電(dian)阻(zu)通常都采用(yong)色(se)環(huan)標(biao)示(shi)(shi)(shi)(shi)法(fa)。色(se)標(biao)法(fa)就是(shi)用(yong)棕(zong)(zong)、紅(hong)、橙、黃、綠(lv)、蘭、紫、灰、白、黑十種顏色(se)代(dai)表(biao)(biao)(biao)1234567890十個阿拉伯(bo)數(shu)字，金、銀兩種顏色(se)代(dai)表(biao)(biao)(biao)倍(bei)率0.1、0.01或(huo)誤差(cha)5%、10%.套件中附有(you)顏色(se)樣本的實(shi)物和(he)多(duo)款色(se)環(huan)電(dian)阻(zu)常見的四(si)道色(se)環(huan)要讀取三(san)位有(you)效數(shu)字，一二位表(biao)(biao)(biao)示(shi)(shi)(shi)(shi)有(you)效數(shu)，第三(san)位表(biao)(biao)(biao)示(shi)(shi)(shi)(shi)倍(bei)率。例：黃紫紅(hong)金，三(san)位有(you)效數(shu)為(wei)472,表(biao)(biao)(biao)示(shi)(shi)(shi)(shi)47乘(cheng)以(yi)102（或(huo)加兩個0）等于(yu)4700,即4.7K歐(ou)姆；再如：棕(zong)(zong)黑黑金，三(san)位有(you)效數(shu)為(wei)100,表(biao)(biao)(biao)示(shi)(shi)(shi)(shi)10乘(cheng)以(yi)100（或(huo)加0個0）等于(yu)10,即10歐(ou)姆。
在實驗進程中，如(ru)果(guo)三極(ji)管(guan)的基(ji)極(ji)和其它引腳間(jian)不(bu)具備有單向(xiang)(xiang)導電特(te)性的（或說單向(xiang)(xiang)導電特(te)性不(bu)明顯），就說明三極(ji)管(guan)是(shi)壞(huai)的；另(ling)外，即使單向(xiang)(xiang)導電特(te)性正常，但不(bu)能(neng)(neng)受(shou)基(ji)極(ji)控制(zhi)或不(bu)穩定(ding)，也(ye)說明三極(ji)管(guan)是(shi)壞(huai)的，或性能(neng)(neng)很(hen)差。
可控(kong)(kong)(kong)(kong)硅在控(kong)(kong)(kong)(kong)制(zhi)極加上合適的觸發電流，可控(kong)(kong)(kong)(kong)硅就能夠從斷開(kai)狀態變(bian)成為導(dao)通狀態，這時(shi)，我(wo)們(men)取消控(kong)(kong)(kong)(kong)制(zhi)極的觸發電流，但可控(kong)(kong)(kong)(kong)硅仍(reng)然(ran)能維持導(dao)通狀態。如果流過可控(kong)(kong)(kong)(kong)硅的電流開(kai)始變(bian)小(xiao)，當小(xiao)于維持導(dao)通的能力時(shi)，可控(kong)(kong)(kong)(kong)硅才關斷，直到下次觸發時(shi)才會(hui)導(dao)通。
