361–370 of 519 posts
So, engineering lead of a (outdoor) led Luminaire manufacturer here. And our sales director used to work for one of the biggest Asian light bulb OEMs. Happy to answer specific technical questions out there that this article triggered.
Earlier quoted context omitted.
Those early Home Depot Cree bulbs were definitely defective. We bought a ton of them and have since replaced nearly all under warranty... twice. The first round they replaced with identical ones, which also quickly failed. (Always the same; started with an intermittent flicker, which progressively got more severe and regular.) More recently we've gotten a new design back, which seem better. Fortunately, after the fir…
"Fortunately, after the first ones, it's been as simple as replying to the email thread and telling them how many more replacements I need!" Could you tell us that email address ? I have a box of 14 original Cree bulbs that I would like to get replaced...
So, engineering lead of a (outdoor) led Luminaire manufacturer here. And our sales director used to work for one of the biggest Asian light bulb OEMs. Happy to answer specific technical questions out there that this article triggered.
Do all types emit RF noise? What to look out for to avoid it?
The cheaper bulb in the original article has linear current control. Inside the ASIC, this could be as simple as a BJT or FET in saturation with a (somewhat) controlled base/gate voltage, maybe with some temperature compensation.
The linearly regulated bulb will have less RF emissions, though you could theoretically still have a bit of rf trash from edge effects depending on the rectifier and filter cap.
Any bulb that has passed FCC Class B will have an upper bound on conducted and radiated emissions, but you can pass such tests on a wide range of margins, and therefore certification isn't useful to clarify which bulbs have the lowest emissions.
So, engineering lead of a (outdoor) led Luminaire manufacturer here. And our sales director used to work for one of the biggest Asian light bulb OEMs. Happy to answer specific technical questions out there that this article triggered.
What do you recommend to buy if I want a ~2700 lumen, high CRI (>90), and non flickering bulbs for home?
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…
Shaking a hand with fingers spread out somehow works to spot flicker. If the light source flickers, you see oddly sharp finger positions in the air. It's not the most sensitive or easy to interpret method.
So, engineering lead of a (outdoor) led Luminaire manufacturer here. And our sales director used to work for one of the biggest Asian light bulb OEMs. Happy to answer specific technical questions out there that this article triggered.
If cost were less of a concern, what engineering changes would you make to the bulb?
1) Better cooling: non-tooth paste thermal compound, more space for heatsinks
2) Not overdriven LEDs
3) Introduce DC power lines (within the house/building) - galvanic corrosion still might be an issue
4) In lack of point 3 - more efficient AC -> DC converters, preferably with lower temp threshold,
having 150C default for the internal mosfet on 8pin LED driver is really high.
4a) AC-DCs require quality passive components: coil and caps.Earlier quoted context omitted.
Why do so many of the bulbs run hot? Like so hot you can't hold them in your hand if they were on when you unscrewed them. Isn't this a lot of wasted energy?
All bulbs produce heat, both from the LEDs and the electronics. Incandescent bulbs were blazing hot, too, and they radiated IR on top everything else. A high efficiency LED assembly is still producing on the order of 50% light and 50% heat.
Earlier quoted context omitted.
They're basically at the same level if you don't use high end CPUs and gaming GPUs. Also see here: http://www.extremetech.com/extreme/135719-5-9-watts-the-worl... - tldr: 30w idle for an unmodified average system. Mind you this was 2012, mid range systems surely haven't gotten more power hungry since then.
> Also see here: http://www.extremetech.com/extreme/135719-5-9-watts-the-worl... . - tldr: 30w idle for an unmodified average system. That's an order of magnitude more than an idle laptop. And they're not talking about any sort of "average system" they're ballparking a "reference desktop" which tops out at 150W under load , that's not just "don't use a gaming GPU" that's "don't use a GPU at all". And if you're buildi…
Uuh.. yes... And an order of magnitude less than "several 100w light bulbs"
> And if you're building a "desktop computer" with an APU and an SSD… why are you building a desktop computer?
Ergonomics?
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…
Shaking a hand with fingers spread out somehow works to spot flicker. If the light source flickers, you see oddly sharp finger positions in the air. It's not the most sensitive or easy to interpret method.