Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [colour]

33 questions
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What do the colors of resistor bodies mean?

I don't mean the colored bands, but the colors of the bodies themselves. They come in brown, blue, green, etc. Is there a standard? For instance, epanorama says: But there are two resistor body colors which you should know what they need if youre…
endolith
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How can I use 5 LEDs for additive colour mixing using the CIE 1931 Chromaticity diagram?

I am using Amber, Green, Blue, White (2500K - Colour Temperature) and White (6500K - Colour Temperature) LEDs, and altering their brightness to get to a specific colour and brightness (luminous flux) on the CIE 1931 Chromaticity diagram. I am…
regamblr
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LED changing colour over time

Can a LED change colour over time? I've had a blue LED set up for some time and it use to be a much brighter (ultramarine blue) now it's heading to a more greenish dull colour. How is this happening?
mad_z
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Specific color sensing, is it possible in an economical way, without using camera/image recognition?

While I understand that color sensing with camera and sufficiently powered processor running image histogram logic (or other such algorithms) can determine presence of certain colours fairly reliably. However, are there other, significantly more…
bdutta74
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What impact, if any, does the solder mask color have on the electrical and mechanical properties of a PCB

At my place of work, we use soldermask colors as a sort of poke-yoke for manufacturing purposes E.g. Technicians know that green pcb goes with green, blue pcb with blue, etc. This has lead to some ... esoteric color choices including matte white,…
crasic
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Can a computer monitor output light invisible to the human eye?

From what I understand a computer monitor can output lots (couldn't think of a better word) of colours. Is it possible for a computer monitor (television etc) to output light invisible to the human eye?
Alex KeySmith
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How to compare brightness of different color LEDs (not RGB)?

I wonder - let's assume one would build some user interface using green, yellow and red or just any other available colored LED (not RGB LED) - what would be the proper (aka best) way to compare the brightness of LEDs in order to choose "equally…
t0bias
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How can PAL (TV) encode 3 colors in 1 phase?

As I understand it luminance is the amplitude of the signal, and color is the phase. You need 2 color signals (the third one can be derived from the other 2, like B = 1 - R - G). How can 1 phase signal encode 2 colors?
Federico Russo
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Using multiple white LEDs to obtain a unique CCT

I need to swipe between two white shades from one to another color temperature, let's say from 2700K to 6000K. Can it be done by simply mixing the intensities of two LEDs of respectively 2700 and 6000K? So that half of 2700 and half of 6000 will…
thexeno
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Colour correcting RGB LEDs - possibly with science

I have some RGB LEDs (eBay - no datasheet, 4 pin, common cathode, 5mm). I am colourblind. I'd like to create a palette of colours which appear distinctly for most people's eyes, perhaps 16 colours or more. How could I generate this palette? I guess…
Toby Jaffey
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how to measure RBG values of a color using phototransistor

I am developing a circuit which can measure RGB values of a given color. I have used LED to transmit light and reflected light is filtered by 3 R, G, B filter papers. Earlier I used LDR and found that the accuracy of the result was low even though I…
Buddhishan Manamperi
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Single transistor instead of RGB screen

In today's screens, each individual pixel is created by the combination of three transistor as Red Green Blue. But, colours are already just different frequency waves. Why aren't pixels made by just one single component to create different colour…
tcak
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Detect the colour of an LED (Red Blue or Green)

I am trying to find a way of determining the colour of an LED without an electrical connection to it, i.e a sensor pointed at the LED. I can place the sensor quite close to the RGB LED I intend to measure, but i'm struggling to come up with…
Gurn64
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how to get the RGB value of a color using phototransistor or photodiode?

I'm making a color analyzer which can measure Red, Green, and Blue portions of a color (ex: 128,255,0).I'm not supposed to use pre-made color sensors and need 1% ACCURACY. I used three LEDs - R,B & B to sequentially measure the values. When green…
Buddhishan Manamperi
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Do purple LEDs mix blue and red, or do they emit true violet?

Do the rare "violet" LEDs emit true violet (400-420nm) light, or do they mix blue and red (440nm and 700nm) light?
Bruce Wayne
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