LED wick, also known as LED, is made of synthetic semiconductor materials such as gallium arsenide, gallium aluminum arsenic and gallium phosphide, and its internal structure is composed of PN junction with unilateral conductivity. When DC voltage is applied to the light-emitting diode PN junction, the potential barrier of PN junction decreases, and the carrier diffusion movement is greater than the drift movement, so that holes in P region are injected into N region, and electrons in N region are injected into P region. In this way, when the injected holes and electrons meet, they will recombine and release energy in the form of luminescence, thus making the diode emit light. When manufacturing light-emitting diodes, different materials can emit different colors of light. There are four kinds of LED driving circuits for lighting, namely DC driving circuit, AC driving circuit, pulse driving circuit and color-changing luminous driving circuit. When LED is used as indicator light, a current limiting resistor should be connected in series, and the resistance value of this resistor should be selected according to the different working voltage and current required by LED. The voltage drop of LED is generally 1.5~2.0 V, and the working current is generally 10~20 mA.