LED flashlight failure report

Teehee.... I've spent 1/2 my life (so far) crawling around looking for "lost" items. Some found, some not. Was working on a 76 Chevy pickup of mine one time, rebuilding carb - disconnected the two throttle return springs (one inside the other) = *never* did find them. sigh. Ken.

I just now did as you suggest. To my eyeballs at least, changing the dutycycle from 50% to 100% had the same effect as changing the DC current from 50% to 100%. When I monitored the current with an analog meter (Simpson 260), changing the average current by a factor of 2 looked the same whether I did it by changing DC voltage or changing duty cycle.

Note that perceived brightness is proportional to the logarithm of light intensity. Weber Fechner law. See, e.g.,

Twice the luminous intensity looks "a little brighter" but nowhere near twice as bright. Steps of equal change in perceived brightness might be 6.25%, 12.5% 25%, 50% and 100% average current, whether it's varied by changing dutycycle or DC current. You see three steps of brightness change from 12.5% to 50%, only one more step from

50% to 100%

The flashing light that made the choppers crash was probably from automatic weapons....

but I did check on epilepsy, and then set the flash rate on my daughter's very bright red flashing bike lights at about 3 Hz to be safe.

Meant to say "three steps of brightness change from 6.25% to 50%".

"As physicists now know, there is some nonzero probability that any object will, through quantum effects, tunnel from the workbench in your shop to Floyds Knobs, Indiana (unless your shop is already in Indiana, in which case the object will tunnel to Trotters, North Dakota). The smaller mass of the object, the higher the probability. Therefore, disassembled parts, particularly small ones, of machines disappear much faster than assembled machines." Greg Dermer: rec.crafts.metalworking

Yep. That's exactly what happened. If any of you kind folk happen to find my LED flashlight innards, please give a holler.

Thank you.

Jim

Glad to -- if you will only post a link to an image of the innards, so we know what they look like. :-)

Good Luck, DoN.

So THAT's what went crunch when Icame down the cellar steps tonight. The little critter made it all the way to Waterloo Ontario (it was a tiny peice of PC board with a couple funny electronic parts on it - and the cat had been playing with it)

A LONG time ago (as will be seen) I dropped a small, irreplaceable part. As all fumble-fingers must do, I had trained myself to freeze and listen carefully at the first hint of dropping something: dead silence. I looked everywhere that might have muffled the sound of a small part landing and rolling away, but couldn't find it. Later, I found the part in my pant cuff. (When was the last time you wore trousers with permanent cuffs? For me it must have been late '50s or early '60s.)

Don't do that; you will never have the impetus of losing something else down the hole to cause you to find the LED.

-- --Pete "Peter W. Meek"

(When

Ha! I don't recall when that was. The first thing I did with work pants in "the good old days" was to remove the cuff. Those suckers can hold one hell of a lot of chips, not just irreplaceable parts!

H