Related Article: Working of Light Emitting Diode (LED)
One commonly used schematic symbol for these LEDs is shown below.
Working of Multicolor LEDs
Multicolor LEDs actually contain two pn junctions that are connected in reverse-parallel i.e. they are in parallel with anode of one being connected to the cathode of the other.
If positive potential is applied to the to terminal as shown below, the pn junction on the left will light.
If the polarity of the voltage source is reversed as shown in figure below, the pn junction on the right will light.
How Colors are Formed?
Multicolour LEDs are typically red when biased in one direction and green when biased in the other.
If a multicolour LED is switched fast enough between two polarities, the LED will produce a third colour.
A red/green LED will produce a yellow light when rapidly switched back and forth between biasing polarities.
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