How can LED lightbulbs change color now?


I see all the time new lightbulbs that can change color on command.
How is this done technologically ?

In: Engineering

There are multiple LEDs inside. Red, green, and blue so through different levels of brightness for each, they can make many different colors

LED bulbs already consists of multiple individual light emiting elements in order to produce enough light. If you look at an LED bulb at low power you might be able to count them. It is not unusual to have over a hundred elements in a bulb for high power lamps. For color changing lights what they are doing is adding an extra set of LED elements with a different color. They also have a way to dim each color independently.

To be able to pick any hue you want you need three elements, red, green and blue. A combination of this can make the light appear any hue or saturation you want. However the light from an RGB lamp can be a bit odd as it is emiting light in only a few specific frequencies. So for more daily use the most common lamps only have two elements, warm and cold white. These both emit a broad spectrum of light creating white light but more towards one or the other side of the spectrum. By changing the ratio of light between these you get light at different color temperatures or white balance.