Selfbuilt's introductory flashlight video primers

selfbuilt

Flashaholic
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You are the best, and the reason why I am broke...
Yes, I realize my reviews may make certain lights look "glamorous", and contribute to that desire to acquire them. :shrug:

But I always like it when people post in my threads that I saved them money, by describing features or a build/interface that does not meet their needs. I know the exerience of being disappointed with a light I've just brought, discovering some quirk of the interface or build ergonomics that aren't suited for my use.

In any case, I hope these videos continue to provide useful background info for people. I know how overwhelming this place can seem to newcomers!

:wave:
 

selfbuilt

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Out of curiosity, is there anything missing from these primers that people would like to see me cover in future ones?
 

Swede74

Enlightened
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Sep 30, 2011
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Out of curiosity, is there anything missing from these primers that people would like to see me cover in future ones?

I think an overview of batteries would be much appreciated. Perhaps it seems like a huge undertaking as there is quite a lot to cover: chemistry, capacity, charging, safety et cetera, but if you have the time and energy (pun intended) I for one would, as always, be grateful for your hard work.
 

selfbuilt

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I think an overview of batteries would be much appreciated. Perhaps it seems like a huge undertaking as there is quite a lot to cover: chemistry, capacity, charging, safety et cetera, but if you have the time and energy (pun intended) I for one would, as always, be grateful for your hard work.
That's a good idea. It is a lot to cover, but I would likely focus on rechargeables (NiMH and Li-ion), and the basic charger options. Good opportunity to explain why users of Li-ions should invest in a DMM ... :whistle:

I will definitely add that to the top of my list for new primers - thanks. :)
 

selfbuilt

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Sorry Gordo, did that get quote cut-off? :thinking:

Something else I am thinking about is discussing varibility in measurement, precision vs accuracy, and the importance of visually inspecing the data. Some of that is covered in my ANSI FL-1 primer and Runtime Graph primer, but I thought it might be useful to go into a little more detail about how it typically all works out in practice.
 

LGT

Enlightened
CPF Supporter
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Great work by selfbuilt. Primer four really explained something I've read about, but didn't really understand until now. This thread has got sticky written all over it. The truth is out there.
 

WindsurfMaui

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Aug 21, 2014
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7
Great primer videos. Would you consider doing a video on the relationship of volts and amps to lux? Not the complicated formulas but a simple guideline on how battery volts effect brightness. Why are my LED's brighter when powered by 2 16340 3.7v (charged to 4.2) rather than 1 18650 3.7v (charged to 4.2v) when the 18650 holds more than twice the capacity of the 16340?
 

selfbuilt

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Great primer videos. Would you consider doing a video on the relationship of volts and amps to lux? Not the complicated formulas but a simple guideline on how battery volts effect brightness. Why are my LED's brighter when powered by 2 16340 3.7v (charged to 4.2) rather than 1 18650 3.7v (charged to 4.2v) when the 18650 holds more than twice the capacity of the 16340?
It's a good point - although one the experts in the battery and electronics subforum here could answer better than I. Simply put, higher voltages make it easier for circuits to drive the output higher (and two cells in series have twice the voltage of single cells). But I'd have to let the experts there really get into the details. :wave:
 

magellan

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Feb 3, 2014
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As as far as the human visual system goes, the flicker fusion rate is only about 60 Hz which is why some people are bothered by fluorescent lights. But PWM in flashlights shouldn't be a problem since we can't detect it because it's higher frequency. There should be no brightness issues either because of the way the retina processes brightness information.

On the dog hearing issue, an interesting question. I don't have complete information on that but although they could certainly hear it I don't think the DB level would be enough to cause any damage though I suppose it could be annoying. But remember dogs live in a world of many more smells and sounds than we do anyway. Their sense of smell is 10,000 to 100,000 times ours. But I would think a flashlight driver wouldn't do much because of the low power level unless someone here has more specific info.

Thank you for the interesting and informative videos, which I also found entertaining - though the latter may not have been their intended purpose :). They also sparked a couple of questions, or perhaps even concerns:

1. Do you think it is possible that a light that uses pulse width modulation on lower levels may be harmful to a person's eyes if used for extended periods of time, for instance when reading on a bus? I didn't know until I watched your video that PWM means the emitter is always driven at 100%; my concern is that the pupil may not have time to contract during the very short bursts of light, like it would if you used a light that puts out hundreds of lumens (constantly) as a reading light. To put it in another way, is it possible that when using PWM, the eye is exposed to more light than a person is aware of, that it can somehow override, or "outperform" the body's reflexes?

2. My ears are in their late 30's, and although not as perceptive as they once were, they can still detect inductor whine on my Xtar WK21 if I hold it close to them. Dogs, and many other animals have much better hearing, and my second question is: It is obvious that dogs can detect inductor whine, and at frequencies that no human can hear, but is it possible that it is very annoying for them to listen to, or even painful? Most dogs would probably find a way to convey it to their owner if that were the case, but then again, it is possible that not all of them would. Perhaps the sound polluted-world we live in makes it a moot question, at least for dogs that live in the city, but if there is cause for concern I will consider using a single-mode light rather than one with PWM for dog walks in the future.
 
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