The light-emitting diode light bulb is fundamentally different from the traditional incandescent light both in terms of structure and light-emitting principle. Diodes are commonly used components in electronic circuits. They are made of semiconductor PN junctions, plus electrode leads and shells. Diode has PN junction two electrodes, so called diode. The diode has unidirectional conductivity. There are many types of diodes, such as detector tubes, rectifier tubes, voltage regulator tubes, switch tubes, damper diodes, light emitting diodes, and photocells.
Light-emitting diodes are usually made of semiconductor materials such as gallium arsenide and gallium phosphide, and emit light when passing through a forward current. The color of the light emitted depends on the materials used and can emit red, yellow, green, and infrared light. Light-emitting diodes are generally packaged in a transparent plastic, with a long positive electrode and a short negative electrode. Some light-emitting diodes have three lead-out pins that emit two colors of light depending on the voltage of the pins.