Questions tagged [lighting]

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How to build and power very large scale addressable LEDs?

A 2 part question. I've built large scale LED projects in the past, but for the next one it would be massive (a black hole disc with a diameter of 54 ft), and addressable LEDs on the top and bottom. ...
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Best unit of measurement to compare brightness of different wavelengths of light

I'm designing a light source that emits several wavelengths of physical light (via LEDs). The light emitted will be measured with a CMOS sensor (from a mirrorless camera), and in order to properly ...
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Is it possible to estimate location of a source of light using single camera?

I wonder if it is possible to estimate location of a static source of the light using single camera? If possible how does it work in a nutshell? If not possible any work around like using multiple ...
1 vote
2 answers
98 views

Sun exposure in room as a function of day and time?

Background (may be safely ignored): I am buying (most of) a rowhouse from the 1930s. I am now working with an architect to improve its energy efficiency. Let us focus on the main room, which can be ...
1 vote
1 answer
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Flood light pole components

I saw this flood light pole. It has two LED bulbs, but I do not know what the box in the middle is (it was not an LED), could you guys help me understand what this could be? This flood light is ...
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Can I use a PWM motor regulator to control a LED string?

I recently bought some LED Christmas lights, but they are too bright. So I was thinking that maybe I could regulate the output by using a PWM regulator? My LED lights have an output of 30V from the ...
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1 vote
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How to calculate the 'Daylight Factor' of a room?

I am a faculty in a public school. Our school has to submit an infrastructure report to the funding agency. One of the questions asked is to calculate the 'Daylight Factor' in each classroom. I have ...
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Determining an adequate lens for collimation

I'm looking to develop an optical system to collimate a LED that is going to be fitted to glasses. I have a 5 mm diameter de-domed LED with a circular aperture that I need to produce a clean and even ...
1 vote
1 answer
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Which optical filter to use for flat black non-glare aerospace indicator?

I am currently designing a LED light indicator for use in an aircraft cockpit replica. I’m asking for expert advice on the type of lenses to use in order to get a result similar to shown pictures. ...
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1 answer
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Lightning strike and metal structures in garden

I am worried about metal posts (support structures for plants) placed in garden and danger from lighting strikes. Posts are 3 meter long rebars and they are about 1,5 m driven into ground. Around ...
2 votes
1 answer
79 views

Where to acquire / create LED optics

I'm working on a few projects that require lenses to focus LED light flashes, similar to those lenses used by police lights (TIR lens) and other strobe traffic lighting utilizing Fresnel lenses. I've ...
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4 votes
1 answer
488 views

Alternatives to laser line?

I'm trying to project a very thin line at a low angle over some surface defects (peaks and troughs). The scale is ~20mm square, but the defects can be sub-mm (0.2 - 1.0mm). I am currently using a line ...
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2 votes
3 answers
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How can I achieve good diffusion from an LED light source?

I have a light fixture which is designed as three rows of LED light strips. The problem is that the LEDs appear as brilliant points of light. In the fixture I want to diffuse this light so that it ...
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1 answer
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What has changed since the 1990s that made "LED lights" possible?

I keep seeing all kinds of objects now having small but very bright LED lights in them, seemingly never burning out, requiring almost no batteries/power, and extremely durable. I remember being a ...
1 vote
1 answer
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Passive Infrared Sensors (PIR) spectrum and reflections

I have a common PIR occupancy sensor (Lutron MS-OPS5M-WH). I am trying to get the sensor to cover an irregular-shaped room. I could expand the field-of-view of the sensor to cover the whole room by ...
1 vote
2 answers
113 views

Why aren't driving roads also illuminated from the ground up, like airport runway lights?

Compared to its Mar 2016 article, the Nov 29 2018 article by the Insurance Institute for Highway Safety proclaims that "headlights improve, but base models leave drivers in the dark" and ...
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-1 votes
1 answer
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Why HMMWV's lights aren't located at the edges?

Hummvee has front lights located far from edges, closer to each other. That makes it harder to see edges of the vehicle in the dark.
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1 vote
1 answer
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Relations/Equations to do with light diffusing materials

I recently started as designer at a making custom signage (small signs viewed up close, so there are lots of sizing limitations) and none of the other designers have any solid rules to rely on for ...
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2 answers
156 views

Activating lights using a motion sensor?

I was wondering how I would configure some sort of setup to get lights like this turn on a timer once activated by a motion sensor. I want them to turn on for about 15 seconds and then turn off once ...
7 votes
3 answers
175 views

LED Lumen Calculations

I am using an LED as a point source for a school project. I have two questions in regards to the LED(s). I know that light follows the inverse square law when measuring perceived brightness, but all ...
1 vote
0 answers
63 views

Rube Goldberg, twisting in a lightbulb

For my rube golberg project I have to twist a lightbulb in and have it turn on. I have seen different videos on how they do it but they never explain it and most of the videos are blurry. We can't ...
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3 votes
1 answer
89 views

Street Light Arrangement Method

Hello I am a high school student and I am curious about how street light is arranged along the road. Is there government laws to install street light on the road or is the arangement of the street ...
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2 answers
556 views

how to implement autofocus for video projector

I have a modified pico video projector that I need to add an autofocus to. The focusing ring already has a fast stepper motor added to it. If the focus had to be done on the middle of the projection ...
4 votes
2 answers
218 views

What plastic material blocks the most amount of light?

If I have a grid array of LED's surrounded by roughly 0.7mm thickness plastic walls. What material at this thickness would prevent light bleed side to side so that individual LED's can light up but ...
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3 votes
4 answers
2k views

How do I measure the brightness of a light bulb?

I am working on a science fair project. My question is if electricity moves better through a thin wire or a thicker wire. I need to collect data and make charts, and the thing I want to measure is the ...
2 votes
2 answers
866 views

How to predict shadows of a house (3D modeling + sunlight)?

Imagine a house/building, seen from outside, at sunrise. As the the sun moves in the horizon, a) the shadow of the house is displaced/deformed, and b) some faces of the house have more/less sunlight ...
2 votes
2 answers
3k views

LED color change in extreme cold

Which part of the LED is affected when it is exposed to liquid nitrogen? I have seen experiments showing LED's brightness increasing and color shifting, when the LED is submerged in liquid nitrogen. I ...
0 votes
1 answer
131 views

LED controller to control individual RGB diodes remotely?

I'm working on a project which utilizes an iPad to change colors of individual lights in array of ~200 RGB LEDs. I have little knowledge of large-scale LED configurations and could use some direction. ...
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1 vote
3 answers
692 views

Does temperature affect the colour of the light emitted by an LED?

Suppose you have an LED that emits a spectrum of colours such that the resultant colour emitted is white. Will changing the temperature if the LED itself change the composition of the light's colour ...
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3 answers
102 views

Is there a way to determine the colour information of light emitted from an LED?

Say you have an LED light that emits green light. Are there sensors out there that could accurately determine the colour information of the green light? Such as the relative values of red, blue and ...
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1 vote
2 answers
485 views

Diffuse uniform LED back lighting

Good morning/afternoon/evening, I am working on a project in my spare time, and was wondering how this effect is created. and I am going to assume this is more than just a cutout with an LED behind ...
-1 votes
2 answers
274 views

What is the significance of curvature in the arm of a streetlight?

I have been trying to find out the significance of the usual streetlight design - Why is there curvature of the arm holding the bulb of the light? I have been unable to any reason as to why it may be. ...
1 vote
2 answers
126 views

Light bulbs with highest energy efficiency [closed]

Most specs for light bulbs list luminous efficiency (or, more accurately sometimes, luminous efficacy) but not energy efficiency. Luminous efficacy tells you how bright the light is as observed by a ...
0 votes
1 answer
42 views

Thickness of a 3d print general purpose plastic/PLA 230 V ~ isolator?

I'd like to design a minimal thin light switch which holds an illuminant with standardized socket, e.g. E14, E27, and has itself such a socket to be screwed in a support and a switch which will be ...
2 votes
3 answers
292 views

Animated light box signs

In the old days there was a type of sign/light you would find in bars and restaurants which was animated. It would be a lit scene usually of water, like a lake with a waterfall, and by some means it ...
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