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Water quality testing process , based on the measured parameters , selection of a different color reaction , the different reactants color have different spectral absorption characteristics . Characteristic absorption at the wavelength , it absorbs light energy depending on the content of the component under test . The subject based on the above characteristics , design a water quality measurement system based on LED array . The measurement system selects a particular LED -chip microcomputer as the core as a monochromatic light source , the instrument , and combined with the peripheral circuit of the A / D conversion , etc. , to achieve the conversion of the signals , processing, control of the operation , and instrumentation , display and printing functions . Instrument has a simple optical path , low power consumption , small size , easy to carry and so on . This paper analyzes based Lambert - than Beer's law the principle of water quality testing instruments , highlights the portable water analysis instruments based on the LED array . According to the linear relationship between concentration and absorbance , the design of a water quality measuring instrument . ① Based on the emission light components of the LED array , and the transmitted light receiving unit ; ② accomplished by the phototransistor in the concentration measuring system , designed photoelectric signal conversion to complete the multi-signal selector ADG608 and the completion of the A / D conversion by the AD7896 ; ( 3 ) single-chip hardware and software systems , the single-chip system , including keyboard control , printing , and liquid crystal display , responsible for calculating and processing of the data obtained after the completion of the A / D converter , and the standard curve can be corrected according to the user needs , the measurement results by the LCD , printer printout ; ( 4 ) experimental standard concentrations, linear regression method to fit the experimental data , the standard working curve keyboard operation is written to the measurement system . Portable LED array - based water quality testing instruments for water quality testing provides a simple structure , real-time detection of new measurement methods .
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