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Inexpensive LUX meter from China to measure your bike lamp's output

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Old February 26th 18, 06:32 AM posted to rec.bicycles.tech
Andre Jute[_2_]
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Posts: 8,572
Default Inexpensive LUX meter from China to measure your bike lamp's output

On Sunday, February 25, 2018 at 3:10:41 AM UTC, Jeff Liebermann wrote:
On Fri, 23 Feb 2018 14:28:26 -0800 (PST), Andre Jute wrote:

It's anyway pretty rare outside the pure sciences that a single
measure of benefit or goodness (or badness) will tell you
everything you need know. Practical applications just don't
work like that.

That's easy to remedy. Permit me to introduce my "Index of
Conformity(tm)" which measures how well someone agrees with my
reference opinion, which I hereby declare to be optimum and a de facto
standard. 100 is total agreement and 0 is total disagreement. By
comparing your prejudices, biases, impressions, and premature
conclusions with my optimum reference standard, as single number can
be used to measure your conformity to my ideal. For example, if you
were to purchase or build a bicycle lighting system exactly like mine:
your system would be rated at 100. Any variations from this will
result in a lower score.

That's worthy of Sheldon!

From a strictly
mathematical, theoretical statistical viewpoint, the number of
assumptions and guesstimates from experience one is required
to make even in a well-studied field can be disturbing, even
discouraging to the newbie until he discovers that applied
statistics is an art form for high rollers and the super-confident.

85.46% of all statistics are made up for the benefit of the current
audience. I'm fortunate in never having had to make a major financial
decision solely on the basis of statistics.

Sure, you generally know what you will advise the client to do before his team has finished their presentation of their problem. But look at it from their viewpoint. The sort of client who can afford people like me is only in very rare cases the owner of the business, and then he's rich because he's dead cautious but very focussed until the moment comes to strike. The much more common case is that they are rolling the dice with shareholders' money, so they hire you because they know you're likely to come up with the answer they want but also because, when it goes cockamamie, they have the out, "We hired the best specialists and this was their plan. We've already stopped retaining them, so they can't mislead us again." It's just a risk you run; you get blamed whether they followed your advice or not; if you're smart, you impose a fat upfront premium for being a scapegoat some future day. The problem that arises, at which point you'd better be as good as your reputation, and possessed of brass balls besides because this is for your seven-figure job and most likely for your career, is when the numbers of a competent and honest study go against the grain of the client's experience and your own experience, when you have to persuade the client to go against his instincts. In cases like that it is smart first to farm out smaller validation studies to your competitors without telling them who the client is and without telling them what you've already discovered, so that they can't suffer from your unknown preconception, if any. That's a hall of mirrors, and it can be pricey and time-consuming: "Mr Ford, we know your executives are impatient to GO, but impatience could result in you staring an Edsel moment in the face."


Opinions vary:
- Frank wants brightness limited to avoid blinding oncoming motorists.
- SMS wants some upwards spill to help see overhanging branches.
- You seem to want (not sure) more beamwidth to help see the roadside.

I want sidespill to see the road verge, which on Irish lanes, where I ride, is often broken up and right next to the ditch full of icy slurry (liquid cow****) or a thorny gorse hedge. I want the cutoff higher so I can see overhead branches before they knock me off my bike; on my bike, my head rises above Range Rover height; I would welcome a dimming feature on the lamp so oncoming motorists aren't unintentionally blinded. And in addition, the higher cutoff will let me see road and especially stop signs at crossroads from well back, which is absolutely essential. Furthermore, I want a high-power blinking lamp, front and rear, for daylight use; for that purpose, I currently use additional lamps front and rear, but resent having to change batteries on them because of the stupidity of German legislators.

- NASA wants even lighting and no hot spot so that press release
photos look good.
- Barry wants only the forward facing area to be considered (beam
lumens), discarding the dim spillage as useless light.

Barry should learn to a) keep his mouth shut and b) work with a competent marketer who won't give so many hostages to the egotrippers on the net. He's a prime example of why professional communicators want to lock up techies, and even more inventors, in a cage in a back room where they can't undermine their brilliance by opening their mouths in public. To channel Bill Gates, that "dim spillage" is not a bug, it's a feature that he wants to emphasize. (Notice that I think his light is very likely good -- NASA doesn't hire dumb engineers; I'm talking only about his counterproductive "promotion".)

- I want megalumens so I can set fire to the riders clothes ahead of
me. I also want megalumens because my principle use is "be seen"
lighting, which means I want to get the attention of motorists.

One number is definitely not going to be enough for a buy decision
from the above picky customers. The way I look at the problem is that
it's my light and I'll do with it what I find useful. If I want any
of the aforementioned illuminating aberrations, I'll do it somehow. If
conditions or ambient lighting changes, I want the ability to adjust
the intensity and beam pattern for those conditions. One number is
not going to work even for my buy (or make) decision.

Exactly my attitude. In years gone by I built my own lamps from entirely free (whatever that cramped idiot Krygowski says) information page Scharfie kept. The best were MR11 lamps glued into Roma tomato paste cans, which they fitted exactly. I had two, one pointed at the ground road in front of me to see the verge and the potholes, one pointed only slightly downwards with good throw for fast descents with enough overspill to see low-flying branches. The "fast" lamp was on a switch under my thumb, so that an oncoming car would see the light dim the moment I saw his lights. It was driven by a water-bottle-sized battery pack left over from a commercial lamp system I found inadequate. I rode with Scharfie's lamps (MR11 and MR16) for years until I discovered hub dynamos.

What I'm trying to do is
provide the GUM (great unwashed masses) a means of verifying that the
stated lumens are something close to manufacturers claims. I believe
I've done that successfully.

GUM. I've always thought it ironic that the best and most exclusive department store in Russia under the Soviets was named for the Great Unwashed Masses.

Old February 26th 18, 06:50 AM posted to rec.bicycles.tech
Andre Jute[_2_]
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Posts: 8,572
Default Inexpensive LUX meter from China to measure your bike lamp's output

On Sunday, February 25, 2018 at 8:35:22 PM UTC, jbeattie wrote:
You would think that with modern technology, you could come up with a highly efficient dyno/light with a shaped beam pattern but not necessarily StVZO and a killer stand light, which probably means using the dyno as a charger. When the bicycle new age arrives, I'm sure that will happen. https://i.pinimg.com/originals/b4/65...0a983373df.jpg

Considering the history of the autobahn and the autostrada and the Routes Nationale in France, what you're really pining for is a Fourth Reich. Mind you, Mr Trump, very unconservatively, is keen on massive infrastructure investment.

As an economist, I think he's fighting with himself: you can't have both high prior unemployment in a growing economy and massive infrastructure expenditure without inviting high wage inflation, for which business will curse you immediately, and the workingman shortly after he discovers his fatter wage packet buys nothing more.

Andre Jute
A dispassionate view
Old February 26th 18, 06:52 AM posted to rec.bicycles.tech
Andre Jute[_2_]
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Posts: 8,572
Default Inexpensive LUX meter from China to measure your bike lamp's output

When Tesla starts making bikes, you guys will have to eat your words. -- AJ

On Monday, February 26, 2018 at 4:58:12 AM UTC, Jeff Liebermann wrote:
On Sun, 25 Feb 2018 18:58:00 -0500, Frank Krygowski

On 2/25/2018 6:17 PM, Jeff Liebermann wrote:
On Sun, 25 Feb 2018 14:43:04 -0500, Frank Krygowski

(* I guess I should use kilo-lumen instead of mega-lumen. The latter
probably won't be available for a year or two.)

1.29 MegaLumens available real soon now:
Whether it actually delivers 1.29 MegaLumens is questionable.

It's very bright, but they're claiming 1.29 MegaCd, which is not the
same as 1.29 Mega lumens. (And note that the solid angle of that light's
beam is tiny.) At about 9:00 he claims 1887 lm. That's solidly in the
kilo category.

Oops, false alarm and wishful thinking on my part. Sorry.

But it's true that nothing exceeds like excess.

Bigger numbers always sell better. The problem with megalumen LED's
is that using the best of todays technology, LED's will deliver about
150 lumens/watt. In order to produce 1 Megalumen, the LED's will
1,000,000 lumens / 150 lumens/watt = 6,666 watts
The better 18650 LiIon cells can deliver perhaps 2A without adversely
affecting the battery life (in charge cycles). To deliver 6,666 watts
will requi
6,666 watts / (2A * 3.6V) watts/cell = 926 cells
I suspect that might be a little too large and heavy to be
successfully installed on a bicycle.

The lamp will also be a problem. It will probably use the current 100
watt LED technology, which produces about 6,000 lumens per LED. Notice
the drop to 60 lumens/watt for these monsters. To produce 1 Megalumen
with 100 watt LED's will requi
1,000,000 lumens / 6,000 lumens/watt/LED = 167 LED's
In terms of size, they are about 40 x 40 mm = 0.0016 sq-meters
167 of these would occupy:
167 * 0.0016 = 0.267 sq-meters
If this were a square, it would be about 0.5 meters on a side, which
is probably too large for a bicycle.

Therefore, you can sleep easily and worry free tonite and not have
nightmares of Megalumen lights appearing at your next ride.

And BTW, the pitchman is just a _little_ over the top! I think he's - um
- in love.

Everyone has their own style. At least he's not dull and boring like
many YouTube presentations[1]. Hmmm... I wonder if I should do a
YouTube video demonstrating my method of measuring lumens?

[1] This is a common problem among speakers accustomed to giving live
presentations to an auditorium audience and then switching to YouTube
videos. In order to convey enthusiasm, the speaker uses various body
gestures and facial expressions that are difficult to see in an
auditorium. So, the speaker intentionally exaggerates these gestures
and expressions so they can be seen. However, when doing a YouTube
video, or while being recorded from a TV camera, the camera is a few
feet away and every little gesture and expression can easily be seen
by the audience. If the speaker acts the same in front of the camera
as they might do in front of an auditorium audience, the gestures and
expressions look grotesque and very un-natural. I suspect this might
be the excess enthusiasm that we're seeing in the video.

Jeff Liebermann
150 Felker St #D
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558


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