The characteristics of LED light -emitting diode are: very low working voltage (some only a few volts); small working current (some can be emitted in only a few pm); good impact resistance and seismic resistance, high reliability, long life span ; The power and weakness of the passing through the modulation can easily adjust the strength of glowing. Due to these characteristics, LED light -emitting diode is used as a light source in some optoelectronic control devices and is used as a signal display in many electronic devices. The working voltage of the red and yellow LED light -emitting diode is 2V. The working voltage of other colors is 3V. The working current of the general LED light -emitting diode is 20mA. If it is connected to the power of the five V, the power supply voltage is reduced. The voltage is the voltage that is divided by the voltage resistance, and then use this voltage to remove the current of the light -emitting diode to calculate the resistance of this resistor. For example, the 3V light-emitting diode (5-3) /0.02=100 Euros, 2V light emitting diode (5-2) /0.02=150 Euros, but not all LED luminous diode working currents are 20mA, some are a bit bigger There are also a little small. In actual use, you can also use the whole flow -emitting diode to separate the pressure. The voltage drop of a light -emitting diode is 0.7V. Use four series to connect with 2.2V to less than 20mA, red light 1.2V, and green light 1.4V (when it is turned on). Positive working current IF: It refers to the positive current value of the LED light -emitting diode when the normal light emitting. Generally, the working current of LED luminous diode is more than a dozen mAs to tens of mA, while the working current of low -current LED is below 2mA (the brightness is the same as that of ordinary luminous pipes). Positive working voltage VF: Generally, the working voltage given in the LED light -emitting diode parameter is obtained under a given forward current. Generally measured when if = 20mA. LED light -emitting diode is positive working voltage VF is 1.4 to 3V. When the temperature rises in the outside world, VF will decrease. The brightness and current are not linear. When the current is large, the brightness does not change much. As long as the current exceeds the maximum forward current, it will be burned. The special mainly depends on the information, and the general current is selected at 3-20mA. To control the positive current of the LED light -emitting diode, we must know that an important parameter of the LED light -emitting diode: VF value. There are different VF values of LED light -emitting diodes of different colors, and the VF values of LED light -emitting diode of the same color are also different. Most applications need to be splitted and split. The maximum forward current of different types of LED light -emitting diodes is different. The maximum positive current of the LED luminous diode with a diameter of 5mm in diameter is generally 25mA, and the actual application is often working at 20mA. In order to ensure that the LED light -emitting diode can be reliable and stable, many occasions are required to use constant current technology to drive the LED light -emitting diodes. LED light -emitting diodes are referred to as LED. The diode made of compounds made of (GA) and arsenic (AS), and phosphorus (P) can radiate visible light when the electron and the cave are compounded, so it can be used to make LED light -emitting diode, which is used in circuits and instruments as a circuit and instrument. The indicator light, or a text or number display. The diode of the phosphate has red light, the phosphate diode is green, and the silicon carbide diode is yellow