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What kind of current does a light emitting diode need?
Like conventional PN junction diodes, light emitting diodes are current-dependent devices with its forward voltage drop VF, depending on the semiconductor compound (its light colour) and on the forward biased LED current. Most common LED’s require a forward operating voltage of between approximately 1.2…
How is the colour of the light emitted by an led determined?
Therefore the colour of the light emitted by an LED is NOT determined by the colouring of the LED’s plastic body although these are slightly coloured to both enhance the light output and to indicate its colour when its not being illuminated by an electrical supply.
Why are LEDs called tricolour light emitting diode?
The most popular type of tricolour light emitting diode comprises of a single Red and a Green LED combined in one package with their cathode terminals connected together producing a three terminal device. They are called tricolour LEDs because they can give out a single red or a green colour by turning “ON” only one LED at a time.
How does a forward biased diode produce monochromatic light?
When the diode is forward biased, electrons from the semiconductors conduction band recombine with holes from the valence band releasing sufficient energy to produce photons which emit a monochromatic (single colour) of light.
What is the characteristic curve of a Zener diode?
Unlike a conventional diode where the intended use is to prevent current in the reverse direction, a zener diode is mostly used in the reverse region above the breakdown voltage. Its I vs, V characteristic curve is similar to ordinary diode.
How to measure current and voltage of PN junction diode?
The current vs. voltage characteristics of the PN junction diode can be measured using the Discovery Board and the following connections shown in figure 4. The green boxes indicate where to connect the Discovery board. Set up the breadboard with waveform generator output, W1, attached to one end of the resistor.