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)閃(shan)爍燈(deng).提(ti)醒聽力不(bu)太好的(de)老年人及時(shi)(shi)接電(dian)(dian)(dian)話(hua)(hua)，因電(dian)(dian)(dian)話(hua)(hua)摘機后LED燈(deng)會(hui)熄(xi)滅，還能(neng)幫你及時(shi)(shi)發現電(dian)(dian)(dian)話(hua)(hua)是否被(bei)他人盜(dao)打，同(tong)時(shi)(shi)也具(ju)有一定的(de)防雷擊保(bao)護(hu)作(zuo)用。不(bu)過由于該產(chan)品使用的(de)是電(dian)(dian)(dian)話(hua)(hua)所(suo)屬的(de)電(dian)(dian)(dian)信機房饋電(dian)(dian)(dian)電(dian)(dian)(dian)源，使用時(shi)(shi)一旦(dan)索(suo)取電(dian)(dian)(dian)流(liu)過大難免會(hui)影響電(dian)(dian)(dian)話(hua)(hua)撥(bo)打和傳(chuan)真收發，特別是ADSL寬帶用戶撥(bo)號上(shang)網時(shi)(shi)容易造成(cheng)頻繁(fan)掉線(xian)。圖3是電(dian)(dian)(dian)話(hua)(hua)線(xian)LED燈(deng)電(dian)(dian)(dian)路工(gong)作(zuo)原理圖，36V或48V的(de)電(dian)(dian)(dian)話(hua)(hua)線(xian)路直(zhi)流(liu)電(dian)(dian)(dian)壓(ya)經(jing)10kΩ限(xian)(xian)流(liu)電(dian)(dian)(dian)阻(zu)并由4個(ge)二(er)極管(或整流(liu)橋)作(zuo)極性變換后加在LED上(shang)，當電(dian)(dian)(dian)話(hua)(hua)饋電(dian)(dian)(dian)電(dian)(dian)(dian)壓(ya)為(wei)(wei)36V時(shi)(shi)，實測工(gong)作(zuo)電(dian)(dian)(dian)流(liu)約1.2mA，亮度偏低，把限(xian)(xian)流(liu)電(dian)(dian)(dian)阻(zu)換成(cheng)5.6kΩ時(shi)(shi)工(gong)作(zuo)電(dian)(dian)(dian)流(liu)升為(wei)(wei)2.1mA：亮度稍微有些增(zeng)加。

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考慮到電話線LED燈對(dui)上網存在不(bu)利(li)影響，不(bu)能經常接在電(dian)話線上，筆者又對(dui)該燈進行了一番改(gai)(gai)(gai)造，改(gai)(gai)(gai)造后的(de)電(dian)路原理圖(tu)如(ru)圖(tu)4所(suo)示(shi)，把(ba)中間(jian)的(de)6顆LED改(gai)(gai)(gai)成并(bing)聯，同時增加一塊3.6V的(de)手機(ji)鋰離子電(dian)池(chi)，平時使(shi)用內置的(de)新增鋰電(dian)工作(zuo)，當限流(liu)電(dian)阻為5.6Ω時，工作(zuo)電(dian)流(liu)約120mA，亮度比較令(ling)人滿意。緊急情況下仍(reng)可(ke)采用插入電(dian)話分機(ji)接口(kou)照明，改(gai)(gai)(gai)造后的(de)工作(zuo)電(dian)流(liu)約4.6mA，亮度還算說得過去。

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自帶鉛酸蓄電池能充電的LED燈：

根(gen)據實物畫出的(de)電(dian)(dian)(dian)(dian)路(lu)工作原理圖如圖5所示，220V交流(liu)市電(dian)(dian)(dian)(dian)經電(dian)(dian)(dian)(dian)容降壓、二極管整流(liu)后給鉛酸蓄電(dian)(dian)(dian)(dian)池充(chong)電(dian)(dian)(dian)(dian)，紅色LED作充(chong)電(dian)(dian)(dian)(dian)指示。充(chong)好電(dian)(dian)(dian)(dian)后使(shi)用(yong)時(shi)閉合(he)按鈕(niu)開關K，將首先接通3顆彩色閃(shan)爍LED，發出夢幻(huan)般(ban)變化莫測的(de)七(qi)彩光(guang)芒，在夜間平添一些生(sheng)活樂趣，再按一下開關K則關閉彩色閃(shan)爍LED，接著再按才會接通24顆并聯的(de)高(gao)亮LED，由(you)于數目較多(duo)，照明效果很好。

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當鉛酸電池電(dian)(dian)壓(ya)為(wei)4V時(shi)，實(shi)測彩燈工作(zuo)電(dian)(dian)流(liu)(liu)約60mA，高(gao)亮(liang)LED電(dian)(dian)流(liu)(liu)竟(jing)達(da)600多mA。這(zhe)樣大(da)的(de)電(dian)(dian)流(liu)(liu)不僅使(shi)得每次充(chong)滿電(dian)(dian)后(hou)照明(ming)時(shi)間不會(hui)太長(chang)，而且會(hui)對(dui)電(dian)(dian)池內部結(jie)構造成損傷，縮(suo)短(duan)使(shi)用壽命，因此(ci)必(bi)須給(gei)高(gao)亮(liang)LED串入一個小阻值限流(liu)(liu)電(dian)(dian)阻，經多次試驗選定1.2Ω時(shi)工作(zuo)電(dian)(dian)流(liu)(liu)最終降(jiang)為(wei)320mA，而亮(liang)度變化(hua)不太明(ming)顯(xian)，因該(gai)款(kuan)燈改動不大(da)，改造后(hou)的(de)電(dian)(dian)路原理圖省略。

通過(guo)以上(shang)剖(pou)析發(fa)現，市場上(shang)出售的各(ge)種LED燈電路大多過(guo)于簡單，雖(sui)說價格十分便宜，但在(zai)客觀(guan)上(shang)仍會造成(cheng)能(neng)源浪費，只有經(jing)過(guo)一(yi)番(fan)合理(li)改進，才能(neng)既保(bao)留(liu)它經(jing)濟便攜的優點，又有效地提高使用安全性和可(ke)靠性。