电子工程系-毕业论文-中英文翻译

1、 滨江学院滨江学院 中英文翻译中英文翻译 题题 目目 一个声音效果的振荡发生器 院院 系系 电子信息工程 专专 业业 电子信息工程 学生姓名学生姓名 学学 号号 指导教师指导教师 职职 称称 2 0 1 1 年年 0 3 月月 2 0 日日 A Sound-Effects Generator One way to produce attention-getting sound effects is to control the frequency of an oscillator by means of periodic impulses from a second oscillator.Th

2、is is an ideal role for a pair of 555 timers operated in their astable (free-running) mode. Figure 1 show how two 555 s are connected to provide sound effects.The first 555(IC1)is connected as an oscillator with an adjustable period of a few tens of hertz or less.The second 555(IC2)is connected as a

3、 voltage-controlled oscillator(vco)with an adjustable frequency of a few hundred to a few thousand hertz. Capacitor C2is the key to the unique sounds produced by the circuit,as let s assume for a moment that C2 is not present.Then IC2 will oscillate at a fixed frequency determined by the voltage at

4、pin3 of IC1.Negative going 10-millisecond pulses from IC1 will pruduce brief,click-like interruptions or changes in IC2 s frequency of oscillation. Now let s return C2 to the circuit.During intervals between negative going pulses from IC1,IC2 changes through R3 to the voltage at pin3 of IC1.The rela

5、tively slow charging rate of C2 produces a gradual decrease in IC2 s oscillation frequency.When IC1 switches C2 is immediately discharged and the frequency of IC2 is suddenly increased.Capacitor C2,then begins to rechange,as shown in the oscillogram is Fig.2,and the cycle repeats.The resulting sound

6、s from the speaker are far more interesting than the rather boring interrupted tone sequence produced when C2 is not present. For best results,use proten tio metors with knobs for R1 and R5.This will enable you to quickly change the ciucuit s cycle rate(via R1)and its tone frequency(via R5).A faster

7、 cycle rate resembles the sound of a chirping bird. A slower one makes a good warning alarm. Be sure to experiment with the values of R3 and C2.Increasing C2 stretches the time required for IC2 s tone to fall from its highest to its lowest frequency.Increasing R3 has a similar effect.If the values f

8、or C2 or R3 are too high,C2 will not fully charge during each cycle,thus reducing the dynamic range of the circuit s tone frequency. Incidentally,note that Fig.1 specifies either a 7555 or 555 for IC1 and IC2.The 7555 is CMOS counterpart of the 555.It consumes much less power and can operate form a

9、lower voltage(less than 3 volts)than the standard 555.It also has a higher oscillation frequency. I ll have more to say about this important new chip in future columns.In the meantime,this project is an excellent way to become acquainted with either the 555 or the 7555. R 4 DC 7 Q 3 GND 1 VCC 8 TR 2

10、 TH 6 CV 5 IC1 555 R 4 DC 7 Q 3 GND 1 VCC 8 TR 2 TH 6 CV 5 IC2 555 R1 100K R5 100K R2 1k R3 22k R4 220 R6 1k C1 4.7uF C2 2.2uF C3 4.7uF DC VALUE=9 Fig.1. sound-effects generator circuit Fig.2. oscillogram showing effect of charge on C2 on the output of IC1 一种声音效果的振荡发生器 一种产生明显声音效果的方法是利用第二个振荡器产生的周期脉冲去

11、控制一个振荡器的频率。这是一 种工作在它们非稳态（自由运行）工作状态的理想 555 定时器。 图 1 显示了两个 555 定时器怎样联系在一起产生声音效果。第一个 555（IC1）作为几十赫兹或更少频 率可调的振荡器连接在电路中，第二个 555（IC2）则是作为一个从几百到几千频率可调的电压控制器工作 于电路中。 电容 C2 是电路中产生独特声音的关键，让我们假设 C2 现在不存在，则 IC2（第二个 555）将振荡在 一个固定的频率，该频率由 IC1 的 3 引脚输出的电压决定。从 IC1 流过的负向 10 毫秒脉冲将生成简单 的像单击中断或 IC2 的频率振荡的变化。 现在将 C2 回到电

12、路当中来，在 IC1 负向脉冲之间的时间间隔内，IC2 由连接在 IC13 引脚电压的变化 而决定着。较慢充电率电容 C2 将在 IC 上产生出逐渐减少的振荡频率。当 IC1 开关，C2 将直接放电同时 IC2 上的频率将突然增加。然后电容 C2 将重新充电，由图 2 显示，而且呈周期显示。由此产生的声音从演 讲者更有趣多了口气相当枯燥乏味时产生中断序列 C2 已不存在。 为了获得最佳效果，需利用电位器 R1、R5 的旋钮进行操作。这将使您能够快速更改电路的周期率（通 过 R1）和音频率（通过 R5）。一个较快的循坏率听起来像鸟叫，慢的则产生一个良好的预警警报。 请务必对 R3 和 C2 进行测试，增大 C2，延伸 IC2 的音调从上往下坠落的最高的最低点频率所需要的 时间。有一种相似的效应增加 R3 线。如果该数值为 C2 或 R3 过高,C2 将不会完全费用在每个周期,因而减 少了动态范围的电路的音频。 顺便说一下，注意图 1 中无论是 7555 或指定为 IC1 的 555 和 IC2.7555 是 CMOS 型的 555.它只需消耗 更少功率，并且能形成一个较低的电压超过标准 555（小于 3 伏）。同时，它也具有较高的振荡频率。 我还会有更多要说这个重要的新芯片，在未来的专栏。在此期间，这个项目是一种优秀的方法来熟悉 555 或 7555。 R 4 DC 7