电话来电自动灯开关及次数显示电路毕业论文.doc

摘 要 由电容降压整流电路光传感电子开关单稳延时电路实现关键词 Abstract Telephone automatic light switch is at night or in dark room, automatic light time is about 50 seconds, so that the user can conveniently call telephone caller number display; installed in the user when the number of recorded telephone calls. This paper introduced by capacitance voltage-dropping rectification circuit, a light sensing electrical switch, the constable delay circuit and a counter circuit to realize automatic light switch telephone calls and call number display circuit, and the circuit of the scheme selection, design idea and the principle of a detailed analysis and discussion. Through the practice of acceptance testing, the circuit design is correct; the indicators have been steadily reached. Keywords：Telephone automatic lamp Counting decoder 555 timer The optically controlled circuit 目 录 摘 要 Ⅰ Abstract ..Ⅱ 第1章 绪论 ..1 1.1 课题背景 1 1.2 课题的目的和意义 .................2 1.3 设计要求.......................................................................................................2 第2章 方案设计 3 第3章 硬件设计 4 3.1 铃流检测模块 5 3.1.1 光耦合器...............................................................................................5 3.2 负脉冲产生电路 7 3.3 单稳态触发器 7 3.3.1 NE555......................................................................................................9 3.4 光控电路 10 3.4.1 cds光敏电阻........................................................................................11 3.4.2 电路调节.............................................................................................12 3.5 开关驱动电路 12 3.5.1 电磁式继电器.....................................................................................13 3.6 数字显示电路 15 3.6.1 双BCD计数器4518............................................................................16 3.6.2 半导体数码管.....................................................................................18 本章小结 ...20 结 论 21 致 谢 22 参考文献 23 附录 总电路原理图......................................................................