【正文】
also has the timing, timing and alarm function. The default host for switching the default answer time by time, the system will plete the automatic countdown. If the stipulated time someone vies to answer first, then the time will automatically stop。該搶答器主要運用到了編碼器,譯碼器和鎖存器:它采用74LS148來實現搶答器的選號,采用74LS279芯片實現對號碼的鎖存,采用74LS192實現十進制的減法計數,采用555芯片產生秒脈沖信號來共同實現倒計時功能,采用74LS121單穩(wěn)態(tài)芯片來實現報警信號的輸出。主持人通過時間預設開關預設供搶答的時間,系統(tǒng)將完成自動倒計時。 學 年 論 文基于Allegro SPB的八路搶答器電路板的 設計與仿真Based on the Allegro SPB Eightchannel responder circuit board design and simulation 【摘要】介紹了數碼顯示八路搶答器電路的組成、設計及功能,電路采用74系列常用集成電路進行設計。該搶答器除具有基本的搶答功能外,還具有定時、計時和報警功能。若在規(guī)定的時間內有人搶答,則計時將自動停止;若在規(guī)定的時間內無人搶答,則系統(tǒng)中的蜂鳴器將發(fā)響,提示主持人本輪搶答無效,實現報警功能,若超過搶答時間則搶答無效。通過課程設計提高和鞏固了所學的專業(yè)知識,以及知識的綜合應用和焊接技術。 if nobody answer the question on time, the system will send the buzzer rang, indicating that the host this contest null and void, realize alarm function, if more than the answer answer invalid time.The responder is used mainly to the encoder, decoder and latch: it uses 74LS148 to achieve Responder selection, the number of latches using 74LS279 chip, using 74LS192 to achieve the subtraction counting decimal, using 555 chip to produce the second pulse signal to realize the countdown function, to achieve the output alarm signal using 74LS121 monostable chip.Through courses designed to enhance and consolidate the knowledge of professional knowledge, as well as the synthesis and application of knowledge of welding technology.[ keywords ] Responder coding decoding timing alarm 目 錄引 言 1一 八路搶答器設計與要求 2二 八路搶答器電路原理和設計 2 八路競賽搶答器原理 2 八路競賽搶答器電路框圖 2 搶答電路 3 報警電路 6 時序控制電路 6 電路設計仿真 8三 主要芯片介紹 9 74LS148芯片 9 74LS279芯片 10 74LS121芯片 11 74LS48芯片 12四 電路實驗與調試 14 焊接 14 靜態(tài)檢測 15 動態(tài)調試 15 調試中出現的問題與解決