A photoresistor concentration meter is used to detect the light energy passing through a substance to understand the composition or properties of the substance. The milliampere meter is divided into concentration groups according to relevant standards, so that the concentration value can be easily read out. First, the light transmission intensity of the standard solution must be measured, so that the concentration of the solution to be tested is known. When the VL is not lit and the photoresistors RG1 and RG2 are not illuminated by the light source, the potentiometer RP is adjusted so that the milliampere meter indicates 0, and the zero calibration is completed. At this time, the power source of the light-emitting diode VI is turned on, and the standard solution and the solution to be tested are irradiated by the light source, and the concentration of the solution to be tested can be indicated on the milliampere meter. Photosensitive resistor concentration measuring instrument circuit: Brake Disc For KIA Kia Brake Disc,Kia Auto Brake Disc,Kia Car Brake Disc,Kia Automobile Brake Disc Zhoushan Shenying Filter Manufacture Co., Ltd. , https://www.renkenfilter.com