KEYWORDS: Data conversion, Transformers, Organic light emitting diodes, Data processing, Analog electronics, Signal processing, Error analysis, Digital electronics, Scientific research, Resistance
With the development of computer technology, all kinds of instrument operation have higher and higher requirements for data processing, and all kinds of intelligent measuring instruments have come into being. As one of the typical representatives of intelligent measuring instruments, digital voltmeter has only a history of more than 50 years since its inception, but there have been electronic tube type, transistor type, various scale integrated circuit type, intelligent type and so on. With the progress of technology, the production cost of digital voltmeter is getting lower and lower, the stability is improving, and the range is also expanding. Various advantages brought by the development of science and technology make digital voltmeter favored by all walks of life. The measurement parameters of digital voltmeter can only measure a single parameter, but now it can measure a variety of parameters, such as DC voltage, AC voltage, impedance, power and so on. This paper plans to design a three channel AC / DC digital voltmeter with simple structure and convenient operation. It can realize the automatic measurement of three channel AC and DC basic parameters. After many considerations, it is determined to design this digital voltmeter based on single chip microcomputer.
In order to solve the problem of DC capacitor voltage fluctuation during the operation of five level cascaded H bridge, a new DC capacitor voltage balance control method is proposed based on the analysis of the current control method. The superposition of active current to reference current of each phase can control the balance of three-phase voltage, and the superposition of the voltage whose phase is same as the active current but sign is contrary to the modulation wave of two H bridge unit respectively. Then the capacitor voltage on the DC side is almost maintained near the given value. The simulation results verify the effectiveness of the proposed method.
KEYWORDS: Transistors, Temperature metrology, Speech recognition, Temperature sensors, Signal detection, Power supplies, Molybdenum, LCDs, Electromagnetism, Control systems
With the development of the times, people are increasingly pursuing the comfort and convenience of life. Water is an indispensable part of people's family life. At this stage, the faucets used in most families adjust the water temperature through manual and mechanical rotation. On the one hand, the adjustment speed is slow. On the other hand, it is often difficult to accurately achieve people's really comfortable water temperature. The water outlet is either hot or cold(Tan 2013). The temperature control faucet designed in this paper is different from traditional products. It takes the STM32 single chip microcomputer as the control core, uses the high-precision temperature sensor DS18B20 to detect the ambient temperature, sends the digital temperature signal output by the AD conversion module to STM32 for processing. It displays the current ambient temperature value and each gear temperature value preset with the key on the LCD display screen. In addition, using the existing voice signal module, we can convert the voice signal into the input signal of single chip microcomputer, and then use PWM to change the speed of stepping motor, so as to control the water flow and temperature more conveniently and quickly.
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