LED應急燈電路圖

電話線LED燈：

又稱免電燈(即網上賣家俗稱的緬甸燈)，因為它采用普通家用固定電話的進線電壓做電源，無需電池或交流市電，把尾部的水晶頭插入電話分機接口即可照明，不用另交電費，也不用擔心停電。此外還能兼作電話來(lai)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)閃爍燈(deng).提醒聽力不太好(hao)的老(lao)年人(ren)及時(shi)接(jie)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)話，因電(dian)(dian)(dian)(dian)(dian)(dian)(dian)話摘機后(hou)LED燈(deng)會熄滅，還能(neng)幫(bang)你及時(shi)發現電(dian)(dian)(dian)(dian)(dian)(dian)(dian)話是(shi)(shi)否被他人(ren)盜打，同(tong)時(shi)也具有(you)一定的防雷擊保護作(zuo)用(yong)(yong)。不過(guo)由(you)于該產品使用(yong)(yong)的是(shi)(shi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)話所屬(shu)的電(dian)(dian)(dian)(dian)(dian)(dian)(dian)信機房(fang)饋(kui)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)，使用(yong)(yong)時(shi)一旦索取電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)過(guo)大難免會影(ying)響電(dian)(dian)(dian)(dian)(dian)(dian)(dian)話撥打和(he)傳真收發，特別是(shi)(shi)ADSL寬帶用(yong)(yong)戶撥號上網時(shi)容易造(zao)成頻繁掉線(xian)。圖3是(shi)(shi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)話線(xian)LED燈(deng)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路工作(zuo)原理(li)圖，36V或48V的電(dian)(dian)(dian)(dian)(dian)(dian)(dian)話線(xian)路直流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓經(jing)10kΩ限流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)并由(you)4個二(er)極管(或整流(liu)(liu)橋)作(zuo)極性變換后(hou)加在LED上，當(dang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)話饋(kui)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓為(wei)36V時(shi)，實測工作(zuo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)約1.2mA，亮度偏低，把(ba)限流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)換成5.6kΩ時(shi)工作(zuo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)升為(wei)2.1mA：亮度稍微(wei)有(you)些(xie)增加。

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考慮到電話線LED燈對(dui)上網存在不利影響，不能經(jing)常接在電(dian)(dian)(dian)話(hua)線(xian)上，筆者又對(dui)該燈進行了(le)一番改(gai)(gai)造，改(gai)(gai)造后(hou)的(de)電(dian)(dian)(dian)路原理圖(tu)如圖(tu)4所(suo)示，把中間的(de)6顆LED改(gai)(gai)成并聯，同時(shi)增(zeng)(zeng)加一塊3.6V的(de)手(shou)機鋰(li)離子電(dian)(dian)(dian)池(chi)，平時(shi)使用內置的(de)新增(zeng)(zeng)鋰(li)電(dian)(dian)(dian)工(gong)作(zuo)，當限流(liu)(liu)電(dian)(dian)(dian)阻為5.6Ω時(shi)，工(gong)作(zuo)電(dian)(dian)(dian)流(liu)(liu)約(yue)120mA，亮度比(bi)較令人滿意。緊急情況下仍可采用插(cha)入(ru)電(dian)(dian)(dian)話(hua)分機接口照明，改(gai)(gai)造后(hou)的(de)工(gong)作(zuo)電(dian)(dian)(dian)流(liu)(liu)約(yue)4.6mA，亮度還算(suan)說得(de)過(guo)去。

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自帶鉛酸蓄電池能充電的LED燈：

根據實(shi)物畫(hua)出(chu)的(de)(de)電(dian)(dian)路工(gong)作(zuo)原理圖如圖5所示，220V交流市電(dian)(dian)經電(dian)(dian)容降壓、二極管整流后給鉛(qian)酸(suan)蓄(xu)電(dian)(dian)池充電(dian)(dian)，紅色LED作(zuo)充電(dian)(dian)指示。充好(hao)電(dian)(dian)后使用時(shi)閉合按鈕開關(guan)K，將首先接通(tong)3顆(ke)彩色閃爍LED，發出(chu)夢(meng)幻般變化莫測的(de)(de)七彩光芒(mang)，在夜間平添(tian)一些生(sheng)活樂(le)趣，再按一下(xia)開關(guan)K則關(guan)閉彩色閃爍LED，接著再按才會接通(tong)24顆(ke)并聯的(de)(de)高亮(liang)LED，由(you)于(yu)數目較多，照明效(xiao)果(guo)很好(hao)。

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當鉛酸電池電壓為(wei)(wei)4V時，實測彩燈(deng)工(gong)作電流(liu)(liu)(liu)約60mA，高(gao)亮LED電流(liu)(liu)(liu)竟(jing)達(da)600多mA。這(zhe)樣大的電流(liu)(liu)(liu)不(bu)僅使得每(mei)次充滿(man)電后照明(ming)時間不(bu)會(hui)太長(chang)，而(er)且會(hui)對電池(chi)內部(bu)結(jie)構造(zao)成損傷，縮短使用(yong)壽命，因此必須給(gei)高(gao)亮LED串入一個小(xiao)阻值限流(liu)(liu)(liu)電阻，經多次試驗選定(ding)1.2Ω時工(gong)作電流(liu)(liu)(liu)最終降為(wei)(wei)320mA，而(er)亮度(du)變化不(bu)太明(ming)顯，因該款燈(deng)改(gai)動不(bu)大，改(gai)造(zao)后的電路原理圖省略。

通過(guo)以上剖析(xi)發現，市場(chang)上出售的(de)各(ge)種LED燈電(dian)路(lu)大多過(guo)于簡單，雖說價格(ge)十分(fen)便(bian)宜，但(dan)在(zai)客觀上仍會(hui)造成能(neng)源浪費，只有(you)(you)經過(guo)一(yi)番合理(li)改進(jin)，才能(neng)既(ji)保留它經濟便(bian)攜的(de)優點，又有(you)(you)效地提(ti)高使用安全性和可靠性。