机电专业英语

1Thyristors should not be confused with bipolar junction transistors or field-effect transistors.不应将晶闸管与双结型晶体管（bipolar junction transistors，BJTs）或场效应管（field-effect transistors，FETs）混淆起来.2BJTs and FETs are both capable of performing switching operations. As a rule, these devices are not as efficient as thyristor and do not have the power-handling capability.BJTs与FETs都能够完成开关操作。

按照惯例，这些器件并没有晶闸管那么有效率且不具备功率（电力）处理能力。

3Thyristors are used as power control devices, whereas transistors are primarily used in amplifying applications.晶闸管通常用作电力控制器件，而晶体管主要用于信号放大。

4A variety of unidirectional thyristors is now being used in industrial electronic applications. One of the first to be developed was the silicon-controlled rectifier(SCR). The term thyristor was derived form the words thyratron-transistor.工业电子应用系统目前使用了很多种单向晶闸管。

可控硅整流器（silicon-controlled rectifier, SCR）就是最初开发出的三极管之一。

术语晶闸管“thyristor”源自于单词“thyratron-transistor”。

5An SCR is classified as a reverse blocking triode thyristor. This means that the device has conductibility in only one direction. When its anode and cathode are reverse biased, the device will not conduct.SCR被归类为反向阻断晶闸管。

这意味着该器件仅在一个方向上导通。

当其阳极、负极处于反偏时，它不导通。

6The silicon-controlled switch(SCS) and the programmable unijunction transistor(PUT) are two other thyristors of this classification.可控硅开关(silicon-controlled switch, SCS)和可编程单结晶体管(programmable unijunction transistor, PUT)是该类的另外两种晶闸管。

7The internal construction of an op-amp is quite complex and usually contains a large number of discrete components.运算放大器的内部结构非常复杂，它通常包含大量的分离元件。

8A person working with an op-amp does not ordinarily need to be concerned with its internal construction. It is helpful, however, to have some general understanding of what the internal circuitry accomplishes.使用运算放大器工作的人一般并不需要关心其内部结构。

然而，了解其内部电路所具备功能的一般常识是很有帮助地。

9This permits the user to see how the device performs and indicates some of its limitations as a functioning unit.这就让用户明白该器件是怎样工作的，当然也显示出其作为一个功能单元的一些局限。

10The first stage or input of an op-amp is usually a differential amplifier. This amplifier has two inputs, which are labeled V1 and V2.运算放大器的内部结构非常复杂，它通常包含大量的分离元件。

运算放大器的输入或者其第一级通常是一个差分放大器。

该放大器有两个分别标为V1、V2的输入端。

11It provides high gain of the signal difference supplied to the two inputs and low gain for common signals applied to both inputs simultaneously.它对同时施加在两个输入端的差分、共模信号分别提供高、低增益。

12The input impedance is high to any applied signal. The output of the amplifier is generally two signals of equal amplitude and 180o out of phase. This could be described as a push-pull input and output.对于任意信号，输入阻抗均很大。

它一般输出幅值相同而相位相差180o的两路信号。

这可称为推拉式输入输出。

13Flip-flops are commonly used to generate signals, shape waves, and achieve division.触发器通常用于产生信号、整形波形、实现分频14In addition to these operations, a flip-flop may also be used as a memory device.除此之外，它也可用作存储器件。

15In this capacity, it can be made to hold an output state even when the input is completely removed. It can also be made to change its output when an appropriate input signal occurs. 至于这方面，甚至当输入信号被完全去除时它都能保持输出状态。

当出现合适的输入信号时，也可用它来改变其输出状态。

16In many digital system applications, flip-flops must be set and cleared at specific times with respect to other operation circuits.许多数字应用系统在特定时刻参照其其它运算电路须要求对触发器进行置位、清零。

17This type of operation can be achieved by manipulating flip-flops in step with a clock pulse这类操作可通过逐步控制触发器实现。

18In this case, the appropriate RS inputs and clock pulse must all be present in order to cause a state change. A device of this type is called an RS triggered flip-flop or simply an RST flip-flop.在这种情况下，须要有合适的RS输入信号和时钟脉冲以促使触发器状态的改变。

这种器件就称为RS触发的触发器或者简称为RST触发器。

19One of the most versatile and important logic devices of digital system is the counter. This device, as a general rule, can be employed to count a wide varity of objects in a number of different digital system applications.计数器是数字系统的最通用、重要的逻辑器件之一。

作为惯例，它可对许多不同数字应用系统中的大量物体进行计数。

20While this device may be called upon to count an endless number of objects, it essentially counts only one thing, electronic pulses.尽管可以说该器件能对数不清的物体进行计数，本质上，它仅仅对一种物体进行了计数，即电脉冲。

21These pulses may be produced electronically by a clock mechanism, electromechanically, photoelectrically, acoustically, or by a number of other processes. The basic operation of the counter, however, is completely independent of the pulse generator.这些脉冲可由机电式、电子光学式、声音式或许多其它形式的脉冲机构产生。

然而，计数器的基本工作完全独立于这些脉冲产生器。

22A common application of the digital counter is used to count numerical information in binary form.数字计数器的一个普通应用就是对二进制形式的数字信息进行计数。