I have thought about presenting myself for some days now, being afraid that it would be not so interresting for the majority of members, but I got an idea or a viewpoint that I would like to share (look last in this post).
I may be a candidate to being the oldest member here as I got my batchelor degree in electronics back in 1969. For 31 years I worked in the Philips koncern developing measuring instruments for television industry and broadcast. The widespread testpattern for broadcast (that with a big circle with colourbar, definition lines, station caption and outside that bone-shaped coloured fields on grey background with grid lines) is one of my doings, of course together with the others in the development team. Austria was the first country to use our pattern back in 1970.
After Philips I have spent 9 years in a light & optics firm developing measuring gear based on optical principles.
Back from the 1970's I have been fascinated by rechargeable batteries and have since then had a collection of between 30 to 50 of the AA size, exchanging them for newer types when they got tired (5 to 7 years). Most of the time they used to lay on a shelf, waiting to be recharged as I had not really a use for so many (that have changed with the magnificent Eneloop). I remember buying 10 of the first Varta 1200 mAh NiMH batteries, just developed, which was $9,17 a piece (Calculated at the present $ exchange rate).
I made a couple of small, simple chargers for 4xAA but in 1992 I got an idea and during a vacation with my wife on Samos, Greece, I developed (with pencil and paper) a microprocessor controlled 4xAA charger. (Sorry, wife, if I had a distant look in my eyes at that time, I hope you did'nt notice).
The charger happened to be a success and is even today my preferred, safer charger. I also use an Ansmann Energy 8 and a La Crosse BC-900 but they have both fried some NiMH batteries that did not signal with a decent minus delta V which can happen when the battery is not used frequently, for instance new batteries. My own charger uses zero delta V termination so it never fries a battery. If a commercial charger with clean zero delta V termination can be found I'm in for one.
I also think that the slightly early termination with zero delta V is good for the batteries.
In my country we have a department store that sells cheep tools from the far east. About a year ago they introduced some nice looking aluminum lights with 1W and 3W Cree leds. This was the first time they had something with powerLEDS. Especially interesting was a 3xAAA, front clickie, 143mm by 35mm with XR-E ($36) and a 2xAA, rear clickie, 153mm by 27mm with XR-C ($33). The Bin's are unknown, but has a beatifull, neutral colour (about 4-5000K, I guess).
When they came on sale for $22 and $18 I bought a couple and now I was hooked!.
I began reading at Cree's place and "the other place" and was very disappointed when I saw the prices for lights.
Then I suddently stumbled over BLF in mid-september and read day out and day in (sorry wife, again!). I must say that I really learned a lot, I ate Don's measurements raw and of course I ordered a flashlight! Trustfire WF-502B with XP-G R5 1-mode and modded it to 3-mode just as brted intended in his post juni,12'th. I did not know that with $17,25 I was way over the no-tax limit for our country which is $14,60 (present rate), but with the defensive value-marking from DX it arrived with no problems.
If I buy anything from outside the EU which cost over $14,60 (without postage) I have to pay VAT which is 25% of the price including postage and a fee to the PO of $29. That is tripple the price all in all. So you see I really am a Budget Buyer. With the BLF Mr.Lite-must-have I simply had to take the chance...
Also I am heavily dependent of coupons, I surf regulaly for new ones.
Since September I have gone crazy (according to my wife) and bought 5 more lights. And 9 more are on their way.
I have also bought some Li-Ion batteries. I put a 18500 in the first 3W 3xAAA light and got 120 of "MyLumens". Thats nice!. The 1W 2xAA give me 35 "MyLumens" on NiMH.
Yes, I made a milk-carton lightbox like the one I saw (where was it now..). I measure with a Luxmeter and calibrate with a $50 Zebralight H50, thanks to Don I had to buy it!. Using that I could easily be 15% off but for comparisons it is fine.
It is very tempting to mod when a new bin is available. I have met the viewpoint some place in BLF that it takes a lot more than just a new bin of about 7% increase in light to actually see a difference. You can certainly measure the improvement but may be disappointed of the visually result. To clearify for myself what the difference between two outputs means, that could be the Lumens count from Don's table, I take the logarithm with base 2 of the two values. That gives me an output score 0 through 10 (or more) for each light which are much more in line with the perception of the light.
1024 lumen evaluates to score 10
512 to score 9
256 to score 8
128 to score 7
64 to score 6
and so on...
Take for example a light with 100 lumen output (measured) which gives a score of 6,6.
Now you use a lot of time and money to mod it and get 107 lumen and a disappointing score of 6,7!
Another example: How much dimmer is a light of 50 lumen than that of 100 lumen.
The first have a score of 5,6 the latter 6,6 so apparently you lost only 1,0/6,6= 15% light.
Don, could it be an idea to incorporate such a score figure in your tables?
That could help people being more happy with their "smaller" output lights.
Time to wake up! and take care.
It would certainly be easy to do this - I've just put that on the sheet. It makes more sense to me to take the base 2 logarithm of the lux measurement rather than the derived lumen estimate. But I could easily be persuaded otherwise.
It gives me a range from about 2 - 1550 lumens which works out as a score between 3.6 and 13
And good to have you here sixty545.
In 1969 I was 9 years old...
Aloha and welcome to BLF sixty545!
I guess this means that Don isn't the oldest around here anymore. :bigsmile:
I will try to persuade You:
Using Lux instead of Lumens preserves the idea as they are proportional. But it will bring us out of comparison possibilities. I know that you have a faktor for estimating Lumens from Lux but my lightbox is constructed so that I can read Lumens directly from the luxmeter in the x100 range (100 Lux happens to be 1 Lumen in my box). So you can see that we have the same Lumen value but different Lux value.
A warm welcome!
Welcome! Glad to have you here. I hope you were happy with the 502B and mod. That's one of my best lights.
Thanks for the welcomes!
Yes brted, the 502B is very fine with the 3 mode driver. I like the big hotspot.
It is a little greenish but that is common for R5, I think. I got an Ultrafire C3 R5 and it was also greenish.
I thought a little more about it. You can freely add a constant to all score values to fabricate a suitable range for the score figure. That is equivalent to multiply all Lux- or all Lumen-values with a factor K:
score = log2(K * Lux_or_Lumens) = log2(K) + log2(Lux_or_Lumens).
log2(K) is that constant.
Whatever the scale is (from -2 to 10 or from 1 to 13 or other) there will always be a factor 2 in light between score steps.
To make it simple for others with a lightbox to also calculate the score I would recommend using Lumens as in:
score = 2.4 + log2(Lumens).
That will give you your scale 3.4 to 13 for 2 to 1550 Lumens and others can do the same calculation with this formula.
Hope you find a good scale formula and thanks for the interrest in my idea. I hope that some will find it usable.
OK - I'll do it for lumens as well. Not a problem.
Done - scale goes from 1.1 - 10.6
But this does depend on the calibration and we used different lights. My Zebralight claims a flat 66 lumens on high so will try and see how the numbers work against it as a calibration source. Ideally, I'd work out a polynomial with multiple calibration points but I'm quite glad I last had to do that in 1982.
Spent three months analysing sewage samples for cadmium using wet methods - basically fiddling with the pH and dropping stuff in and out of solution with potassium cyanide.
Extracting the resultant horrible stuff into chloroform in a lab with inadequate ventilation. Chloroform intoxication is unpleasant. So is hydrogen cyanide intoxication but it has less of a hangover and is probably marginally less bad for you.
Reacting the result with some reagent that took me weeks to make and purify.
Then measuring the resultant bluish colour in a spectrophotometer.
My blanks stayed blank and my standards gave nice clean numbers like they were supposed to. Unfortunately they were done in the same time sequence as the concentration level.
Ran all the samples, ran the error stats. they were far too good. I'd have been happy with 10%, ecstatic with 5%. I got 2%.
Went to my boss saying, I don't believe this. Handed him the lab notebooks, he ran the stats. He came up with 2% as well. Phoned a manager who was a PhD in this stuff - sent him the lab notebooks.
He didn't believe it either. So he ran the numbers (Nobody had computers then and everyone, myself included, thought there was an arithmetical error somewhere in the stats.)
And got 2% errors.
Since there was going to be a criminal prosecution over these analyses (It looked like an electroplater was taking really nasty liquid waste loaded with cadmium and cyanide and pumping it down a residential drain. You can get 3 years in jail for that.) the results got sent for independent analysis using a different (and far better) method. Their results made mine look like random numbers
After a lot of screaming and hair pulling and pointless redoing of hundreds of samples it turned out that the spectrophotometer gave readings in the blue that depended only on how long it had been turned on for, not what was in the beam. It worked fine down to about 500nm wavelength, but below that things got seriously messed up. And it had just been re-calibrated by the manufacturer a month before I started this nightmare. They'd calibrated it at about 560nm and it was fine there. I may add that the calibration cost more than I got paid for those three months.
I've always hated calibrating stuff since then. And been very, very suspicious of my own results.
Each half number range puts lights in the same class of output. Maybe double it so that each whole number range is comparable output. So any light in the range 3.0 - 3.9 is of comparable output to any other. That gives an output number of 2.2 - 21.2.
Since visual perception is logarithmic, this approach makes a lot of sense to me - at least now that we have computers to do the boring arithmetical stuff.
It also makes it immediately obvious what sort of output class a light is in.
I was tempted to say Jesus!
There is a strong analogy to our measurements on flashlights on high mode while the LED is heating up!. I can follow you on the photospectrometer part but not quite on the chemics, but is really sounds toxic! So they calibrated it at green and you used it at blue where it was drifting like our flashlights.
Welcome to a great site.........
Basically yes - the sensor seemed to measure its temperature at that wavelength (Or maybe milliseconds since it was switched on) rather than the intensity of colour of the cadmium/cyanide/horrible reagent compound which is what I cared about knowing. The machine certainly was supposed to correct for temperature - and maybe it did - just not for me.
What I was doing as reading the intensity of the reference beam which didn't go through the sample minus the value of the beam that had been through the sample - the difference was essentially the concentration of cadmium in the sample.
Cadmium does Bad Things to living organisms which is why I wasted 3 months testing for it.
Actually electronics were just beginning to come into affordable lab equipment - like the wonderful sampler that could for the first time do amazingly clever stuff. Unfortunately it would only work it if someone was watching it. Like many of the people I worked with in that lab.
Any chemist gets used to working with very dangerous stuff. As long as you know what you are doing, it is safe enough. Actually, cyanide is not as dangerous as most people think - the fatal dose is actually a visible quantity. Pure nicotine is a lot more poisonous as is methylmercury which is not something I want to be in the same building as. A chemistry blogger has a wonderful list of things he won't work with as they have too much "personality".
I must remember not to put those cadmium treated climate screws in my mouth any more -lol
Derek Lowe is fun to read as he personalises the bad toxic killers. Isocyanides among others. I will study his blog further when I have rested.
For the calibration with the H50 I "adjusted" my light box so I could read 6500 lux on high (display= 65). As I think that this box is too small and narrow to treat the wide angled light correct, I have no intention of publishing my measurements. They are just for my own use. I might make a bigger box some day.
Damned that I did not aquired an integrating sphere from my last job before I retired, we made them for measuring roadmarkings. But that was before I went flashaholic. But again, they were BIG, about 1/2 meter diameter (not welcome at home).
Don, can you do the same for Lux reading so the two (output vs throw) are more easily comparable using the log scale?
A difference column might also be useful.
For example, a lot of these lights have lux - lum ~= 4-5 in log2 scale.
But MRV is ~=7.
Hello sixty545, welcome to BLF! We're glad to have you here, please enjoy your time here.
Sounds all too familar :D
I do believe I have a fellow DK citizen is the forum!
I presume you mean the throw numbers where i have them?
I'm not sure I'm clear on what you want.
I've done the same for the Log base 2 throw numbers and doubled them as I've done for the lumens numbers.
I'm not sure I'm clear on what you want.
For the lux log scale, I think there are two main uses. One is just make the throw of light also scaled to how our eyes percieve it, same as for lumens. The second, more insightful use, is that if you take the difference between the two, it should tell you the the "throw-iness" of the light (similar to the ratio between the two before log). Ie. the sample results of the subtraction above for the MRV should hold even if you somehow doubled or halfed the light from the led.
So basically that number (~7 for a nice thrower like the MRV) becomes an inherent property of the design of the light (technically, mostly the reflector and centering), nicely seperated from whatever emitter bin/battery/driver combo happened to be used with it. Better thrower designs will necessarily have a bigger number, so if you want the best thrower (all other things being equal, which may well be true given the random bins/drivers people tend to get), you pick the light with the biggest number for log2(lux) - log2(lumens). In practice, a 7 there will almost always throw better than a 5 even if you got a total dud.
BTW, is there a reason for doubling the numbers? I suppose you can scale it to anything for convenience and it doesn't matter, but why *2 specifically?
Thanks Don, I thave seen your table and I think it works!
The score column really makes it easy to compare light output (at least for me). Where you are missing a value you could ask the spreadsheet to put in a zero (I am sure that you already thought of that). The column L2 I can understand is your bin, but should'nt it be whole figures?
You are quite right, tak for velkomsten, You have most certainly guessed that my first power LED lights are from Harald Nyborg. The 3W model has direct drive, a single 0.68 Ohm resistor. When I changed from 3xAA (4,5V) to 18500 (max 4,2V) I parallelled the resistor with another resistor 1,2 Ohm and it can certainly shine. I have used it to hunt spiders in all corners of my house with a high voltage racket that fries the beasts. Normally I do not hurt any animal but I was invaded by these long-legged spiders with their spindle everywhere for over 5 years.