Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [lighting]

178 questions
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Why did LEDs take so long to appear as light bulbs?

LEDs are an old technology, why did the industries take so long to put them into light bulbs? Was there any technological gap missing?
PDuarte
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Why does this LED bulb have an energy efficiency rating of 'F'?

In my home, I have some halogen spot lights, which have an energy efficiency rating of 'C': I would like to replace them with more efficient LED bulbs, but looking on the Philips website, they claim their bulbs are rated 'F'! LEDspot VLE GU5.3 MR16…
Rocketmagnet
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Where is the LED in this light bulb?

This light bulb is classified by its manufacturer in Europe as a Classic A 7W 230V 2700K 806lm B22d bulb. To me this bulb has the appearance of an incandescent light bulb with thin filaments of yellow/orange conducting material which give off the…
Excel r 8
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What is the theoretical limit of lumen/watt for lighting systems?

Nowadays we see LEDs with 300 lumen per watt luminous efficacy. They still waste a lot of power as heat. Now what is the limit of electricity to light conversion? Say we build an LED with 100% efficiency, which doesn't waste any power as heat or…
tigerkoley
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Why do LED headlamp bulbs need active cooling?

I decided to install LED headlamp bulbs in my car in the hope that I can avoid replacing bulbs every year. I was quite surprised to find that I can't fit replacement bulbs in my car due to the bulbs having a huge heatsink and, indeed, a fan to keep…
Lefty
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Powering and dimming a few hundred light bulbs

I want to power a very large light fixture: it has 273 G4 socket light bulbs. The bulbs I found for the thing are 12 V 5 W ones, incandescent. So the question is how to power the beast (as it is 1365 W of power), and how can I dim the whole…
A. Daty
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Are LEDs in modern streetlights usually pulsed? If so, roughly what frequency?

I can think of some reasons why modern LED streetlights would likely be pulsed; Efficient voltage conversion starting from line voltage would likely include an AC or switching step higher than 60 Hz. Highest efficiency operation of LEDs often…
uhoh
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Philips 9 W luminaire quotes 7 A for 300 ms inrush!

In his answer to Will repeatedly turning a light bulb on and off damage it? @Bradicul stated, An example of inrush current is an LED downlight fitting with 9 W (0.0375 A at 240 V) will have any average inrush current of 7 A for 300 ms. Figure…
Transistor
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Is the output of a 12V DC driver different depending on forward or reverse phase AC input?

Does the output of a 120 volt AC to 12 volt DC LED driver differ depending on whether it receives forward-phase AC input or reverse-phase AC input from a dimmer? I’m curious because I have some LED lamps that are failing prematurely and some that…
Edward Ocampo-Gooding
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Size of glass on incandescent bulb

I was buying light bulbs for a load bank for work and it occurred to me...what determines the size of the glass that goes around the filament? It seems somewhat arbitrary since it's a vacuum so it doesn't seem like heat conduction would be a factor,…
DKNguyen
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Precision mini winch (with position feedback) for kinetic lighting?

I am trying to create a kinetic lighting installation for my home, above the dining table (see example here https://www.youtube.com/watch?v=-DZ18DNbjTQ ). Obviously I will use max around 20 lights. The solutions I have found either cost above 100K…
Evans C
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How Is Intensity of Blue Light Measured?

As a hobby project and to help solve issues getting up early in the morning (specially given that it's winter and the sun isn't up until long after I am) I'm trying to find a bright blue light that I can put on a dimmer. I've read that the eye (even…
azoundria
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How much power is required to run LEDs?

I'm living off the grid in the bush in a hut I've built since this whole virus drama. My only issue is I'm not really good with electrical stuff. By this I mean I have a few basic solar set ups that I'm trying my best to get working. One gives me…
rawtribe
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Do dead CFL or LED light bulbs consume power and is it safe to leave them mounted?

Do burned-out CFL or LED light bulbs consume power when the switch is on? Is it safer to keep them in their sockets, removed or slightly unscrewed so the bottom center contact isn't touching? I replaced some dead CFLs with brighter LEDs with…
USER249
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Edge-lit LED panel best materials?

I'm trying to replicate the effect of this LED panel I found at Home Depot with a different set of LEDs and use a differently sized panel. It's basically just a diffused light that mimics a window or skylight. It's 2x2ft and produces 4250 lumens…
halph
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