bLu vs. tLu: IS confirms 65% conversion factor

[Luna]

One last point, taking a bit due to all of your hidden attacks

QUOTE:The ohmic approximation is just plain way off.
Before a certain CPFer attacked me for using the re-rating formulas, I would have thought that they were so well established as to be common

ground here on CPF. But I learned that that was not the case. So I have inserted this post to the thread to support the use of the re-rating

formulas


Ohmic approx was used because you never provided *us* with the current at the baseline until after the fact. You told us the rerated

parameters and that the filament was near mealting as per Willie.

The ohmic approx is sufficient in this case but the both current and voltage measurements would have been better. You finally provided it and

guess what, it was appreciated. It just so happened that my measurements (and approx) yielded a measurement closer to brocks, not your guess.


I even gave the formula for determining the tungsten filament resistance.



T = -1.86(R/R0)^2 + 206.6(R/R0) +118

R= resistance of filament at temp
R0=roomtemp(0 really but no need to freeze it)


When the filament temperature is already in the 2800K+ range and the Tdelta is very low it approachs ohmic behavior . When the gradient is

large, it is classical nonohmic. If you can derive the resitivity at a particular temp, the change in R can be derived via the diffeq at the

new temperature. You provided the temperatures/color temp.



QUOTE: People like PaulW and Ginseng are ingenious and inventive enough to come up with a method for approximating the real output of our

incan mods and all you can do is to try to tear it down. Talking about all the many reasons why it isn't valid, or is only valid in this one

particular case and on and on.

I take it you missed my post last year outlining use of a digital camera,photoshop, ceiling bounce and a light of known output to derive

light box type of lumen estimates. I try to contribute to yah know...

march 9 2005

...I did one step more. I did a ceiling bounce with a white door being photographed in manual mode. I used a p60 with new batteries for

reference, the l2, u2 and u2 + l2.

I did a 25x25 point sample at a point in each picture to derive the rgb. I summed the components and applied a ratio to the known approximate

output results.

P60=1*65lumens=65 lumens (hard math) (22 was the r+g+b score)

L2 rgb score =33 33/22 * 65 = 97.5 lumens
U2 rgb score =41 41/22 * 65 = 121 lumens
u2+l2 rgb score =78 78/22 * 65 = 230 lumens

Of course there is error in the ccd due to the bayer filter and other issues. The system isn't technically sound but is isn't a bad estimation

assuming the p60=65lumens was a good calibration. So the simple test does help to back my claim of the difference between the two.

I'd imagine I can make it work better, including giving spectral results but it was more of a verification. I need to do the same without he

B65 battery and also the 3x123 u2 which seems to give about a 20lumen increase (just a test not a long term burn because I like the u2 and I

only have 3 levels vs 6 when doing this)

[js]

Sorry Luna.

You're right. I suppose I did call you out in mentioning the LuxLuthor thread, and that you were thus more or less obliged to make an appearance here, even though I did say in a POST (not a PM) that I was done with you.

And yes, while sometimes I can carry on an adult conversation, there are other times I fall short.

As for the 100 percent LVR efficiency, I am refering to this from the same SF/M6 thread I linked to above in the "this thread" hyperlink:

So you believe an ohmic "approximation" is not suffient here when dicussing a current a small temperature change. Oh well lets jump to emperical then.

I just measured the MN21 with 2 LG2400s(used a bit but with open terminal voltage of 7.98--full charged normally to 8.32v)

I=5.04
E=6.58

Here I'm getting 33 watt at 6.58volts

So now we now have enough information to used thve rerating formulas and your 6.86v since behand we never had enough info to accomplish this because you rejected Brocks data.

Ir = (Va/Vd)^0.55 * Id

Ir=(6.86/6.58)^.55*5.04

So using my measurements as the baseline and your voltage, that would be 35.38W at 6.86V/5.156A
Using brocks measurements would put your 6.86 at 5.22A, a little closer to 36 watts

Now if you still think that thermistic changes will play an appreciable role, you still can apply ohm law to to determine the resistivity of the tungsten filament.Just compare the approimation assuming ohmic and the rerated ones using your 6.86v and you will notice a mild difference of only 100ma. What is weird is that the rerating given a lower calculated resistance at the higher voltage which doesn't concur with reality.. Nor do my
measurements compare with your farout technique to come up with 4.9 to 5A via assumed L/w, 100% pack utilization and runtime.

PS Gee you are an ass sometimes, with me and AWR etc.... Also the lockups are because of the quote ubb code, I haven't been able to get thru since yesterday because of that

I went to a lot of trouble to make that post wth the "farout" assumption in it, which, by the way is only 2 percent away from the truth, and I did all of this because you asked me questions. And the thanks I got was for you to argue with me over extremely well established re-rating formulas and to belittle my post which attempted to come up with a current draw based on the information I had to hand at the time.

You can say I am an ass if you want, and there are certainly situations where I have made a-hole type posts, but in that thread I was only trying to be helpful and to answer the questions asked of me. And for the record, what I said to you in a POST was the following:

"And you know what else, Luna? I'm done with you. Don't PM me and don't post asking me any questions any more. And I sure as hell won't bother trying to post to any thread you're involved with."

Except of course my own threads, because how can I not be involved with my own threads?

So, speaking of my own threads, let's move on, shall we? To some constructive and helpful discussion.

For starters, I remember reading a lot of stuff about optical coatings in NewBie's Reflector coatings and in the visible range, I remember aluminum being pretty much the best, but it's been quite a while.

Maybe someone can speak more or less authoritatively on this subject for our benefit? NewBie maybe?

[tvodrd]

(Jar- give 'em hell!)

Larry

[andrewwynn]

I have noticed something when doing ceiling bounces.. The RT4 light which is supposed to be aprox. 440L.. actually estimates over 400 TL, so i think there is something to that 65% not being the right factor when considering LEDs.. Has anybody else done some simliar comparisons?

-awr

[NewBie]

(Jar- give 'em hell!)

Larry

Well, I'm a working man, and I've gotta head out early in the morning, so I will try and keep things very brief.

For now, IMHO, the generic 65% is a great way to hit a rough approximation.

If someone wants to use another number, I do feel that an integrating sphere is going to be the only real legitimate way of claiming otherwise.

Don't forget that AR coated lenses range from 0.2 to 2% reflectivity on each surface (front and rear), depending on whether it is a single coat, or a multilayer broad band coat. The skill of the chamber technician will affect the final outcome. You also incur losses in the glass lens, depending on whether it is common soda lime, "water white" (soda lime with reduced iron), borofloat, or various other types of glass. There are also two common types of AR coatings, Magnesium Fluoride and Silicon Dioxide. The Magnesium Fluoride coating typically will have a lower reflection amount, but the Silicon Dioxide is a bit tougher. Usually a good Silicon Dioxide AR coating will look green when done correctly, and you can judge the quality of the Mangesium Fluoride coating, as it should have a purple hue or tint in the reflection. Having the coating thicknesses done just right, means it is centered in the visible band, and you get some reflection on the red side and some off the blue side, with the least in the center (green). Thus the purple hue.

*BUT* AR coatings do not work as well when the light doesn't hit the surface perpendicular. As the angle increases, the percentage of reflection increases very significantly. This is something to take in account for if the diameter of the opening increases without increasing the depth at the same time.

As far as the effect of the rear hole, the reflector focal point would have a good amount of effect. In most reflectors, the bulb itself takes up a considerable portion of that "escape" area anyhow. If that escape area is further filled with a mirror, or even a white ceramic or whatever, it's contribution will be even less. Though one would really have to wonder, if it wasn't directing the light out the front, what real good those few lumens would be. Consider the area of the gap, or the "escape area", it's distance from the filament, create a sphere around the filament at that distance, and compare the area of the sphere to the gap/escape area (and remember not to include the area the bulb itself blocks)...

It would be a pretty trivial task to stick all this into a decent raytracing program and assign all the surface properties, and then re-run it with new propertes. It just takes time, which I do not have at the moment.

The reflector coatings are an important piece of the whole situation. Though I don't know if I'd personally buy just an Enhanced Aluminum, or Enhanced Silver. I'd be more apt to lean towards a protected enhanced aluminum or protected enhanced Silver. I did several posts on these coatings in the 2003-2004 timeframe, complete with quite a few links to references.

Boy, I sure wish the search function still worked, there is an awful lot of wonderful information we built up over the years. These special reflector coatings are nothing new, and we have discussed them several times before.

Unfortunately, standard Vacuum Deposited Aluminum is not quite the same as Enhanced Aluminum, though it usually is better than no coating. Additionally, I've seen multilayer stackups of various materials, that can attain +98% reflectivity, even with the Silicon Dioxide protective overcoat. Think of it kinda like a dichroic reflector, but used to further enhance the coatings even more.

Again, IMHO, the 65% is a *darn* good number to start with, until a given item is actually tested with an integrating sphere. At that point, with real numbers in hand, then one would be able to legitimately claim otherwise for that particular setup.

Oh, and on the ohmic thing. Doesn't the formula only figure for a filament in free space? One would have to consider the contribution of putting it in glass envelope, pumping it full of a gas, and the heat it would contain, as well as the contribution of cooling since there is a gas in there, and the air currents. One might want to also figure in the effect of the stand off wires to the whole situation. I've never seen the source for the formula, nor bothered to look up how it was produced. I'd also figure that how the filament was wound, single turn loop, single turn loop then wrapped in a larger loop, and the proximity of the other turns in the loop, as they'd radiate into each other. Also, something that comes to mind, is the halogen cycle... Now, once you contain all this in another housing, such as a reflector with a cover glass on the front, you in essence have formed yet another thermal containment chamber of sorts.

Just my quick thoughts on things, I really gotta hit the sack now, you guys have a great night, and even a better tomorrow.

[LuxLuthor]

I wish I knew as much about all these technical aspects as those speaking in this topic, but it was interesting reading from all parties....even if I only picked up some of what was being said.

Great topic, even with the

[js]

NewBie,

Awesome post! Was the thread of yours I linked one of the ones you were thinking about?

Larry,

Don't egg me on, man! I'm already too prone to that sort of thing as it is!!!

AWR and everyone else,

I thought it was obvious from my choice of forum for this thread (Incandescent) and from the PaulW threads I linked, and from my initial post, BUT, just to be clear:

***I only know about ican mods and I am only recommending the 65 percent figure as a good rule of thumb for INCAN mods. If anyone got the impression otherwise, I apologize. I have no idea what sort of conversion factor to use when considering LED's and optics or reflectors. No idea whatsoever.

As for the resistance versus temperature of Tungsten, NewBie's comments are right on. That formula is indeed for a bar of Tungsten in free space. First of all, when you coil the filament, the coils mutually radiate into each other and heat each other up, which is why the center-most coil reaches a higher temperature than the ones on the end. Then put the whole thing in a high-pressure fill gas (of any of various compositions) and throw in the halogen cycle and the relationship between CCT and filament resistance is anybody's guess.

And, I have learned from talking with the Carley engineer who designs their lamps, that measuring and determining CCT is not standardized. Welch Allyn, he informs me, always gets significantly higher CCT's from the same lamps than Carley does. You can even see this by checking out their web pages for xenon lamps and halogen/xenon lamps, then compare the range of CCT's with the www.walamp.com webstore specs for the Halogen lamps. (Click on webstore, click on Halogen, then move through the various pages).

I asked the engineer the question that Lurveleven and myself have been wondering about for many months now: "Why make a xenon lamp and NOT add a halogen to the mix to prevent blackening?"

According to someone here on CPF who used to work at a facility that made halogen lamps, he said that if you want to make the most efficient, highest pressure xenon lamp, you can not add any significant trace amount of a halogen because it will corrode the filament supports at the highest pressures. (I think that's a fair paraphrase).

But when I tried to pin this engineer down on the subject he more or less denied that there was any real reason NOT to add a trace amount of a halogen to prevent blackening over time, but only said simply that "it just isn't necessary" in the lower powered xenon lamps because they don't deposit much tungsten on the envelope anyway.

So now I'm no longer sure about the whole issue of xenon vs. xenon/halogen. And in fact, the WA lamps have a krypton fill which you think would mean slightly less efficiency than the xenon, but yet the WA lamps seem to have the highest efficiencies of any of the available halogen lamps out there, even when considering the SureFire lamps as well. Plus they can do them smaller than almost anyone else for a given power.

I am trying to get my hands on some real engineering manuals for lamp physics and design, but they are apparently almost all proprietary internal documents owned by companies like Sylvania and Osram. Still, the Carley engineer said he could maybe put something together for me. I sure have a lot of questions that such a manual could help me answer.

[Luna]

Newbie, hola.

quote: Newbie
As far as the effect of the rear hole, the reflector focal point would have a good amount of effect. In most reflectors, the bulb itself takes
up a considerable portion of that "escape" area anyhow. If that escape area is further filled with a mirror, or even a white ceramic or whatever, it's contribution will be even less. Though one would really have to wonder, if it wasn't directing the light out the front, what real good those few lumens would be. Consider the area of the gap, or the "escape area", it's distance from the filament, create a sphere around the filament at that distance, and compare the area of the sphere to the gap/escape area (and remember not to include the area the bulb itself blocks)...


This is why I think ultimately TIR like optics will be great for incand also. Capturing light from the front and the rear and redirecting it

forward.

The silvering of the bulb might not contribute too much (hard to say since it depends on the envelopes optical characteristics) but is will

help some (just like UCLvsLexan or ProGold on the electrical contact etc). If anything is will help reduce backplane absorption which of

course reduces the warming of the light


So what do you think of my the LED assertionYou alway contribute good, well thought-out information so comments would be appreciated.


(I'll hit the ohmic question in another post)


PS you can do a partial search on google using site:www.candlepowerforums.com and just add any other terms. Be sure to click on the cached

copy. Then do the profile thing to find the whole thread. I do wish the search was working though.

[NewBie]

Can anyone give me approximate reflector dimensions and hole size?
Lamp dimensions for the package, filament, metal base height?
Typical bulb lumens for the bulb?


When I get home tonight, *maybe* I'd have time to model something up, and toss in various surface parameters, and see how the numbers fall out.

Those were not the threads I was thinking of, I was thinking more about the one where I was talking about the losses, as the light travels from the source to the reflector and out, and the other thread where I gave a number of coating reference .pdfs


More info on AR. The multilayer magnesium flouride AR coatings are commonly known as HEA and BBAR. More information on the AR coatings can be found here:
http://www.molalla.net/~leeper/ar_coa~1.pdf

And some generic reflector coatings:
http://www.molalla.net/~leeper/refcoat.pdf

Perkin-Elmer's line was picked up by these folks, and they offer some great reflector coating information and services:
http://www.optiforms.com/4000service...TYscience.html

Remember, take bare aluminum deposited coatings with a grain of salt, as they rapidly deteriorate upon exposure to air...

[Luna]

QUOTE:js***I only know about ican mods and I am only recommending the 65 percent figure as a good rule of thumb for INCAN mods. If anyone got the impression otherwise, I apologize. I have no idea what sort of conversion factor to use when considering LED's and optics or reflectors. No idea whatsoever.


No no no no no. I want criticizing your numbers. I just added the LED bit as a point to ponder.


QUOTE:js
As for the resistance versus temperature of Tungsten, NewBie's comments are right on. That formula is indeed for a bar of Tungsten in free space. First of all, when you coil the filament, the coils mutually radiate into each other and heat each other up, which is why the center-most coil reaches a higher temperature than the ones on the end. Then put the whole thing in a high-pressure fill gas (of any of various compositions) and throw in the halogen cycle and the relationship between CCT and filament resistance is anybody's guess.


If you know the current and voltage (which you measure), you can use ohms law to get the resistance at each level. Compare it at multiple input levels and you can see that it is *fairly* linear over 2800K (until melting)

Just about all conductive surfaces display a nonlinear resistance over a the range of power inputs. Even plain copper wire, it just isnt as pronounced as a tungsten filament. See below link since you don't want to accept my formula (which is by the way for a filament not a bar)


QUOTE:js
relationship between CCT and filament resistance is anybody's guess


CCT correlates well to the filaments temp(IIRC approx 300deg diff in the bulb types we are discussing since hotspots there is a temp gradient involved) . The filament temp directly governs filament resistance though. However, when you said that the data you provided from willie was "with the filament about to melt", we were no longer with CCT but actual temperature. Don't confuse CCT and actual filament temperature as being synonymous. However see below link, they seem to be ok with the concept at sylvania.




http://www.sylvaniaautocatalog.com/n...fila_lamps.htm

"Since the temperature coefficient of resistivity for pure tungsten is relatively constant over the range of lamp temperatures, it provides a convenient means for measuring the average temperature of a filament. "

[js]

Luna,

Please don't bother hitting the ohmic question in another post. Not on my account anyway. OK? Because it really doesn't matter what the resistance of the filament is. You can always find a single voltage and current point and then use the re-rating formulas from there to determine the new current at a different voltage. It's more or less straightforward to measure the current draw of a lamp for a given drive voltage, then you just go from there. I'm not sure why you even needed it back in that "SF/M6" thread because I *DID* right from the get-go give voltage and current values for the MN21. Then you posted this, a couple posts prior to you challenging me on the re-rating formulas:

4.9 to 5.0 amps times 6.8 volts equals 33.3 to 34 watts.

So Brocks measurements are off ?(6.1v 4.9A giving a heated filament resistance of 0.803ohms)

Otherwise wouldn't you be seeing about 5.5A at 6.8V?

The ohmic approximation is never going to be useful. It is always just as easy and more accurate to use the re-rating formulas.

And notice that they do not have a re-rating formula for CCT? That's because the relationship between CCT and V, I, Hrs. of life, and Lumens is not deterministic. It depends on fill gas, filament geometry, envelope size, etc., etc. You can reverse engineer one from the various WA specs, but I suspect that that is probably only approximately valid for their lamps only. Because I know that the fill gas alone can have at least a 100 K effect on the CCT.

As for mirroring the underside of the lamp envelope or the surface of the potting material or support structure, I can only say for sure that you obviously have to make sure not to form a conductive path between the two lamp pins, and also that you will probably introduce some spurious light to the beam, i.e. artifacts. Plus there may be some issues with increasing envelope temperature at the pinch, as well as mating the materials together over such a large range of temperatures. It certainly can be done: I know of an Osram lamp, for example, which is meant to hang down from ceiling lumiaries and its bottom half actually IS a reflector. Pretty neat, really.

But anyway, let's just drop the whole ohmic question, OK? I mean, you aren't saying that it would be BETTER than the re-rating formula for current vs. voltage, are you? If not, then the question is really a dead-end in my opinion, FWIW. But suit yourself I guess.

[js]

For those who would like to have as complete and authoratative a source as I have yet found on Halogen lamps, go to this Osram/Sylvania page and click on the link that says "Engineering Bulletin - Technology and Application - Tungsten Halogen Low Voltage Lamps Display/Optic." And it will open in a pop-up window (these must be enabled) and start Adobe reader. It's a pretty big file so it will take some time to open on slower internet connections, but once you've got it, you can save it to your own hard drive or whatever.

[Luna]

quote JS
And notice that they do not have a re-rating formula for CCT?
See my sylvania link THEY do!



quote JS
The ohmic approximation is never going to be useful. It is always just as easy and more accurate to use the re-rating formulas.

Like said above, It was used in the absence of the necessary information to use the WA that you cannonize. Your reading comprehension is being affected by your anger.



---




BTW, I'm not responding on your behalf alone. This a a community so if you wish to discount my contribution go ahead. I'm posting for others too.

You continue to attack the person not the post. Shall I then? You were wrong on the reflector coating (vac Al <> Enhanced Al). You are wrong on this. You were wrong in the assertion soldering end to end won't cause leakage. etc...

Get over it. This is unproductive. Lets talk so we can all learn something! Set aside your hurt ego. My god man, you are still harboring hate on a post from 2 months ago.

[wquiles]

js - great post. As always, thanks for sharing your experience with us

Will

[bwaites]

Luna,

You continue to do nothing productive or enlightening in this thread.

If you would like to discuss whatever topic you so desire, please have the decency to go start your own thread.

Your posts here have provided NO enhancement, and apart from your constant baiting and sniping do nothing but muddy the intent of the thread.

I, and many others, apparently, since no one else has even responded to your constant harping, see no need for your continued interruptions.

As for js being wrong, I see no where that he was wrong on coatings (I stand corrected by js though I am still missing something), no where that anything about soldering was mentioned. (For your information, several large manufacturers offer end to end soldering at a premium for those wishing the least resistive connection for their battery packs. While Jim has stated that the cause for battery failures in the USL project MIGHT be related to soldering, many unsoldered cells have failed, even those purchased and used individually apart from my project.)

You are right about one thing, this is unproductive! You advised js to get over it, I would ask you to do the same, and take your opinions and thoughts to your own thread.

Finally, I am offended by your invocation of Deity, please refrain from similar use in the future!


Bill

[js]

quote JS
And notice that they do not have a re-rating formula for CCT?
See my sylvania link THEY do!



quote JS
The ohmic approximation is never going to be useful. It is always just as easy and more accurate to use the re-rating formulas.

Like said above, It was used in the absence of the necessary information to use the WA that you cannonize. Your reading comprehension is being affected by your anger.



---




BTW, I'm not responding on your behalf alone. This a a community so if you wish to discount my contribution go ahead. I'm posting for others too.

You continue to attack the person not the post. Shall I then? You were wrong on the reflector coating (vac Al <> Enhanced Al). You are wrong on this. You were wrong in the assertion soldering end to end won't cause leakage. etc...

Get over it. This is unproductive. Lets talk so we can all learn something! Set aside your hurt ego. My god man, you are still harboring hate on a post from 2 months ago.

Luna,

I did get over it. I was responding to your posts and not attacking you or your person. Where did I do that since I said I was sorry and "got over it"? I'm quite sure that I didn't.

And now I really and trully have to seriously doubt that you aren't intentionally trying to make me angry.

Please stop this.

*****

First off, I posted what I did before I had seen your post #40.

Second, it was relevant because you keep claiming that you needed the ohmic approximation because of the absense of necessary information. Not so. And it also points out that the ohmic approximation which you used over the 6.1 to 6.8 volt range was off by a non-trivial amount.

The example I gave above of the WA 1111 at 6.0 volts vs. at 7.2 volts *is within the range which you claim is approximately linear. The CCT at 6.0 volts is 3325 K, and the CCT at 7.2 volts is probably close to 3500 K. Yet the ohmic approximation yields 4.0 amps, and the re-rating formulas yield 3.70 amps. That is a significant difference.

As for the difference between CCT and actual filament temperature, I am well aware of it and have mentioned it a number of times before this thread. The CCT can be approximately 60-80 K higher than actual filament temperature in some cases.

What I said, however, was that the relationship between CCT and filament resistance was anybody's guess. The resistance of the filament is primarily determined by its thickness, in fact. The relationship between CCT and filament temperature is pretty well established, but does depend on a few additional factors, such as the fill gas, for example.

The relationship between CCT and efficiency IS known, however. The so-called "law threes" tells us that at 3330 K the efficiency of a halogen lamp will be 30 L/W, and that for each 100 K increase or decrease, that will change by 3 L/W, if we stay close to 3330 K.

And you keep mentioning that I said that at 6.8 volts Willie said that the filament was near its melting point. Could you please provide the link to that post, because I'm pretty sure that you're misquoting me.

But either way, what Willie actually said to me, was that the MN21 could safely be driven to 6.8 volts and that it was nice and white there, but that it could be pushed even more to 7.0 volts. However, at 7.0 volts it was pretty "smokin' " and was likely to have a very short life. And at 7.2 volts was right near the melting point.

For flashlights, you really can't go much higher than a CCT of 3400 or so because the filaments become to fragile as they approach their ultimate operating temperature. And this is completely setting aside the subject of soft-start and so on. So when I said that 6.8 volts was as high as you wanted to go (if that's what I said) I meant that it was the safest upper drive voltage, and not the point at which the filament would melt.

***

On another note, I never said you couldn't post here about whatever you wanted. I just ASKED if we could drop the whole ohmic question, but in the end said "suit yourself."

You think you are posting "for others"? I wonder what others would say to that?

You say I was "wrong" about end-to-end soldering? Yet you don't mention the fact that this was for the CPB 1650's only, and that it is my considered opinion that these cells have poor quality or insufficient seals. They leak and die all by themselves without any help from my soldering iron. Other AA and A cell packs I have soldered are all fine. All 100+ of them.

But let's get personal here at least one more time, shall we?

You don't really know me, Luna. You don't know that I was reading your posts in anger. Because, in fact, I wasn't. When I said I was sorry and let the whole thing go, I was no longer angry.

You question my maturity and ability to communicate like an adult. Fine. I don't know what's up with you, Luna, but something is. I wish you would go figure it out and come back with some positive energy and contributions, for your sake and everyone elses.

Honestly, I really shouldn't even be bothering to defend myself here. I believe that my credentials and accomplishments speak for themselves. Anyone can check out the links in my sigline and see this. Yet you are ever so quick to assume that I don't even know the difference between CCT and actual filament temperature. You have no respect for me, Luna.

Stop attacking me. Stop trying to make me angry. And stop trying to defend the notion that a filament's resistance is a constant over any significant range of voltage.

[js]

Oh, and Luna,

Yes, I certainly WAS wrong about the reflector coating issue. I obviously admitted this when I asked if NewBie or someone else could say something authoratative regarding the coatings. I've been wrong about a great many things in my various posts here on CPF.

But that doesn't mean I am wrong about any one particular thing, or that when I qualify something and retract part of what I said earlier, that I am admitting to being wrong about the whole issue. I didn't need to ressurrect that thread on end-to-end soldering and mention the likely possibility that the soldering was causing the leaking USL pack failures, but I did. I did it because it was the right thing to do, because part of what I had said I now found needed qualification.

But for someone to then go ahead and grab that peice of good will and use it as a club to beat me with, . . .well, that's just not very friendly, is it?

[js]

Everyone else,

If you have constructive (or otherwise) criticism and advice or comments or anything at all for me in regards to this interchange between myself and Luna, I am formally inviting you to send it my way via PM. I am aware that it is very hard if not impossible to get an objective and unbaised view of one's own actions in any given situation. If people of this community find me to tyrannical or offensive or aggressive and want to let me know about it so I can improve myself, I honestly want to hear about it. Let me know. I am willing to edit or delete any or all of my part of these interchanges with Luna if it will help matters.

I wish to be more positive and friendly and civil and helpful than I have been in the past. And in particular I'd like to apologize to AWR for my early posts about his LDO hotwire driver. They were out of line. As well as some other posts. I am sorry and I apologize and will do better in the future.

So, on that note, I'd like to bring up a topic for discussion:

The difference in relative transimission efficiencies of axial vs. transverse filaments in parabolic reflectors.

My immediate thoughts on the matter are that the axial radiates primarily perpendicular to the axis of the reflector, and thus will have less light that just goes directly out the front of the reflector. However, it will also not have light (or very little) that goes directly backwards towards the bore hole and potting material or bi-pin socket, or whatever.

So does anyone have any thoughts on this?

[Luna]

Quote JS
What I said, however, was that the relationship between CCT and filament resistance was anybody's guess. The resistance of the filament is primarily determined by its thickness, in fact.


What? Have not heard of the transitive rule? If
CCT->FilamentTemp
FilamentTemp->resistance

CCT-> ???
Guess what?


...
Oh yeah, you are pretty close "The resistance of the filament is primarily determined by its thickness, in fact" You just forgot the big variable in filament design, length

This is what we learned in first semester EE (or eng physics, its been a while): resistance = resistivity × length / area



Quote JS
The relationship between CCT and filament temperature is pretty well established, does depend on a few additional factors, such as the fill gas, for example.

Where do you get that from? Gas fill alters resistance?

PS, on the CCT-> Temp. The 'around 300' comes from K->C conversion + variable . Pretty darn close.



Anyways, my ohmic approx matched brock's number not yours. So who is right? Don't confuse my ohmic approx with meaning constant though. I calced the resistance using know info an applied and used linear extrapolation to get the resitance at the other point. I said it is closely linear, not constant at hightemps.
..cut..

[u]bwaites[/b], He was wrong and Jar corrected him too on the reflector coating bit.

Tell me one thing I was wrong about in this thread?

You always come to JS defense why not address the technical and leave the personal out of it. I was called out I bit on the bait.

I think I have contributed quite a bit of information in this thread. Check out the links formulas. You have only done a little bit of backpatting and atttack my posts.


...
Inspite of the argument, this thread is generating a good deal of information for others. Once again, lets talk about this , not prior arguments. I will only address the technical issues from this point on in this thread. My statements all have been mentioned here before, I'm not backpeddling a bit

[Luna]

JS, great start to productive discussion


The difference in relative transimission efficiencies of axial vs. transverse filaments in parabolic reflectors.

My immediate thoughts on the matter are that the axial radiates primarily perpendicular to the axis of the reflector, and thus will have less light that just goes directly out the front of the reflector. However, it will also not have light (or very little) that goes directly backwards towards the bore hole and potting material or bi-pin socket, or whatever.


My initial thought/guess woud be you are correct but the gains made could be offset by loss of light (uncolminated) due to more of the filament being up higher and outside of the optimal focal point. A deeper reflector would be necessary to reap the optimal benefits of an axial bulb

[js]

Luna,

Yes. I was justing about to post that I misunderstood you when you said resistance was "linear" over a range, and was reading "constant". Yes. The filament resistance is approximately linear over the useful range of CCT's. Sorry about the misunderstanding.

Yes, I have heard of the transitive rule.

I agree with the CCT => Filament temp, but disagree with the filament temp => resistance. Not true.

As for filament resistance, yes, I did leave out length. I was typing in a hurry and forgot that part. I know how to figure resisitance from geometry and resistivity. The more important facts about filament geometry and optical/electrical characteristics are that the voltage of the filament is proportional to length and that the current is proportional to thickness, all other factors being equal. This is what I was thinking of when I mentioned length as an important parameter.

As for CCT and filament temp and fill gas, using a xenon fill gas will reduce the rate of vaporization of the filament. A reduced rate of vaporization can be used to increase lamp life, or increase filament temp. Thus fill gas can affect CCT.

[bwaites]

Luna,

I will not rise to your bait and comment on personal attacks.

However, addressing only your points, if you actually had anything new and worthwhile to point out, I would be more than happy to congratulate you for it, however, nothing you have said here has forwarded the knowledge base at all. As you state, everything you have stated here you have stated elsewhere, fine. By your own admission, all you are doing is restating OLD arguments. BE done with it!

This thread was started as a comment on the success of subjective measurements and estimate vs. objective measurement of the output of lamps/lamp assemblies.

That was it's intent and that is what the thread topic is.

If you cannot stay on that topic, (and nowhere does ohmic approximation enter into that topic, nor does anything else NEW that you have posted) please have the decency, as I asked before, to start your own thread.

I, for one, have just about decided that CPF is useless anymore, because every single serious discussion digresses into this kind of confrontation, every attempted good deed is punished.

There always seems to be someone who wants to argue the most basic points, complain that they were mislead, and generally it seems to be someone who has not ever advanced a new idea on their own, never created a new light, never faced the real world problems associated with actually DOING something versus arguing and complaining about what others are doing.

As one long time (and VERY respected) member pointed out last night in a private conversation, credibility is earned by DOING, and everyone on the board knows where the credibility belongs here.

Bill

[Luna]

Luna,
nowhere does ohmic approximation enter into that topic, Bill

My friend, I didn't bring up the ohmic topic, I responded.

[Luna]

JSI agree with the CCT => Filament temp, but disagree with the filament temp => resistance. Not true.

See the link I provided here is a quote:

"Since the temperature coefficient of resistivity for pure tungsten is relatively constant over the range of lamp temperatures, it provides a convenient means for measuring the average temperature of a filament. "



here is the formula list

http://www.sylvaniaautocatalog.com/n..._equations.gif


As for the fill: Since temp is given it matters not if the environment is air, water, 100bar fill or oil. The fill just give longevity to to the specs, it cannot affect the resistance unless it is a conductive

[Kiessling]

Gentlemen ... regardless of who started it, who is right and wrong ... PLEASE stop this non-productive war !
This thread is one of those treasure chests filled with info that can outlast the thread's active life by far, and I would *really* hate to see it die from bickering and mud slinging.
PLEASE ... calm down, step back, and reboot with "the art" in mind.
Thank you.
bernhard

EDIT: non-compliance will have consequences.

[js]

Luna,

There are some very subtle differences being thrown around here. Let's stop arguing and start trying to understand them, OK?

The CCT of the filament is the correlated color temperature. This is the temperature of a true black body whose radiation curve is closest to the radiation curve of the object under consideration. The fact that the CCT is HIGHER than the real temperature means that the tungsten filament is a BETTER radiator at higher temperatures than a theoretical black body radiator.

Now, filament temperature is not well defined, because the temperature of the filament is a function of the position along the filament, and the winding geometry of the filament. What do we mean by filament temperature? The temperature of the hottest point? The spatial average temperature? Or what?

I honestly don't know what is used for determining actual filament temperature or how in practice it is measured. These would be useful things to determine.

But in any case, if the temperature varies with position along the filament, and winding geometry, then does it not follow that the resistivity is also a function of position and winding geometry (number of coils, spacing, diameter of coils, shape of coils, etc.)? If so then wouldn't that also mean that the simple Physics 101 formula for determining total resistance would also become dependent on these factors?

I think this is so.

Finally, the fill gas has a role to play in these things as well. Take a look at page 7 of the "Tungsten Halogen Low Voltage Photo Optics" Osram publication. They say there that "The reduced rate of vaporization of the filament [due to using xenon fill gas instead of something else] can be used to . . . increase the luminous efficiency and color temperature by raising the temperature of the filament."

Raising the temperature of the tungsten and increasing its efficiency would mean more light for a given power. That much I can tell you. But how this relates to applied voltage and current draw, I can not say. Raising the temperature of a free bar of tunsten would necessarily increase its resistance. True. But as for a filament in a high pressure gas, I wouldn't know.

As for the ohmic approximation, you are well within your rights to bring it up and discuss it. I brought it up first. That's fine. But I have an honest, non-offensive, question for you:

Could you tell me why we would want or need to use an ohmic approximation that is linear with temperature? When would it come into play for us as modders, or how can it add to our understanding of incandescent lamps?

As for CCT, I didn't mean to say that one couldn't re-rate CCT based on knowing an applied voltage and a design voltage and design CCT at this voltage. What I said was that you cannot accurately determine a lamps CCT from its voltage, current, lumens output, and life rating. If only because the use or non-use of a xenon fill gas affects these things, and most probably other factors as well, such as mutual self heating of filament coils.

So, BTW, the re-rating formula for CCT which Luna is talking about is this:

CCT_applied=(Va/Vd)^0.42*CCT_design.

And it will re-rate a lamp with a known CCT. But it is useless if you don't already know the CCT.

Luna, perhaps I missed an earlier link that had a way to calculate CCT from other variables.

[js]

Bernhard,

Right there with you. And I would ask that everyone else please focus on only the subject matter being discussed and disregard the perceived tone or intentions of the poster. Luna and I have agreed via PM's to do this. Wouldn't you all please join us in this endeavor.

Thank you for your cooperation, especially as it will prevent any chance of my thread being closed. I think it will end up having value even after the active discussion has ended.

[Luna]

JS, I'm rushin out of the office right now but I will hit this right now:

"Now, filament temperature is not well defined, because the temperature of the filament is a function of the position along the filament, and the winding geometry of the filament. What do we mean by filament temperature? The temperature of the hottest point? The spatial average temperature? Or what?"

In the PDF you posted, they have a good section on it (graph and table). They use average filament temp in K. Do remember to Kelvin to C translation


...

"Finally, the fill gas has a role to play in these things as well. Take a look at page 7 of the "Tungsten Halogen Low Voltage Photo Optics" Osram publication. They say there that "The reduced rate of vaporization of the filament [due to using xenon fill gas instead of something else] can be used to . . . increase the luminous efficiency and color temperature by raising the temperature of the filament."

That just simply means you can burn it hotter before the tungsten boils off, self collapses. There is no other magic involved. It doesn't affect the resistance of the filament. That is an attribute of material, not the environment.

[js]

Luna,

As entertaining and fun as this may be for you, it isn't for me, and I would guess that it's not for anyone else who WAS following this thread (if they still are). I specifically edited this post to remove arguments I made because this thread is still not moving in the direction I would like, nor is it motivated by the spirit it should be.

So how about this, you win, alright?

Filament temp and CCT are both uniquely and completely determined by a certain definition of average resistance and/or resistivity of the filament.

Let's agree that you are right about this. So,

1. Please link to or post the formula for R vs. CCT.

and

2. Tell us all why we as CPFers and/or modders and incan afficionados can find this to be useful.

For example, consider a high voltage, low current lamp. The resistance of the filament by definition is V/I, of course, but what is the CCT? How does CCT relate to other parameters of this lamp? The filament would be long and thin, yes? How long? How thin?

Next consider the WA 1160, a low voltage, high current lamp, and answer the same questions, if you would.

Take us all on a journey! I would love to know more about lamp design. Tell us how you would design a lamp. What steps you would take, at least from a theoretical point of view.

And if you could discuss the Osram 62138 vs. the 64440 IRC, both 12 volt lamps, one 25 hrs of life, the other 4,000 hours. One filament short and thick, the other much, much longer and thinner, then that would be great as well. And an explanation of how the IRC coating improves efficiency would be appreciated.

I had planned on talking about some of these things myself at some point in this thread or somewhere else, but I figure that instead of us arguing about things, I will just let you lead the discussion since you seem to me to be quite sure of your knowledge and competence.

I'm not being ironic here. I want you to clarify and explain all of these things. I no longer want to hear about how I am wrong. Rather I want to hear all about how you are right.

Seriously. I can host pics for you if need be.

[tvodrd]

Jim,

If my short post offended you, I apologise. I remembered some very informative posts Jar had made wrt reflector efficiency. It was a real good start to the missing 35% out the window. The post was meant to encourage him to chime in.

Larry