Red (RGB)[edit]

Red, green and blue lights, representing the three basic additive primary colors of the RGB color system, red, green, and blue

  Color coordinatesHex triplet#FF0000sRGBB (r, g, b)(255, 0, 0)HSV (h, s, v)(0°, 100%, 100%)CIELChuv (L, C, h)(53, 179, 12°)SourceHTML/CSS[3]ISCC–NBS descriptorVivid reddish orangeB: Normalized to [0–255] (byte)

The color displayed at right, red (RGB), RGB red, or electric red[citation needed] (as opposed to pigment red, shown below) is the brightest possible red that can be reproduced on a computer monitor. This color is an approximation of an orangish red spectral color. It is one of the three primary colors of light in the RGB color model, along with green and blue. The three additive primaries in the RGB color system are the three colors of light chosen such as to provide the maximum gamut of colors that are capable of being represented on a computer or television set, at a reasonable expense of power. Portable devices such as mobile phones might have an even narrower gamut due to this purity–power tradeoff and their "red" may be less colorful and more orangish than the standard red of sRGB.

This color is also the color called red in the X11 web colors, which were originally formulated in 1987. It is also called color wheel red. It is at precisely zero (360) degrees on the HSV color wheel, also known as the RGB color wheel (Image of RGB color wheel). Its complementary color is cyan.

Red (CMYK) (pigment red)

Cyan, magenta, and yellow are the three subtractive primary colors used in printing

  Color coordinatesHex triplet#ED1B24sRGBB (r, g, b)(237, 27, 36)HSV (h, s, v)(357°, 89%, 93%)CIELChuv (L, C, h)(51, 157, 12°)SourceCMYKISCC–NBS descriptorVivid reddish orangeB: Normalized to [0–255] (byte)

Pigment red is the color red that is achieved by mixing process (printer's) magenta and process (printer's) yellow in equal proportions. This is the color red that is shown in the diagram located at the bottom of the following website offering tintbooks for CMYK printing: [1].

The purpose of the CMYK color system is to provide the maximum possible gamut of colors capable of being reproduced in printing.

Psychedelic art made people used to brighter colors of red, and pigment colors or colored pencils called "true red" are produced by mixing pigment red with a tiny amount of white. The result approximates (with much less brightness than is possible on a computer screen) the electric red shown above.

Red (Crayola)

  Color coordinatesHex triplet#ED0A3FsRGBB (r, g, b)(237, 10, 63)HSV (h, s, v)(346°, 96%, 93%)CIELChuv (L, C, h)(50, 153, 8°)SourceCrayolaISCC–NBS descriptorVivid redB: Normalized to [0–255] (byte)

The color defined as red in Crayola crayons is displayed at right.

Red was one of the original colors formulated by Crayola in 1903.

Red (Munsell)

The hues of the Munsell color system, at varying values, and maximum chroma to stay in the sRGB gamut

  Color coordinatesHex triplet#F2003CsRGBB (r, g, b)(242, 0, 60)HSV (h, s, v)(345°, 100%, 95%)CIELChuv (L, C, h)(51, 159, 8°)SourceMunsell Color WheelISCC–NBS descriptorVivid redB: Normalized to [0–255] (byte)

The color defined as red in the Munsell color system (Munsell 5R) is shown at right. The Munsell color system is a color space that specifies colors based on three color dimensions: hue, value (lightness), and chroma (color purity), spaced uniformly in three dimensions in the elongated oval at an angle shaped Munsell color solid according to the logarithmic scale which governs human perception. In order for all the colors to be spaced uniformly, it was found necessary to use a color wheel with five primary colors—red, yellow, green, blue, and purple.

The Munsell colors displayed are only approximate as they have been adjusted to fit into the sRGB gamut.

Red (NCS) (psychological primary red)

Approximations within the sRGB gamut to the primary colors of the Natural Color System, a model based on the opponent process theory of color vision

  Color coordinatesHex triplet#C40234sRGBB (r, g, b)(196, 2, 52)HSV (h, s, v)(345°, 99%, 77%)CIELChuv (L, C, h)(41, 127, 8°)SourcesRGB approximation to NCS S 1080-R[4]ISCC–NBS descriptorVivid redB: Normalized to [0–255] (byte)

The color defined as red in the NCS or Natural Color System is shown at right (NCS 1080-R). The Natural Color System is a color system based on the four unique hues or psychological primary colors red, yellow, green, and blue. The NCS is based on the opponent process theory of vision.

The Natural Color System is widely used in Scandinavia.

RGB LED Schematic

There are actually two types of RGB led’s; the common cathode one and the common anode one. In the common cathode RGB led, the cathode of all the led’s is common and we give PWM signals to the anode of led’s while in the common anode RGB led, the anode of all the led’s is common and we give PWM signals to the cathode of led’s.

The one that we are going to use is the common cathode RGB led. So, we will connect the common pin to the GND of Arduino and the other three leads of the led’s to the PWM pins of Arduino.

Note

You cannot distinguish between the common cathode and common anode type by just looking at the RGB led because both look same. You will have to make the connections to see that either it is common cathode or common anode.

The RGB led has one big lead than the other leads. In the common cathode case, it will be connected to GND and in the common anode case; it will be connected to 5V.

Arduino RGB LED Circuit Diagram

Connect the cathode of the RGB led which is the longer pin of RGB led to the GND of Arduino and the other three pins to the pin 11, 10, 9 of Arduino through the 220 ohm resistors. The resistors will prevent the excess amount of current to flow through the RGB led.

If you are using the common anode RGB led, then connect the long lead to the 5V of Arduino.

Note

If you have any other Arduino, then make sure that you are using the PWM pins of that Arduino. The PWM pins have a ~ sign with them.

Working

Inside the RGB led, there are three more led’s. So by changing the brightness of these led’s, we can obtain many other colors. To change brightness of RGB led, we can use the PWM pins of Arduino. The PWM pins will give signal different duty cycles to the RGB led to obtain different colors.

The below RGB color wheel will help you in selecting different colors for Arduino RGB led.

Overview

In LED strips world, there are (so) many models.

As explained on Wikipedia... "The most common design differences are in how individual LEDs are controlled, specifically differences in color and whether or not each LED is addressable.

Single Color, non-addressable: Every LED on the strand is a single white colour, typically ranging from 2700K to 6500K in colour temperature, or any of several monochrome colors covering the range of the visible spectrum (generally from 400-700 nanometers in wavelength).

Multicolor, non addressable: Each LED is capable of displaying red, green, blue, or all three (white), driven by three input power rails. All the LEDs display the same colour at any one time, but the colour can be manipulated by varying the voltage applied to each of the three power inputs.

RGB, addressable: Multiple colours and addresses. Each LED has its own chip meaning they can be individually triggered for chasing, strobing, and colour changing"

As a generic rule of thumb, you can consider that "cheap RGB LED strip" = "non addressable". There are numerous tutorials on addressable LED strips but not that much on simple, non addressable ones.

LED Strip

Here is how my LED strip looks like. The strip is divided into segments, each segment hosting 3 RGB LEDs:

A segment

Connections between segments

Here is how my LED strip is wired, internally:

Some models share a common POSITIVE, other shares a common NEGATIVE. My LED strip is as per the following:

Input Voltage

The next topic to consider is .... input voltage. LED strip lights most commonly operate on 12 or 24 volts DC from a power supply. Mine was 12 VDC. Depending on the strip length, you should pay attention to current as well and select a power supply that can handle LED strip current requirements.

If you just want to turn LED strip on/off (as a whole or per color), relays are okay and easy to setup but if you want to control intensity as well (dimming), then MOSFETs are a great solution.

In order to control colors (and intensity), I need to control A1, A2 and A3. The LED strip requires 12 VDC feed and, even if you had a 5 VDC LED strip, it would require to much current to be controlled directly, that's why I need some kind of circuit based on transistors.

Control Circuit

Here is how my control circuit looks like (duplicate it 3 times, one for each color):