Tri Color LED

A Tri Color LED is an LED that can light up into two different colors depending on where current flows to on the LED. A typical LED can only light up to one color. For example, a red LED can emit only a red light. A green LED can emit only a green light. However, with a tri color LED, two different colors can be lit with the same LED.

Tri color LEDs come in either 2 or 3 pins or terminals.

Below is the schematic for a 2 terminal tri color LED:

2 Terminal Tri Color LED

In the 2 terminal type, the LEDs are connected anode to cathode. Which LED lights depends on which terminal is made positive. If positive voltage is supplied to the green anode, the LED lights green. If positive voltage is supplied to the red anode, the LED lights red.

The other type is the 3 terminal tri color LED. Below is a schematic for it:

3 Terminal Tri Color LED

In the 3 terminal tri color LEDs, the LEDs have a common ground or cathode. A positive voltage applied to either of the other two wires is used to light the corresponding LED. In order to light the green LED, current from the circuit (a few milliamperes) must be made to flow into the green anode. In this setup, the circuit will light green light. In order to light the red LED, current from the circuit (a few milliamperes) must be made to flow into the red anode. While lighting one anode, the other anode should be kept open, meaning no current should go into it.

A tri color LED is useful as an indicator. It can indicate the mode in which an electronic device is operating. For example, on a digital camera, a tri color LED may glow red when it is in recording mode and green when it is in play mode.