8255A是可编程的,可通过软件来设置芯片的工作 方式。连接外部设备时,通常不需要附加外部电路

一、单项选择题(在每小题的四个备选答案中,选出一个正确答案,并将正确答案的序号填在题干的括号内。每小题2分,共30分) 1.由理想二极管构成的限幅电路如下图所示当输入电压Ui=9V时,输出电压Uo为多少?() A.3V B.6V C.9V D.15V

实践证明:正确地利用这种对称性质会使网络 的分析得到很大的简化。 具有翻转对称性质的网络绕位于其所在平面上的 a轴(下图中的虚线)转逆时针或顺时针)180°后, 无论在几何上和电气上都保持不变。这种网络由 两个互为镜像的子网络构成

Any periodic waveform f(t)f(t) can be expressed by a Fourier series provided that (1) If it is discontinuous, there are only a finite number of discontinuous in the period T (2)It has a finite average value over the period T (3)It has a finite number of positive and negative maximums in the period T

We consider each term of the Fourier aeries representing the voltage as a single source. The equivalent impedance of the network at no is used to compute the current at that harmonic. XL(n) =noL and XC() =-1/noC The sum of these individual responses is the total response i

In the chapter, we shall define the basic active and passive circuit models, explain power conventions and determine when power is delivered and absorbed, state Ohm's law and Kirchhoff's law, determine the equivalent resistance of a passive circuit containing only resistors

In the chapter we present resistive circuit analysis methods. The first is based on KCL and determines all the node-to-datum voltages in a given circuit and is known as node analysis. The second method, based on KVL, determines all loop current and is known as loop analysis. After discussing superposition, we will introduce Thevenin's and Norton's theorems

In this chapter we introduce a circuit element that is very important in circuit design, the operational amplifier.This element will be used extensively in the studies of future chapters. Here we consider its use with resistors only to perform the algebraic functions of multiplication, addition and subtraction

In the chapter we shall present an introduction to nonlinear circuit analysis and shall examine a few interesting examples of that are used in practice. The principle of analysis will be emphasized. Graphical solution techniques will be given first. In addition, the basic concept of the phase plane shall be considered

In the chapter, we first define mutual inductance and study the methods whereby its effects are included in the circuit equations. We conclude with a study of the important characteristics of a linear transformer and an important approximation to a good iron-core transformer which is known as an ideal transformer