Light-emitting diodes are referred to as LEDs, and light-emitting diodes are made of different materials, so they can emit light of different colors. Its colors are red light, emerald green light, yellow light, yellow-green light, orange light, purple light, infrared light, ultraviolet light, and white light. The shapes of light-emitting diodes are: circle, rectangle, triangle, square, combination shape, special shape, etc. There are four commonly used LED application circuits, namely DC drive circuit, AC drive circuit, pulse drive circuit, and color-changing light-emitting drive circuit.