播種機堵塞報警器的工作原理簡介

播(bo)(bo)種機存在一點(dian)不足，就是在播(bo)(bo)種時(shi)，播(bo)(bo)種機中的(de)小(xiao)麥下(xia)(xia)落管(guan)(guan)道(dao)很容易被小(xiao)麥堵(du)塞(sai)，而人(ren)(ren)們(men)(men)又一時(shi)很難發現，導致人(ren)(ren)機白走一趟(tang)，浪費世間的(de)同(tong)時(shi)無形之中也降(jiang)低了工作效率。這款(kuan)小(xiao)麥播(bo)(bo)種顆粒(li)堵(du)塞(sai)報警器，它能夠(gou)實施監測管(guan)(guan)道(dao)中小(xiao)麥的(de)下(xia)(xia)落情況，管(guan)(guan)道(dao)一旦(dan)被堵(du)塞(sai)，電(dian)路立即發出報警，從而提醒人(ren)(ren)們(men)(men)及時(shi)采取措(cuo)施進(jin)行處(chu)理。

一、電路原理

該報警(jing)電(dian)(dian)(dian)(dian)路(lu)如下圖所示，電(dian)(dian)(dian)(dian)路(lu)采取紅(hong)外線原理(li)，將(jiang)管(guan)道(dao)(dao)中(zhong)小(xiao)麥(mai)的(de)(de)(de)(de)下落(luo)(luo)情況轉(zhuan)換(huan)成電(dian)(dian)(dian)(dian)信號(hao)來控制報警(jing)電(dian)(dian)(dian)(dian)路(lu)。安裝(zhuang)時，注(zhu)意要將(jiang)紅(hong)外發光(guang)管(guan)VD1和接收管(guan)VD2正對著裝(zhuang)于(yu)小(xiao)麥(mai)下落(luo)(luo)管(guan)道(dao)(dao)中(zhong)，使(shi)(shi)(shi)VD1管(guan)發出的(de)(de)(de)(de)紅(hong)外光(guang)正好(hao)照射在(zai)(zai)VD2管(guan)上，這(zhe)樣(yang)閉(bi)合電(dian)(dian)(dian)(dian)源開關，當小(xiao)麥(mai)顆粒在(zai)(zai)管(guan)子(zi)內正常下落(luo)(luo)時，紅(hong)外光(guang)便被小(xiao)麥(mai)顆粒時斷(duan)時續(xu)(xu)的(de)(de)(de)(de)遮(zhe)擋，使(shi)(shi)(shi)得(de)(de)VD2管(guan)的(de)(de)(de)(de)負極(ji)(ji)產生(sheng)一(yi)系列連續(xu)(xu)的(de)(de)(de)(de)負脈(mo)沖，并通過電(dian)(dian)(dian)(dian)容(rong)C1耦(ou)合到電(dian)(dian)(dian)(dian)容(rong)C2的(de)(de)(de)(de)正極(ji)(ji)，從(cong)而使(shi)(shi)(shi)電(dian)(dian)(dian)(dian)容(rong)C2沖不(bu)上電(dian)(dian)(dian)(dian)，VT1三極(ji)(ji)管(guan)基極(ji)(ji)電(dian)(dian)(dian)(dian)壓近似為(wei)(wei)零(ling)，使(shi)(shi)(shi)得(de)(de)時基電(dian)(dian)(dian)(dian)路(lu)555的(de)(de)(de)(de)2腳(jiao)為(wei)(wei)低(di)電(dian)(dian)(dian)(dian)平，同時由于(yu)三極(ji)(ji)管(guan)VT1的(de)(de)(de)(de)作用，只(zhi)要電(dian)(dian)(dian)(dian)容(rong)C2上的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)壓為(wei)(wei)零(ling)，那么(me)電(dian)(dian)(dian)(dian)容(rong)C3也就不(bu)會充上電(dian)(dian)(dian)(dian)，否則三極(ji)(ji)管(guan)VT1導通，也會將(jiang)其放電(dian)(dian)(dian)(dian)，這(zhe)樣(yang)時基電(dian)(dian)(dian)(dian)路(lu)555的(de)(de)(de)(de)2腳(jiao)和6腳(jiao)都為(wei)(wei)低(di)電(dian)(dian)(dian)(dian)平，其3腳(jiao)輸出高電(dian)(dian)(dian)(dian)平，三極(ji)(ji)管(guan)VT2飽和導通，振蕩電(dian)(dian)(dian)(dian)路(lu)不(bu)起(qi)振，揚聲器不(bu)報警(jing)。

當管(guan)道一旦被堵住后，小麥顆粒將(jiang)不再(zai)落下(xia)，從而使(shi)得VD1管(guan)發(fa)出(chu)的(de)紅外現實中照射（或不照射）在(zai)VD2管(guan)上，這(zhe)樣，C1正極(ji)的(de)電(dian)(dian)(dian)平(ping)始(shi)終(zhong)為(wei)高或低，成(cheng)為(wei)一直流信號，它將(jiang)不再(zai)通過(guo)電(dian)(dian)(dian)容C1到達(da)三極(ji)管(guan)VT1基極(ji)，于是電(dian)(dian)(dian)容C2開始(shi)充電(dian)(dian)(dian)，緊接著，C3也隨著C2的(de)充電(dian)(dian)(dian)而充電(dian)(dian)(dian)，很快，電(dian)(dian)(dian)容C2、C3上的(de)電(dian)(dian)(dian)壓(ya)便到達(da)555的(de)反(fan)轉電(dian)(dian)(dian)壓(ya)，555的(de)2腳(jiao)和6腳(jiao)變成(cheng)高電(dian)(dian)(dian)平(ping)，555復位，3腳(jiao)輸出(chu)低電(dian)(dian)(dian)平(ping)，三極(ji)管(guan)VT2截止，啟動(dong)振蕩電(dian)(dian)(dian)路，從而使(shi)揚聲器(qi)發(fa)聲報警。

二、實物調試與安裝
按原理圖連接(jie)好電路(lu)后，閉(bi)合電源開(kai)關k，先用手(shou)(shou)(shou)模(mo)擬小麥顆粒(li)下落，即(ji)將(jiang)手(shou)(shou)(shou)放于VD1管(guan)(guan)與VD2管(guan)(guan)之間(jian)，做上下揮動(dong)，使照射(she)在VD2管(guan)(guan)上的紅外線時(shi)斷(duan)時(shi)通(tong)，這時(shi)，揚(yang)聲(sheng)器應該不會發聲(sheng)，若不然(ran)可適當調(diao)節電位器RP1使其靈(ling)敏度達(da)到最(zui)佳狀態，然(ran)后將(jiang)手(shou)(shou)(shou)停(ting)止揮動(dong)，模(mo)擬管(guan)(guan)道(dao)堵塞(sai)，此時(shi)揚(yang)聲(sheng)器便會發聲(sheng)報警。

安裝實物時，最關鍵的一點就是紅外線對管的安裝，務必將兩管正對安裝于小麥下落的管道中。在播種工作進行時，閉合開關k，然后就可以工作了。對于機動播種機，則可以在播種機的耬齒附近安裝一個壓控開關來代替開關k，這樣，只有當播種機從機動車的懸掛位置放到地面上時，報警器才開始工作，避免了手動控制的麻煩。