sometimes you need to accept things without fully understanding them. Something Jambutty isnt used to!

entwisi · 14-03-2007, 08:35

Quote:

Originally Posted by Ianto.W.

The piont is Ian these were not available to us old sparks, only to you bright sparks. A 6year apprenticeship many mistakes and 'belts' taught jambutty and myself the game, not a world wide web. You should bless the day that you and your fellow experts were born into the generation you are in.

So when on an apprenticeship you didn't have some old lag to teach you? No one told you anything about it? There have been these things called books for quite some time now. I know you and Jambutty seem ancient

but I'm sure books predate both of you. The only difference then to now is that I don't have to trail to the library, look through wjhat they had, search teh index, order a particular book and wait for it to be delivered. Now I click a few buttons and the info is there. The info itself has probably chanegd very little, just the ease of access to it.

I work in an environment where I'm at the bleeding edge of web technologies. I have to research whats happening and how it works just like you did when serving your time. only thing with me is that the stuff I research is in constant flux so you can't assume stuff you learnt about it 3 weeks ago is still valid or the best practice now of how its being used.

DeShark · 14-03-2007, 08:56

Quote:

Originally Posted by jambutty

Very true but how much heat does a torch with a blue filter over the lens produce that can have an affect on my calculator? Undoubtedly some infrared will filter through as well as will other spectral colours because the blue filter is unlikely to be a perfect blue.

The bottom line is that my calculator will be activated by light from any source and it is the brightness (or amount measured in lumins) of light falling on the solar panel that will determine at what point the calculator will become operative. Where the light comes from or what colour it is, is irrelevant. The blue end of the spectrum has more energy than the red end and therefore I conclude that more energy means a brighter light. With a 10% differential between the outer limits of the spectrum as shown by http://www.iee.cz/iwtpv04/6-Pociask.ppt slide number 32 it is hardly a major factor.

In any case the point being made applies to, presumably, a modern solar cell. My calculator is more than 20 years old.

The only way we could completely say that it's not just the IR that is responsible for power production in your calculator we'd need to block the infrared light from hitting the solar panel without blocking the visible As you can see at - http://members.misty.com/don/irfilter.html - it's not the cheapest nor easiest thing to do.

I hesitate to suggest it, but a sheet of glass may be a reasonable makeshift blocker of infrared light. Placing say your magnifying glass over the solar panel might wield some interesting results but it's nowhere near a perfect filter. What we could do instead is find a source which produces the same luminosity but doesn't emit as much infrared and see what effect that has. Which would be... a LE bulb. Luminosity and radiance are two different things. The incandescant bulb is more radiant but the two are both equally (as near as will make a difference to your calculator) luminous. I have to go though now cause I have a lecture soon.

Your argument about blue light = more energy = more power produced by the calculator is not correct as I pointed out. The blue photons are not able to produce an electron hole as they have *too much* energy and hence cannot be absorbed. You can research all this yourself I'm sure and show me a webpage or quote a textbook. Big library here I'm sure I'll find a copy. Nice debate, it's causing me to remember my quantum phys from a-level. As well as teaching me various things about solar panels and LE bulbs.

DeShark · 14-03-2007, 13:00

Quote:

Originally Posted by DeShark

Your argument about blue light = more energy = more power produced by the calculator is not correct as I pointed out. The blue photons are not able to produce an electron hole as they have *too much* energy and hence cannot be absorbed. You can research all this yourself I'm sure and show me a webpage or quote a textbook. Big library here I'm sure I'll find a copy. Nice debate, it's causing me to remember my quantum phys from a-level. As well as teaching me various things about solar panels and LE bulbs.

I was in quite a rush when I first wrote that and wasn't quite thinking straight. In fact, I was almost talking gibberish. It's hard to explain all this without explaining the structure of the atom, absorption of a photon by an atom, electron excitation, covalent bonding and the effect of an incident (incoming) photon on such a covalent material. Thus I'll have to simplify the model somewhat.

In a typical solar panel (The things haven't changed much since their invention except in the purity of the silicon produced), there is a layer of a semi-conduction material (silicon with impurities embedded). The atoms in this layer share electrons with each other and the lorentz forces (electro-magnetic) between nuclei and electrons will keep the atoms and electrons held together. The electrons can be either "localised" (restricted to move around one or two atoms) or "delocalised" (free to move around the whole structure). (Roughly speaking) When the electrons are delocalised, the material is conductive but when the electrons are localised, the material is an electric insulator. When a metal (conductor) is subjected to incoming photons of high enough energy the electrons are given the energy of the photon which increases their speed enough for them to leave the metal completely (aka The photo-electric effect). In a semi-conductor (such as silicon) the electrons are on the border of conducting and non-conducting.

You could say your solar panel is like Goldilocks. If a photon comes in with too little energy, the electrons are unable to move into a free state. They remain "bound" to the atom and do not conduct. If a photon comes in with too much energy, the energy cannot be given to the electron. The energy is converted to heat. The silicon layer heats up and does not conduct. If however, the energy is "just right", the silicon layer becomes conductive, the electrons can flow freely and an electric current is induced. This amount of energy which is "just right" is known as the "band-gap energy". As I said before, for silicon it's about 1.1 eV (electron-volts). This is infrared light.

I really can't spell it out any more. The bottom line is that your calculator will NOT be activated by light from any source and it is NOT the brightness (or amount measured in lumins) of light falling on the solar panel that will determine at what point the calculator will become operative. It depends on the frequency of the light and how intense *that specific* frequency is.

Ianto.W. · 14-03-2007, 13:09

Quote:

entwisi. I know you and Jambutty seem ancient but I'm sure books predate both of you

I was quite amused by this statement Ian, I was also predated by the booze that prompted me to 'liven' this thread up. As a 15 year old we did not rewire houses we converted them from gaslight, everything was done with hand tools, not the electric type which we did not have anyway, flourescent lighting was very crude and heavy in those days, so yes books are about the only thing that predated us, just imagine fitting a switch to a stone wall without an electric drill.

entwisi · 14-03-2007, 13:46

Glad it amused you

BTW, I've had to use hand drills before now thanks.... My dad used to make me use a hand drill when he was teaching me to drill out broken cylinder head bolts so I would be more careful!

Ianto.W. · 14-03-2007, 14:03

That was his way of instilling some self dicipline into you, he must have a sense of humour as these bolts are high tensile, if he gave you a blunt drill you would be at it a long time. Off topic I know, the 'drill' we used was called a jumping bit which you struck with a hammer and spun at after each belt, a smaller version of the stardrill used for 'rawlbolts'

andrewb · 14-03-2007, 16:51

Quote:

Originally Posted by DeShark

I was in quite a rush when I first wrote that and wasn't quite thinking straight. In fact, I was almost talking gibberish. It's hard to explain all this without explaining the structure of the atom, absorption of a photon by an atom, electron excitation, covalent bonding and the effect of an incident (incoming) photon on such a covalent material. Thus I'll have to simplify the model somewhat.

In a typical solar panel (The things haven't changed much since their invention except in the purity of the silicon produced), there is a layer of a semi-conduction material (silicon with impurities embedded). The atoms in this layer share electrons with each other and the lorentz forces (electro-magnetic) between nuclei and electrons will keep the atoms and electrons held together. The electrons can be either "localised" (restricted to move around one or two atoms) or "delocalised" (free to move around the whole structure). (Roughly speaking) When the electrons are delocalised, the material is conductive but when the electrons are localised, the material is an electric insulator. When a metal (conductor) is subjected to incoming photons of high enough energy the electrons are given the energy of the photon which increases their speed enough for them to leave the metal completely (aka The photo-electric effect). In a semi-conductor (such as silicon) the electrons are on the border of conducting and non-conducting.

You could say your solar panel is like Goldilocks. If a photon comes in with too little energy, the electrons are unable to move into a free state. They remain "bound" to the atom and do not conduct. If a photon comes in with too much energy, the energy cannot be given to the electron. The energy is converted to heat. The silicon layer heats up and does not conduct. If however, the energy is "just right", the silicon layer becomes conductive, the electrons can flow freely and an electric current is induced. This amount of energy which is "just right" is known as the "band-gap energy". As I said before, for silicon it's about 1.1 eV (electron-volts). This is infrared light.

I really can't spell it out any more. The bottom line is that your calculator will NOT be activated by light from any source and it is NOT the brightness (or amount measured in lumins) of light falling on the solar panel that will determine at what point the calculator will become operative. It depends on the frequency of the light and how intense *that specific* frequency is.

Very well written, making it easy to understand (although does require some assumed knowledge to fully understand whats going on), but thats understandable because this isn't really the place to be teaching full modules

It backs up my argument very well, which I haven't been able to do as I didn't properly understand why the blue light didn't work, I just knew it didn't. However it's now much clearer to me, and most importantly Jambutty will now fully understand why his calculator fails to work as well under Low Energy lightbulbs of equal brightness!