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電(dian)(dian)(dian)閃(shan)爍燈.提(ti)醒(xing)聽力不(bu)(bu)太好的(de)(de)老年人及時(shi)接電(dian)(dian)(dian)話，因電(dian)(dian)(dian)話摘機后LED燈會(hui)熄滅(mie)，還能幫你(ni)及時(shi)發現(xian)電(dian)(dian)(dian)話是否被他(ta)人盜打(da)，同時(shi)也具有(you)一(yi)定的(de)(de)防雷(lei)擊保護作用(yong)。不(bu)(bu)過由于該(gai)產品(pin)使用(yong)的(de)(de)是電(dian)(dian)(dian)話所屬的(de)(de)電(dian)(dian)(dian)信機房(fang)饋(kui)電(dian)(dian)(dian)電(dian)(dian)(dian)源，使用(yong)時(shi)一(yi)旦索取電(dian)(dian)(dian)流(liu)過大難免會(hui)影響電(dian)(dian)(dian)話撥打(da)和傳真收發，特別(bie)是ADSL寬帶用(yong)戶撥號(hao)上(shang)網時(shi)容(rong)易(yi)造成頻繁掉線。圖3是電(dian)(dian)(dian)話線LED燈電(dian)(dian)(dian)路(lu)工作原(yuan)理圖，36V或48V的(de)(de)電(dian)(dian)(dian)話線路(lu)直(zhi)流(liu)電(dian)(dian)(dian)壓(ya)經10kΩ限流(liu)電(dian)(dian)(dian)阻并由4個二極管(或整流(liu)橋)作極性變換后加在LED上(shang)，當電(dian)(dian)(dian)話饋(kui)電(dian)(dian)(dian)電(dian)(dian)(dian)壓(ya)為36V時(shi)，實測工作電(dian)(dian)(dian)流(liu)約1.2mA，亮(liang)度(du)偏低(di)，把限流(liu)電(dian)(dian)(dian)阻換成5.6kΩ時(shi)工作電(dian)(dian)(dian)流(liu)升為2.1mA：亮(liang)度(du)稍(shao)微有(you)些增加。

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考慮到電話線LED燈對上網存(cun)在不(bu)利(li)影(ying)響，不(bu)能(neng)經常接在電(dian)(dian)話線上，筆者又(you)對該燈進行了(le)一番改(gai)造，改(gai)造后(hou)的(de)(de)電(dian)(dian)路(lu)原(yuan)理圖(tu)如圖(tu)4所示，把中間的(de)(de)6顆LED改(gai)成并聯(lian)，同時(shi)增(zeng)(zeng)加(jia)一塊3.6V的(de)(de)手(shou)機(ji)鋰(li)(li)離子電(dian)(dian)池(chi)，平時(shi)使(shi)用(yong)內置的(de)(de)新增(zeng)(zeng)鋰(li)(li)電(dian)(dian)工作，當限(xian)流(liu)電(dian)(dian)阻為5.6Ω時(shi)，工作電(dian)(dian)流(liu)約120mA，亮度(du)比較令(ling)人滿意。緊急情況下仍(reng)可采用(yong)插入電(dian)(dian)話分機(ji)接口照(zhao)明(ming)，改(gai)造后(hou)的(de)(de)工作電(dian)(dian)流(liu)約4.6mA，亮度(du)還算(suan)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(shi)物畫出(chu)的電(dian)(dian)(dian)路工作原(yuan)理圖如(ru)圖5所示(shi)，220V交流市電(dian)(dian)(dian)經電(dian)(dian)(dian)容降(jiang)壓、二(er)極管整流后給鉛酸蓄(xu)電(dian)(dian)(dian)池充(chong)電(dian)(dian)(dian)，紅色LED作充(chong)電(dian)(dian)(dian)指示(shi)。充(chong)好(hao)電(dian)(dian)(dian)后使(shi)用時閉(bi)(bi)合按(an)(an)鈕開(kai)關(guan)K，將首先接(jie)通3顆(ke)彩(cai)(cai)色閃(shan)爍LED，發(fa)出(chu)夢(meng)幻般變化莫測的七彩(cai)(cai)光芒，在夜(ye)間平添一些生活(huo)樂趣，再按(an)(an)一下開(kai)關(guan)K則關(guan)閉(bi)(bi)彩(cai)(cai)色閃(shan)爍LED，接(jie)著再按(an)(an)才會(hui)接(jie)通24顆(ke)并(bing)聯(lian)的高亮LED，由于(yu)數(shu)目較(jiao)多，照明效果很好(hao)。

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當鉛酸電池電(dian)(dian)壓(ya)為(wei)4V時，實測彩(cai)燈工作電(dian)(dian)流(liu)約60mA，高(gao)亮(liang)LED電(dian)(dian)流(liu)竟達600多(duo)(duo)mA。這樣大(da)的電(dian)(dian)流(liu)不僅使(shi)得每次(ci)充滿電(dian)(dian)后照明時間(jian)不會太(tai)長，而且會對電(dian)(dian)池內部結構(gou)造成損傷，縮短使(shi)用壽命，因(yin)此必須給(gei)高(gao)亮(liang)LED串入(ru)一個小阻(zu)值限流(liu)電(dian)(dian)阻(zu)，經多(duo)(duo)次(ci)試驗選定1.2Ω時工作電(dian)(dian)流(liu)最終降為(wei)320mA，而亮(liang)度變化(hua)不太(tai)明顯，因(yin)該款燈改(gai)動不大(da)，改(gai)造后的電(dian)(dian)路原理圖(tu)省略。

通過以上剖析(xi)發現，市場上出售的各種LED燈電(dian)路(lu)大多過于簡(jian)單，雖說價(jia)格十分便(bian)宜，但在客觀(guan)上仍(reng)會造成能(neng)源浪費，只(zhi)有經(jing)過一番合(he)理改(gai)進，才能(neng)既保留它(ta)經(jing)濟便(bian)攜的優點(dian)，又有效地提高(gao)使用安全性和(he)可(ke)靠性。