A colour changing LED isn't one LED in a package but three LEDs along with a small computer to drive them. The LED is made up of red, green and blue LEDs each of which can be controlled by a microcontroller. Since the two legs on the LED that supply the power are connected to the microcontroller and not the LED elements a current limit resistor is not required.
The microcontroller is able to turn each of the colours on or off, so if the red LED is turned on then the output from the colour changing LED is red. When the blue LED is turned on it is blue, if both the blue and red LEDs are turned on then the colour changing LED is a shade of purple (called magenta). Similarly combining red with green gives yellow and blue & green gives cyan.
Although the colour changing LED uses the six colours mentioned above, it slowly changes from one to another. This is still done using the three basic red, green & blue elements. If the red LED is combined with the blue LED, but the blue LED is only driven at 50% of its normal brightness then a colour half way between red and magenta is generated.
Whilst the red LED is left turned on, if the blue LED is slowly taken from 0% brightness to 100% brightness then the colour will gradually change from red to magenta.
If a standard LED is turned on and off very quickly, say 100 times every second then as far as the human eye is concerned it looks like it is constantly on. If the amount of time the LED is on for is the same as the time it is off for then it will be on for 50% of the time and 50% of its full brightness.
This same method can be done with the three LED elements inside the colour changing LED. This means it is possible to combine any amount of the red, green and blue to give the desired colour. Looking once again at the change from red to magenta, if the blue LED starts mainly turned off, goes to being on and off in even amounts and then to mainly being on then the the colour will change as required.

### Which Resistor Should I Use with my LED?

LED brightness is controlled using a current limit resistor to drop some of the battery voltage, calculate the resistance using the formulas in this guide. A worked example shows the calculation used to work out the resistance to accompany an LED in a typical circuit using a 9V battery.

Shantanu Godbole

Hey being an electronics engineer this was good addition to my knowledge.I learnt a lot of things from this blog.If you want more information about jobs related with electronics engineering do visit our website job vacancy result

Abdullah Khan

I control some light with the help of rgb small led which changes colour when it connect to battery and the car or bike is off its works fine and changes colour on sequence when I start a car it's stops changing and all the colour on led gets on and never get change when car is on start so what should I do please reply if anyone knows

Mark Donnison

Hi Gab, we are unfamiliar with your mouse and as such we can only advise you to contact the manufacturer or possibly the seller. Sorry that we couldn't be more help.

gab

Guys, please help me my mouse is Programmable , a gaming mouse but my problem is that my mouse only stay in one color instead of 4 colors the seller said I turn on the macro programming setting but I don't have any idea what i did i just entered the mouse to my Computer , even though I use the driver of the mouse but that's how it goes it didn't change

Mark Donnison

Hi Ella, the legs will obviously have to be completely protected from water/moisture to avoid short circuits, so having the whole LED behind some sort of protection from the elements would be beneficial.

Ella

Are these waterproof? And can I use them outside?

Mark Donnison

Hi Carson, we sell parts that could be used to create one but not a kit or product for this.

carson leach

do you sell christmas tree color changing controllers?

Mark Donnison

Hi Christina, without running some tests it is difficult to say.

Michael Shreeve

externally controlled rgb led's have been available for some time now. Commercially they are in a string and come with a controller on the line and a remote control to comunicate with the controller.

Christina

Hi, can anyone tell me why the red has started flickering and shuts off on my multicoloured shower head? It’s been fine for over a year.

Ben

I believe they are asking, can they be reprogrammed?

Sue

Does anyone else get annoyed by colour changing LEDs? – I want choose the colour/s – not cycle through a load of colours that clash with my decor until I get to the perfect colour for a fleeting moment! All the affordable decorative LED items cycle and very few facilitate colour selection. There's a huge market for you – right there!

Mark Donnison

Hi Guy, we would need some more information in order to make a useful suggestion. We would need to know if it is the LED itself that is responsible for the timing of the cycle or if it controlled by the circuit that the LED is a part of.

Darrell

That is such a good explanation. Nice easy steps that build on the previous ones very concisely and makes it a joy to learn.

Guy Manganese

I have an existing color changing led which cycles in 7 seconds. I need the full cycle to be closer to 1 to 2 minutes long. Any suggestions?

Mark Donnison

Hi Paul, We sell two different types which you can find at www.kitronik.co.uk/3527 or www.kitronik.co.uk/3544. If you look at the product page for www.kitronik.co.uk/3544, you will see the operating voltage and current requirements and that this LED does not require a current limit resistor if it is being powered in line with the values shown.

Paul hickling

What power supply would I need and apart from an on off switch would I need anything else

Mark Donnison

You're welcome John! Best of luck with your rediscovery of electronics.

John Potter

Having studied the inside of these LED's one can only be astonished at the complexity and work involved in their manufacture. To me it seems to be almost the crowning glory of modern electronics, such a lovely thing at such a low price. I have returned to electronics as a hobby after a 50 year break and what I have found is beyond my imagination. Thank you so much for this explanation.

Mark Donnison

Hi, The colour changing lights are preprogrammed to cycle through the colours in a set way.

Gulmina

Can we turn these changable colour lights into one single colour????

Mark Donnison

Hi Andres, There are colour changing LED's and there are RGB LED's, the colour changing LED's are pre-programmed to cycle through the colours in a pre determined way and this is controlled by a small on-board computer. With RGB LED's you can control which colour is active using PWM (Pulse width modulation). If you Google PWM you should get plenty of information that will help you.

Andres

Is The LED Micro controllers phisical like any other controller or is it IN the LED. I would like to know for a DIY Mouse Project, But The LEDs in the mouse has changes colors automaticaly and i don't know how to change it or keep it on the same color Please Answer, Thank you.

Rob Haywood

Hi Shonda, The LED contains a micro controller which controls the LED. We sell two different types which you can find at www.kitronik.co.uk/3527 or www.kitronik.co.uk/3544.

shonda blackmon

what is the price ? I need product information on how it works and how is it controlled