基于數(shù)字電路的電子秒表課程設(shè)計(jì)(文件)
【正文】 發(fā)器用集成與非門構(gòu)成基本RS觸發(fā)器，屬低電平直接觸發(fā)的觸發(fā)器，有直接置位、復(fù)位的功能。它的數(shù)字形式如下圖所示：圖14 七段顯示數(shù)碼管數(shù)碼管的每一段是一個發(fā)光二極管，按發(fā)光二極管的連接方式可分為共陰極和共陰極兩種。 圖8 一百分頻電路圖②六十分頻電路如下圖所示：一級十分頻電路與一級六分頻電路串聯(lián)，形成串行進(jìn)位計(jì)數(shù)，其內(nèi)部級聯(lián)與一百進(jìn)制相同,時鐘脈沖均為低位的進(jìn)位端通過一非門接至高位的CLK端。如下圖所示：圖6 十分頻器電路圖（3） 使用芯片74LS160構(gòu)成6進(jìn)制計(jì)數(shù)器由74LS160組成的六分頻電路如下圖所示電路，給CLK以點(diǎn)動單脈沖或頻率較低的連續(xù)脈沖，Q端接發(fā)光二極管，觀察發(fā)光二極管的狀態(tài)。集成芯片74LS160，其管腳排列如圖所示。74LS00的3號管腳輸出接至U1（最低位十進(jìn)制計(jì)數(shù)器74LS160）的時鐘輸入端作為時鐘分頻計(jì)數(shù)的基本時鐘。（2）用555定時器構(gòu)成方波發(fā)生器電路如下圖所示。5腳：VC為控制電壓端。8腳：外接電源VCC， ~ 16V，CMOS型時基電路VCC的范圍為3 ~ 18V。在選擇數(shù)碼顯示管時，可以利用六個數(shù)碼管；也可以借鑒簡易數(shù)字頻率計(jì)中的四位數(shù)碼管來顯示后四位，再用兩個數(shù)碼管顯示分鐘的兩位。計(jì)數(shù)脈沖是由555定時器構(gòu)成的多諧振蕩器，產(chǎn)生100赫茲脈沖。 1秒，那么我們需要相應(yīng)頻率的信號發(fā)生器。石英晶振蕩器精度很高，一般都需要多級分頻。由于秒表計(jì)數(shù)的需要，故要在電路上加一個控制電路，該控制電路清零、啟動計(jì)時、暫停及繼續(xù)計(jì)數(shù)等控制功能，同時需要一個分頻電路把100kHZ分成100HZ的時間信號達(dá)到準(zhǔn)確穩(wěn)定。關(guān)鍵詞：計(jì)時 精度 計(jì)數(shù)器 顯示器 Abstract Electronic stopwatch is the realization of a digital circuit technology,.It can realize the hour, minute, second does not have mechanical means and has a longer life, so it has been widely used. The principle is a typical digital circuit, which includes a bination logic circuit and a timing circuit. The experiments can be done by electronic stopwatch constituted by the signal system and timing system, and has cleared pause function. Due to the need of a more stable signal, the signal generating system is constituted by the 555 Timer with the resistors and capacitors, and the signal frequency is 100Hz. Timing system contains the counter, decoder, display. Counter 74 LS160 constituted by the decimal counter the decimal and sexagesimal counter, which uses asynchronous binary. The decoder from 74LS48 constitute display digital tube constitute Cle
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