Photomultipliers (PMT), avalanche photodiodes (APD),ultrasonic transducers, capacitance microphones, radiationdetectors and similar devices require high voltage,low current bias. Additionally, the high voltage must bepristinely free of noise; well under a millivolt is a commonrequirement with a few hundred microvolts sometimesnecessary. Normally, switching regulator confi gurationscannot achieve this performance level without employingspecial techniques. One aid to achieving low noise is thatload currents rarely exceed 5mA. This freedom permitsoutput fi ltering methods that are usually impractical
In an increasing trend, telecommunications, networking,audio and instrumentation require low noise power supplies.In particular, there is interest in low noise, lowdropout linear regulators (LDO). These components powernoise-sensitive circuitry, circuitry that contains noisesensitiveelements or both. Additionally, to conserve power,particularly in battery driven apparatus such as cellulartelephones, the regulators must operate with low input-tooutputvoltages.1 Devices presently becoming availablemeet these requirements (see separate section, “A Familyof 20mVRMS Noise, Low Dropout Regulators”).
Features: High efficiency, high reliability, low cost AC input range selected by switch 100% full load burn-in test Protections: Short circuit / Over load Fixed switching frequency at 25KHz Cooling by free air convection 1 year warranty Dimensions: 199*98*38mm (L*W*H)
The P89LPC912/913/914 are single-chip microcontrollers in low-cost 14-pin packages, based on a high performance processor architecture that executes instructions in two to four clocks, six times the rate of standard 80C51 devices. Many system level functions have been incorporated into the P89LPC912/913/914 in order to reduce component count, board space, and system cost.
在理論分析循環(huán)碼編碼和譯碼基本原理的基礎(chǔ)上，提出了基于單片機(jī)系統(tǒng)的(24，16)循環(huán)碼軟件實(shí)現(xiàn)編碼、譯碼的方案。仿真結(jié)果表明(24，16)循環(huán)碼能有效地克服來(lái)自通訊信道的干擾，保證數(shù)據(jù)通信的可靠及系統(tǒng)的穩(wěn)定，使誤碼率大幅度降低。本論文對(duì)(24，16)循環(huán)碼的研究結(jié)果表明，可以有效地降低錯(cuò)誤概率和提高系統(tǒng)的吞吐量，實(shí)現(xiàn)糾錯(cuò)僅需要在接收端增加有限的存儲(chǔ)空間和計(jì)算復(fù)雜度，具有一定的實(shí)用價(jià)值。
Abstract:
Based on analyzing the theory of encoding and decoding of cyclic code， this paper showed the schemes of encoding and decoding of(24，16)cyclic code by the software and based on microcontroller. Simulation results show that using (24，16) cyclic codes can effectively overcome the interference from communication channel， ensure the reliability and stability of data communication systems， and reduce the bit error rate greatly. The results of this paper show that by using the (24，16) cyclic code， the error rate can be reduced and the system throughput can be improved. Meanwhile， the system only needs to enlarge limited storage space and computation the complexity at the receiving end to realize error correction. Thus the (24，16) cyclic code has a practical value.
便攜式信號(hào)采集在機(jī)器健康診斷系統(tǒng)中有較高的應(yīng)用價(jià)值。機(jī)器健康診斷的信號(hào)特點(diǎn)是包括低頻信號(hào)。本文研究是為了實(shí)現(xiàn)簡(jiǎn)易而且低成本的低頻便攜式信號(hào)采集。以Microchip公司單片機(jī)PIC18F1320為核心設(shè)計(jì)信號(hào)采集電路，實(shí)現(xiàn)了信號(hào)的采集和保存。系統(tǒng)采用串行電可擦除芯片24LC32A保存數(shù)據(jù)，經(jīng)過(guò)有線通信，信號(hào)數(shù)據(jù)由串行口通過(guò)MAX232芯片輸送到微型計(jì)算機(jī)接收和保存，最后繪制出信號(hào)波形。 微型計(jì)算機(jī)程序采用Visual Basic編程。研究成功采樣頻率為3 kHz的復(fù)雜信號(hào)，證明該方案符合設(shè)計(jì)要求。
Abstract:
Portable signal acquisition is useful in machine health monitoring systems. The signal characteristics of machine health monitoring includes low frequency signals. The goal of this study is to realize simple, inexpensive and portable low frequency signal sampling. This paper provides the project of signal acquisition system design based on PIC18F1320 microcontroller manufactured by the Microchip Technology Incorporation to achieve signal sampling and storage. The system adopted EEPROM 24LC32A to store the signal data. The microcomputer received data via wired link with the MAX232 IC through the serial port. The microcomputer program, programmed in Visual Basic, received the data, stored it and plotted the signal. The study successfully samples 3kHz complicated signals and thus meets the design requirement.
針對(duì)目前使用的RS232接口數(shù)字化B超鍵盤(pán)存在PC主機(jī)啟動(dòng)時(shí)不能設(shè)置BIOS，提出一種PS2鍵盤(pán)的設(shè)計(jì)方法。基于W78E052D單片機(jī)，采用8通道串行A/D轉(zhuǎn)換器設(shè)計(jì)了8個(gè)TGC電位器信息采集電路，電位器位置信息以鍵盤(pán)掃描碼序列形式發(fā)送，正交編碼器信號(hào)通過(guò)XC9536XL轉(zhuǎn)換為單片機(jī)可接收的中斷信號(hào)，軟件接收到中斷信息后等效處理成按鍵。結(jié)果表明，在滿(mǎn)足開(kāi)機(jī)可設(shè)置BIOS同時(shí)，又可實(shí)現(xiàn)超聲特有功能，不需要專(zhuān)門(mén)設(shè)計(jì)驅(qū)動(dòng)程序，接口簡(jiǎn)單，成本低。
Abstract: Aiming at the problem of the digital ultrasonic diagnostic imaging system keyboard with RS232 interface currently used couldn?蒺t set the BIOS when the PC boot， this paper proposed a design method of PS2 keyboards. Based on W78E052D microcontroller，designed eight TGC potentiometers information acquisition circuit with 8-channel serial A/D converter， potentiometer position information sent out with keyboard scan code sequentially.The control circuit based on XC9536 CPLD is used for converting the mechanical actions of the encoders into the signals that can be identified by the MCU， software received interrupt information and equivalently treatmented as key. The results show that the BIOS can be set to meet the boot， ultrasound specific functionality can be achieved at the same time， it does not require specially designed driver，the interface is simple and low cost.
為了有效地提升鉛酸蓄電池的使用壽命，同時(shí)實(shí)現(xiàn)對(duì)充電過(guò)程的監(jiān)控，設(shè)計(jì)出一種用單片機(jī)控制的36 V鉛酸蓄電池充電電源。本電路采用反激式拓?fù)洌B續(xù)電流工作模式，電源管理IC設(shè)計(jì)在電源的副邊，由ELAN公司的EM78P258N單片機(jī)模擬，是用可編程器件模擬電源管理IC，實(shí)現(xiàn)智能電源低成本化的一次成功嘗試，通過(guò)對(duì)單片機(jī)的軟件設(shè)計(jì)實(shí)現(xiàn)了充電電源的狀態(tài)顯示、充電時(shí)間控制、報(bào)警、過(guò)溫保護(hù)、過(guò)壓保護(hù)、過(guò)流保護(hù)等功能。本充電器真正的實(shí)現(xiàn)了鉛酸蓄電池的三段式充電過(guò)程，其最高輸出功率可達(dá)90 W，效率約85%，成本不到20元，具有很高的市場(chǎng)競(jìng)爭(zhēng)力。
Abstract: In order to extend the life of lead-acid battery efficiently and supervise the charging process meanwhile， a 36V lead-acid battery charge powe supply controlled by microcontroller is designed. The charger is flyback switching power supply and works in CCM mode. A EM78P258N microcontroller made by ELAN microelectronics corporation is used as power management IC which is designed at the secondary circuit. The project is a successful attempt to low-cost intelligent power used microcontroller simulating power management IC. The charger also has the functions of the status reveal， charge time control， alarming， thermal protect， current limit and overvoltage protect by the software design. The circuit actually implements the three-step charge process， whose power is up to 90W and whose efficiency can get 85%. The net cost of this charger is less than 20 RMB， so that the charger is of powerful market competitiveness.
生活中許多目標(biāo)的高度和水平距離需要進(jìn)行測(cè)量。目前主要的測(cè)量方法，仍以傳統(tǒng)的皮尺丈量為主，測(cè)量效率不高，有時(shí)還很不方便，沒(méi)有技術(shù)成熟的數(shù)字式測(cè)高測(cè)距產(chǎn)品。以基本的數(shù)學(xué)方法為理論依據(jù)，利用遙控小車(chē)做為載體，采用角度傳感器測(cè)量角度、霍爾傳感器測(cè)量水平距離等，通過(guò)單片機(jī)LM3S615進(jìn)行數(shù)據(jù)計(jì)算，實(shí)現(xiàn)了對(duì)待測(cè)目標(biāo)物體的高度、水平距離等數(shù)據(jù)的快速、精確和數(shù)字式的測(cè)量，高度測(cè)量精度可達(dá)99.06%，水平測(cè)量精度則可達(dá)98.06%。
Abstract: In our lives， the height and horizontal distance of some goals are needed to be measured. Because the currently used methods are still traditional tape-based measuring methods， and the measuring efficiency is low and inconvenient so some kinds of digital and portable measuring methods or instruments are needed. Based on the basic math theory， this paper designed and manufactured a portable， digital and remote controlled measuring mobile small vehicle， which assembled with angle measuring sensor for angle measurement and Hall sensor for horizontal distance measuring. MCU LM3S615 calculated the height and horizontal distance data gotten from these sensors. The measuring process is simple， the measuring results are more accurate and the measuring efficiency is higher than traditional measure instruments. The accuracy of height and distance measurement can reach 99.06% and 98.06%.
針對(duì)目前汽車(chē)追尾事件頻發(fā)問(wèn)題，提出一種防汽車(chē)車(chē)前和車(chē)后追尾的安全裝置設(shè)計(jì)。該設(shè)計(jì)以高性能、低功耗的8位AVR微處理器ATmega8L為核心，結(jié)合霍爾式車(chē)速傳感器、激光雷達(dá)測(cè)距裝置和MMA7260QT加速度傳感器，能夠兼顧車(chē)前和車(chē)后，摒棄以往設(shè)計(jì)中只考慮車(chē)前或車(chē)后單一性缺點(diǎn)，尤其適用于高速、夜晚或新手行車(chē)。
Abstract:
Aiming at the high frequency of vehicle rear-end collision，a safe device design of anti-vehicle rear-end collision is presented.In the design，the high-performance，low-power8-bit AVR microprocessor ATmega8L is utilized as a core combined with Hall-type speed sensor，laser-radar ranging devices and the acceleration sensor MMA7260QT.The design considers both the front and back of a car，and overcomes the drawbacks of former designs in which only the front or the back of the car is considered，so it is especially suitable for high-speed，night or the beginner’s driving.
