Christmas lamp is a solid-state semiconductor device, i.e. light emitting diode, which can convert electric energy into visible light. It can directly convert electricity into light. The heart of LED is a semiconductor chip. One end of the chip is attached to a bracket, one end is the negative electrode, and the other end is connected to the positive electrode of the power supply, so that the whole chip is encapsulated by epoxy resin.
The semiconductor wafer is composed of two parts. One part is a p-type semiconductor, in which holes are dominant, and the other end is an n-type semiconductor, in which electrons are mainly. When these two semiconductors are connected, a p-n junction is formed between them. When the current is applied to the wafer through the wire, the electrons will be pushed to the P-region, where the electrons and holes recombine, and then the energy will be emitted in the form of photons. This is the principle of LED light emission. The wavelength of light, that is, the color of light, is determined by the material forming the p-n junction.
The single LED lamp beads produced by the Christmas lamp factory can only work under low voltage (about 3V) and low current (about several milliamps), and the light emitted is very weak. Many led beads need to be connected in series or in parallel; At the same time, a single LED lamp bead is unidirectional conductive. In order to make full use of the positive and negative half cycle current of AC power, an integrated circuit chip is required to convert the AC 220V power supply into DC power whose voltage and current can match the LED assembly, so as to meet the requirements of the LED lamp bead assembly and enable it to emit light normally.
Power connection method of Christmas lamp manufacturers: the general voltage of LED Christmas lamp is DC 12V, so switching power supply is required. The size of power supply is determined according to the power and connection length of LED Christmas lamp. If you don't want each LED Christmas lamp to be controlled by one power supply, you can buy a high-power switching power supply as the main power supply, and then connect all the input power supplies of LED Christmas lamps in parallel (if the wire size is not enough, it can be extended separately) to be uniformly powered by the main switching power supply. The advantage of this is that it can be controlled centrally. The inconvenience is that the lighting effect and switch control of a single LED Christmas lamp cannot be realized. The specific method can be measured by yourself.