How do you measure infrared light emitting diodes?

Last Update Time: 2018-10-26 16:48:19

How do you measure infrared light emitting diodes?

When detecting infrared light emitting diodes,there is a big difference between the pointer type multimeter and the digital multimeter.The pointer type multimeter is placed in RX1k2 the resistance value ( forward resistance ) of the black stylus connected to the positive pole and the red pen to the negative pole should be 20 ~ 40k02 ( ordinary LEDs above 200 k2 ),the resistance value ( reflection resistance ) of the black pen and the negative electrode and the red pen to the positive pole should be above 500 k2 ( close to the ordinary LEDs ).The bigger the reflective resistance is,the better. The bigger the reflection resistance is,the smaller the leakage current is,the better the quality of the pipe is. If the reflection resistance is only tens of thousands of euros,such a pipe is not available.If both the positive and negative resistance values are infinite or zero, it means that the inside of the measured infrared light emitting diode is broken or has been damaged.When measuring with the digital multimeter,the gear position is placed in the diode block,and the pressure drop value when the black pen is connected to the negative pole and the red pen is connected to the positive pole is 0.96 ~ 1.56V,the smaller the forward voltage,the better,that is,the starting voltage of the pipe is low. After adjusting the stylus,the number shown on the screen should be an overflow symbol " OL"or" 1 ".

what is a photosensitive diode?

Photosensitive diode is one of the most commonly used photosensitive devices.Compared with ordinary semiconductor diodes,it is similar that the tube core is a one-to-one PN junction with unidirectional conductivity,and the difference is that the light diode shell has a "window" that can shoot human light on the shape of the diode.When the light is irradiated through the window to the light diode tube,the reverse leakage current of PN junction is increased,and the leakage current is called the photocurrent;the reverse leakage current of PN junction is very small when no light is irradiated,and the leakage current is called the dark current.The shape,circuit and structure of the photodiode are shown in Figure.Figure 5-21a shows the appearance of several common photosensitive diodes;figure 5-21b is a circuit symbol of a photosensitive diode,whose character symbol (code symbol) is expressed in VDP;figure 5-21c is a photodiode structure diagram,light is focused on the tube core by an organic glass lens ("window"), causing a change in the resistance of the PN junction of the tube and receiving the corresponding change.On the circuit,there will be a photocurrent.The main parameters of the photosensitive diode are as follows.

maximum working voltage Vmax maximum working voltage is the value of the reverse voltage allowed on the photosensitive one pole in the case of no light irradiation and the reverse current does not exceed the specified value (an Yin of 0.1 mu).It is usually within the range of 10~50V.

dark current ID dark current refers to the reverse leakage current when the light sensitive one is added to the normal working voltage in the absence of light,and the smaller the better,the better the value is,the general <0. 5 A.

the photocurrent IL photocurrent means that the current of the photosensitive diode is about dozens of AMPS when a fixed light beam is irradiated with a normal reverse voltage.