60秒计时器课程设计 周海祥.docVIP

目录 摘要······························································2 引言······························································2 设计目的·····················································2 设计任务·····················································2 电路原理设计·················································2 3-1计时器的设计原理··········································2 3-2计时器的基本逻辑功能······································3 3-3主干电路设计··············································3 3-3-1震荡电路设计··········································3 3-3-2计数器的设计··········································3 3-3-3译码器的设计··········································3 四．电路仿真······················································4 五．系统分析······················································5 5-1基础元件介绍··············································5 5-1-1计数器················································5 5-1-2译码器与显示管········································6 5-1-3振荡器················································8 5-1-4与非门················································8 六．电路的焊接···················································9 七．调试·························································9 八．总结·························································10 参考文献·························································10 致谢·····························································10 附录·····························································11 74LS160构成的60秒计时器 摘要 60秒计时器是采用数字电路实现的数字显示计时装置。本系统由振荡器，计数器，译码器，LED显示器组成。采用74LS系列中小规模集成芯片。 引言 计时器是用数字集成电路做成的现代计时器，与传统的机械钟相比，它具有走时准确完成由74LS160构成的60秒计时器 计时器的组成:60秒计时器一般由振荡器，计时器，译码器，LED显示器组成，这些都是数字电路中应用最广泛的基本电路。 三.电路原理设计 3-1 计时器的设计原理： 先构成一个555定时器和分频器产生震荡周期为一秒的标准“秒”脉冲信号，由74LS160采用清零法分别组成六十进制的“秒”计数器。清零法适用于有异步置零输入端的集成计数器 3-3主干电路设计 3-3-1震荡电路设计： 主要用来产生时间的标准信号，精确程度就取决于时间的标准信号的频率及稳定性。秒”信号产生器是整个系统的时基信号，在此用555定时器来实现。将555定时器与电阻、电容按照555定时器构成振荡器，组成一个输出1Hz的脉冲信号，将该标准“秒”信号送入“秒”计数器。“秒”计数器采用60进制计数法，其是由2片74LS160采用反馈置数法串联而成连接如下图： 3-3-2计数器的设计： 由秒个