Light emitting diode bulbs have essential differences from traditional incandescent bulbs in both structure and light emission principle. A diode is a commonly used component in electronic circuits, which is made of a semiconductor PN junction, electrode leads, and a casing. A diode has two electrodes with a PN junction, so it is called a diode. A diode has unidirectional conductivity. There are many types of diodes, including detectors, rectifiers, voltage regulators, switching diodes, damping diodes, light-emitting diodes, phototubes, etc.
Light emitting diodes are usually made of semiconductor materials such as gallium arsenide and gallium phosphide. They emit light when subjected to forward current, and the color of the light depends on the material used. They 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 based on the voltage of the pins.
