L E D Works

[shermaine]

How does a bi-color or tri-color led works?
How does they turn on different color? And what's the purpose of leds at different angle?

 

[fingaz]

Bi-colour led's usually have 3 leads to operate the two colours (they have 2 seperate led's in the same epoxy package.

Tri-colour led's have 4 leads, to operate the 3 seperate led 'dies'.
There are now 2 and 3 colour led's which change colours. These have an in-built chip which operates the 2 or 3 led's.

Try looking here for more info on led's

http://ledmuseum.org/

 

[Hero999]

A bi-colour LED has two different colour wired LEDs back to back in the same case, when the current flows in one direction, it's red and when it flows in the other direction it's green.

Tri-colour LEDs have two different LEDs in the same package, except their cathodes of anodes are alled wired to one pin and there are two other pins for each LED's annode or kathode. You can get three different colours by turning the LEDs on and off to mix different colours.

The angle, is the viewing angle.

 

[shermaine]

Does applying different voltage cause different color to light up? How does the b-color leds in handphone works? Does they amke use of the leads connection or voltage changing?

 

[fingaz]

All Bi-colour and tri colour led's are controlled by applying power to either different pins or changing the polarity. Sometimes you can change the colour emited by an led slightly if you 'over power' it, but this will permanently damage the led.

The viewing angle of multi colur led's should not alter with the different colours, but the focal point of the light will be slightly different for each colour since it is actually 2 or 3 seperate led's in the same package and they can't all sit in the same place on the reflector.

 

[fingers]

Its not the amount of voltage which makes different colours illuminate, but where the voltage is applied (which pins on the LED are connected to the circuit.)
If by tri-colour you mean red/ green/ orange there will be 2 dies (orange is both green & red on together).
Tri-colour is also red/ green/ blue where there are 3 dies. The cathode of all 3 are connected and each colour is turned on by applying 0v to the cathode and positive voltage to the anode of each colour as required.

 

[Hero999]

A tricolour LED
**broken link removed**

A bicolour LED
**broken link removed**

 

[audioguru]

If a red-green LED is called TRI-COLOUR, then a red, green and blue LED should be called MEGA-COLOUR.

 

[Krumlink]

ive heard the rgb leds called the holy crown lol

 

[Hero999]

It's all marketing hype anyway.

 

[things]

don't tri colour led's change colour automatically, or are you talking about the ones with many pins?

 

[Gayan Soyza]

In my country the price of a bicolour LED is much more than AUTOMATICALLY colour changing LED’s. I don’t know why is that.

 

[Gayan Soyza]

And recently I found an LED in the market a 5mm size. It has two pins.
The operation is when you touch the LED only its starts to LIGHT up.After couple of seconds its automatically turns OFF.Again touch then it lights up.Its funny

 

[Hero999]

That seems a bit pointless, what could you do with it? I suppose you could use it as a pushbutton switch but it depends how long it says on for after you've taken your finger off.