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What Happened to the 100000 Hour LED Bulbs?

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Re: What Happened to the 100000 Hour LED Bulbs?

#421

Post by Dylan16807 »

m463 wrote: post #394
handzbagz wrote: post #383

Earlier quoted context omitted.

Just how likely is this to happen though, it would have to be the only light source and be flickering with exactly the same frequency as the machinery is traveling at (which i assume for most devices varies a lot). Not saying it can't happen but it does seem stupidly hard to achieve.

I would imagine there's a higher-than-average chance of this because most AC motors are definitely syncronized with the 60hz (or 50hz) AC source. There's a chance the lights might also derive from this.

> There's a chance the lights might also derive from this.

If the light is flickering it's absolutely guaranteed that it's derived from this.

But it's hard to imagine a lightbulb that emits a short enough pulse of light to make something look stopped. Even an absolute garbage one-way rectifier will be emitting light more than a quarter of the time. That can make a tool look odd, but it won't make it look still.

Re: What Happened to the 100000 Hour LED Bulbs?

#422

Post by nwallin »

handzbagz wrote: post #383
TheSpiceIsLife wrote: post #378

Earlier quoted context omitted.

LED flicker could prove harmful or fatal if you work with anything that rotates or reciprocates. The rotating / reciprocating mass may appear stationary at some RPM. Just a reminder to only ever use incandescent or halogen lights around machinery you can touch while in operation: drills, lathes, mills, slotting machines, etc.

Just how likely is this to happen though, it would have to be the only light source and be flickering with exactly the same frequency as the machinery is traveling at (which i assume for most devices varies a lot). Not saying it can't happen but it does seem stupidly hard to achieve.

It's not true that it has to be the only light source. All of the light sources have to be the same type and on the same circuit, which is fairly common.

Many AC motors are synchronized to the frequency of the power line, by the same principal that turbines in the power grid are. So 60hz AC often means 30hz = 1800 rpm motor, and 59.8hz AC means 29.9hz motor. So if you have LEDs with a half bridge rectifier and your machinery is 180 degree rotationally symmetric, it will appear to not be moving, even if the line frequency fluctuates.

Re: What Happened to the 100000 Hour LED Bulbs?

#423

Post by NeedMoreTea »

handzbagz wrote: post #383
TheSpiceIsLife wrote: post #378

Earlier quoted context omitted.

LED flicker could prove harmful or fatal if you work with anything that rotates or reciprocates. The rotating / reciprocating mass may appear stationary at some RPM. Just a reminder to only ever use incandescent or halogen lights around machinery you can touch while in operation: drills, lathes, mills, slotting machines, etc.

Just how likely is this to happen though, it would have to be the only light source and be flickering with exactly the same frequency as the machinery is traveling at (which i assume for most devices varies a lot). Not saying it can't happen but it does seem stupidly hard to achieve.

Pretty common, about as common as the wagon wheel effect in 24fps film movies. In just the same way, the item can appear to stop, run slow, or run backwards, just as with film. No it does not have to be the only light source, just the nearest one to the machinery.

Fluorescent tubes are most noticeable, LEDs a little less. Tungsten or Halogen are the only sensible option for workpiece illumination.

Re: What Happened to the 100000 Hour LED Bulbs?

#425

Post by userbinator »

I have some electronics with LED displays/indicators that have been on 24/7 for over 30 years, or 256k hours, and haven't failed. The difference between those and the ones in bulb replacements is that the latter are driven much harder, to the point that they dissipate a lot of heat. Indicator/display LEDs don't get hot or even noticeably above ambient.

Thus it seems that, just like with incandescent bulbs, LEDs will last practically forever if they're run dimly. The difference is that LEDs are actually more efficient at lower current densities, where they're converting more of their input power to light instead of heat, but cost considerations has lead to typical bulbs driving them at much higher currents for more brightness but correspondingly less life and efficiency. They're still far more efficient than incandescents, so I guess that's what counts...

Re: What Happened to the 100000 Hour LED Bulbs?

#426

Post by TheSpiceIsLife »

dsfyu404ed wrote: post #405
roenxi wrote: post #403

Earlier quoted context omitted.

Nobody? That is a high bar. Mechanics tend to be pretty cluey, but for the effort of getting proper lighting why nobody should be taking that sort of risk. Sight is one of those fundamental lets-feed-in-useful-information sensors for keeping situations safe.

Most people spec'ing out machine shops are not experts in lighting other than more = better. This is a really, really low risk we're talking about. Like basically the stars have to align for someone to get hurt.

I started to write a lengthy rebuttal, but decided to go with something more concise.

Never underestimate the ability of machinery to rapidly render you dead.

Never underestimate the ability of otherwise intelligent people to intentionally disable safeguards, or guninely make mistakes.

Re: What Happened to the 100000 Hour LED Bulbs?

#428

Post by yeutterg »

arm wrote: post #385
pistachiopro wrote: post #316

Earlier quoted context omitted.

I completely agree, flicker has been the most distracting part of switching to LEDs, for me. Here are two good sites that posted graphs of light intensity over time for a bunch of different bulbs: http://www.ledbenchmark.com/ http://sle.se/michael/led/ (Swedish) Unfortunately, they both stopped updating around 2015. Anyone know of similar sources for more recent bulbs?

In the huge HN thread here¹, yeutterg mentioned² their Bedtime Bulb: > “ I am on a mission to make lighting healthy. That's why I made Bedtime Bulb: https://bedtimebulb.com/ It has the lowest flicker I've ever seen in a bulb form factor—even less than those claiming to be "flicker-free." ” In addition to that, a few other database sites that test for flicker were mentioned here³. ―――――― ¹ — https://news.ycombinator.c…

I've tested a bunch of bulbs for flicker with a handheld flicker meter and with a photodiode connected to an oscilloscope. It's funny that some of the bulbs out there claiming to be "healthy" have terrible flicker. One product from Soraa was flickering at over 50%, almost as bad as the cheapest/worst LED bulbs you can buy.

I don't have a database, but I can say that most (but not all) filament designs are terrible for flicker--ours is an exception. Philips products seem to have gotten worse in quality over time, probably to remain competitive, but they are better than the worst. Ikea's stuff is pretty good overall. I don't have a consistent recommendation for low-flicker general lighting right now, as every brand has good and bad products.

Re: What Happened to the 100000 Hour LED Bulbs?

#429

Post by bradyd »

timbit42 wrote: post #420
MPSimmons wrote: post #395

Earlier quoted context omitted.

I can spot a Cadillac or GMC vehicle on the road a mile behind it from the flicker of the taillights. It's terrible.

Why do they flicker? Are they AC powered?

You can dim LEDs by turning them on and off really fast using a process known as pulse width modulation (PWM). Ideally for something like brake lights you would use a constant current driver to control the light level to prevent flickering. I don't know why GM is using PWM, but I'm guessing they just use a cheap control circuit. I really hate their LED tail lights. Just moving your eyes from side to side is enough to easily see the flashing.

Re: What Happened to the 100000 Hour LED Bulbs?

#430

Post by yeutterg »

MPSimmons wrote: post #395
mrb wrote: post #235

Lifetime isn't even my #1 concern with LED bulbs. It's strobing/flickering. I film all the LED bulbs I buy in slow motion at 240 fps with an Android phone, and play the movie back on a PC with mplayer using the dot(".") key to move frame by frame. Here is a shot I made comparing 2 brands of LED bulbs: https://youtu.be/QbenId_F2RQ (Edit: yeah you don't have to transfer to a PC, just playing back in slow motion on the…

I can spot a Cadillac or GMC vehicle on the road a mile behind it from the flicker of the taillights. It's terrible.

Agreed. Most car manufacturers' LEDs flicker (just look at any slow-motion video, such as those on Top Gear or The Grand Tour), but GM's are at a much lower frequency that is visible if the vehicle is in motion, or you are in motion.
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