在Multisim 10软件环境下，设计一种由运算放大器构成的精确可控矩形波信号发生器，结合系统电路原理图重点阐述了各参数指标的实现与测试方法。通过改变RC电路的电容充、放电路径和时间常数实现了占空比和频率的调节，通过多路开关投入不同数值的电容实现了频段的调节，通过电压取样和同相放大电路实现了输出电压幅值的调节并提高了电路的带负载能力，可作为频率和幅值可调的方波信号发生器。Multisim 10仿真分析及应用电路测试结果表明，电路性能指标达到了设计要求。 Abstract: Based on Multisim 10， this paper designed a kind of rectangular-wave signal generator which could be controlled exactly composed of operational amplifier， the key point was how to implement and test the parameter indicators based on the circuit diagram. The duty and the frequency were adjusted by changing the time constant and the way of charging and discharging of the capacitor， the width of frequency was adjusted by using different capacitors provided with multiple switch， the amplitude of output voltage was adjusted by sampling voltage and using in-phase amplifier circuit，the ability of driving loads was raised， the circuit can be used as squarewave signal generator whose frequency and amplitude can be adjusted. The final simulation results of Multisim 10 and the tests of applicable circuit show that the performance indicators of the circuit meets the design requirements.
上传时间： 2014-01-21
上传用户：shen007yue
QX5305 是一款高效率，稳定可靠的高亮度LED灯驱动控制IC，内置高精度比较器，off-time控制电路，恒流驱动控制电路等，特别适合大功率，多个高亮度LED灯串恒流驱动。 QX5305采用固定off-time控制工作方式，其工作频率可高达2.5MHz，可使外部电感和滤波电容、体积减少，效率提高。 在DIM脚加PWM信号，可调节LED灯的亮度。 通过调节外置的电阻，能控制高亮度LED灯的驱动电流，使LED灯亮度达到预期恒定亮度，流过高亮度LED灯的电流可从几毫安到2安培变化。 方框图： 管脚排列图： QX5305的特性 可编程驱动电流，最高可达2A 高效率：最高达95% 宽输入电压范围：2.5V~36V 高工作频率：2.5MHz 工作频率可调：500KHz~2.5MHz 驱动LED灯功能强：LED灯串可从1个到几十个LED高亮度灯 亮度可调：通过EN端PWM，调节LED灯亮度 QX5305应用范围 干电池供电LED灯串 LED灯杯 RGB大显屏高亮度LED灯 平板显示器LED背光灯 恒流充电器控制 通用恒流源。 工作原理简述： QX5305 采用峰值电流检测和固定off-time控制方式。片内的R-S触发器分别由off-time定时器置位和CS比较器、FB比较复位，它控制外部MOSFET管并和功率电感 L、LED、肖特基二极管共同构成一个自振荡的，连续电感电流模式的升压型恒流LED驱动电路（参见图1）。 除了固定off-time控制这点外，QX5305的工作方式和普通的电流模式PWM控制型DC/DC升压电路非常相似。当工作在连续电流模式下时，流过功率电感的电流IL如图所示：
上传时间： 2013-10-26
上传用户：TF2015
TheTool is highy customizable map editor(based on QT) which can be extended via LUA scripts. A first implentation is ready and can be published to the public. The editor is the perfect tool who wants to design some 3d games but don t have time to write
标签： customizable extended TheTool scripts
上传时间： 2013-12-12
上传用户：lanwei
URL编程例子，通过IP获取计算机名字。运行方法：1. Compile: javac GetHost 2. Run: java GetHost 111.111.111.1(your IP or others)
上传时间： 2015-02-13
上传用户：徐孺
a very simple program that prints "Hello World" to the serial port of the 8051. When you can successfully build and run this program, you have used the entire toolset including:
标签： the program success simple
上传时间： 2013-11-26
上传用户：stampede
dances Act now and you ll be given a free membership to a top Internet firm who is changing people s lives for the better.Mary L. White of LA. stays at home with her children and works just 3 1/2 hours a day... she now earns twice as much money as she did before. Frank Herns Jr. of NY takes 2 vacations a year to the Caribbean and enjoys more time and freedom than ever before. Jane Kennedy of FL fired her boss after 5 months. She finally has the time and money she needs to complete her college education. Craig Garcia of CA tripled his income in just 90 days because took advantage of his free membership.
标签： membership Internet changing dances
上传时间： 2015-03-08
上传用户：xhz1993
最新的支持向量机工具箱，有了它会很方便 1. Find time to write a proper list of things to do! 2. Documentation. 3. Support Vector Regression. 4. Automated model selection. REFERENCES ========== [1] V.N. Vapnik, "The Nature of Statistical Learning Theory", Springer-Verlag, New York, ISBN 0-387-94559-8, 1995. [2] J. C. Platt, "Fast training of support vector machines using sequential minimal optimization", in Advances in Kernel Methods - Support Vector Learning, (Eds) B. Scholkopf, C. Burges, and A. J. Smola, MIT Press, Cambridge, Massachusetts, chapter 12, pp 185-208, 1999. [3] T. Joachims, "Estimating the Generalization Performance of a SVM Efficiently", LS-8 Report 25, Universitat Dortmund, Fachbereich Informatik, 1999.
上传时间： 2013-12-16
上传用户：亚亚娟娟123
JAVA开发的日期控件，带星期的，可以录入又可以自动选择，内附手册及示例，支持time型。
上传时间： 2013-12-26
上传用户：朗朗乾坤
介绍几种cpuThe 8xC251SA/SB/SP/SQ improves on the MCS-51 architecture and peripheral features, introducing the advanced register based CPU architecture i.e., the MCS 251 microcontroller architecture. The register based CPU supports a 40-byte register file. In addition, the 8xC251SA/SB/SP/SQ microcontroller has 256-Kbyte expanded external code/data memory space and 64-Kbyte stack space. The new controller is also specially designed to execute C code efficiently. More importantly, the 8xC251SA/SB/SP/SQ maintains binary code compatibility with MCS 51 microcontrollers but at the same time allows the use of the powerful MCS 251 microcontroller instruction set, with many new 8, 16 and 32 bit instructions available. The 8xC251SA/SB/SP/SQ has 512 bytes or 1 Kbyte of on-chip data RAM options and is available in 16 Kbytes and 8 Kbytes of on-chip ROM/OTPROM or ROMless options.
标签： architecture introducin peripheral improves
上传时间： 2015-03-15
上传用户：ccclll
FreeRTOS，这个比 Real Time Linux 和 eCos 更小的实时操作系统，并且你也不用为这两个大的操作系统弄得头大了。FreeRTOS是一个非常小的实时操作系统，它包含有一个实时的内核及一个内核调制程序。它支持的单片机有 Philips ARM7, TI MSP430, Renesas (Hitachi) H8/S, Atmel AVR, Motorola/Freescale HCS12, Motorola/Freescale ColdFire, 及其他8051的单片机
标签： FreeRTOS
上传时间： 2014-05-28
上传用户：253189838
