Light-emitting diode bulbs are fundamentally different from traditional incandescent lamps in terms of structure and light-emitting principles. Diode is a common component in electronic circuit, it is made of semiconductor PN junction, plus electrode lead and tube case. A diode has two electrodes with a PN junction, so it is called a diode. The diode has unidirectional conductivity. There are many types of diodes, the common ones are detector tubes, rectifier tubes, voltage regulator tubes, switch tubes, damping diodes, light emitting tubes, photoelectric tubes, etc.
Light-emitting diodes are usually made of semiconductor materials such as gallium arsenide and gallium phosphide. They emit light when passing a forward current. The color of the light depends on the material used, and can emit red, yellow, green, and infrared light. Light-emitting diodes are generally packaged in transparent plastic, with the long pin being the positive electrode and the short pin being the negative electrode. Some light-emitting diodes have three lead pins, which can emit two colors of light according to the pin voltage.
