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)閃爍燈(deng).提(ti)醒聽(ting)力不太好的(de)老(lao)年人(ren)及時(shi)接電(dian)(dian)(dian)話(hua)(hua)(hua)，因電(dian)(dian)(dian)話(hua)(hua)(hua)摘機后LED燈(deng)會熄滅，還(huan)能(neng)幫你及時(shi)發(fa)現電(dian)(dian)(dian)話(hua)(hua)(hua)是(shi)否被他人(ren)盜打，同時(shi)也(ye)具(ju)有一(yi)定的(de)防雷擊保(bao)護作用。不過(guo)由于該產品使用的(de)是(shi)電(dian)(dian)(dian)話(hua)(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)一(yi)旦索取電(dian)(dian)(dian)流(liu)過(guo)大(da)難免會影響電(dian)(dian)(dian)話(hua)(hua)(hua)撥打和(he)傳真收發(fa)，特別(bie)是(shi)ADSL寬帶用戶撥號上(shang)網(wang)時(shi)容易造(zao)成(cheng)頻繁(fan)掉(diao)線(xian)(xian)(xian)。圖3是(shi)電(dian)(dian)(dian)話(hua)(hua)(hua)線(xian)(xian)(xian)LED燈(deng)電(dian)(dian)(dian)路(lu)工作原理圖，36V或48V的(de)電(dian)(dian)(dian)話(hua)(hua)(hua)線(xian)(xian)(xian)路(lu)直流(liu)電(dian)(dian)(dian)壓經10kΩ限(xian)流(liu)電(dian)(dian)(dian)阻(zu)并由4個(ge)二極管(或整流(liu)橋)作極性變換(huan)后加在(zai)LED上(shang)，當(dang)電(dian)(dian)(dian)話(hua)(hua)(hua)饋電(dian)(dian)(dian)電(dian)(dian)(dian)壓為(wei)36V時(shi)，實測工作電(dian)(dian)(dian)流(liu)約1.2mA，亮(liang)度偏低，把限(xian)流(liu)電(dian)(dian)(dian)阻(zu)換(huan)成(cheng)5.6kΩ時(shi)工作電(dian)(dian)(dian)流(liu)升為(wei)2.1mA：亮(liang)度稍微(wei)有些增加。

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考慮到電話線LED燈對上(shang)網(wang)存在不(bu)利影(ying)響(xiang)，不(bu)能經常(chang)接(jie)在電(dian)話(hua)線(xian)上(shang)，筆者又對該(gai)燈進(jin)行了(le)一番改造(zao)，改造(zao)后的(de)電(dian)路原理圖(tu)如圖(tu)4所(suo)示，把中(zhong)間(jian)的(de)6顆LED改成并(bing)聯(lian)，同時(shi)增(zeng)加一塊(kuai)3.6V的(de)手機鋰(li)離(li)子電(dian)池，平時(shi)使用內置的(de)新增(zeng)鋰(li)電(dian)工作(zuo)(zuo)，當限流電(dian)阻為5.6Ω時(shi)，工作(zuo)(zuo)電(dian)流約120mA，亮度比較(jiao)令人(ren)滿(man)意。緊急情況下仍可采用插入(ru)電(dian)話(hua)分(fen)機接(jie)口(kou)照(zhao)明，改造(zao)后的(de)工作(zuo)(zuo)電(dian)流約4.6mA，亮度還算說得過(guo)去。

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自帶鉛酸蓄電池能充電的LED燈：

根據實物(wu)畫出的電(dian)(dian)(dian)(dian)路(lu)工(gong)作原理圖如圖5所示，220V交(jiao)流市電(dian)(dian)(dian)(dian)經電(dian)(dian)(dian)(dian)容(rong)降壓、二(er)極管整流后給鉛酸蓄電(dian)(dian)(dian)(dian)池充電(dian)(dian)(dian)(dian)，紅色LED作充電(dian)(dian)(dian)(dian)指示。充好電(dian)(dian)(dian)(dian)后使(shi)用時閉合(he)按(an)鈕開關K，將(jiang)首先接通3顆(ke)彩(cai)色閃爍(shuo)LED，發出夢幻般(ban)變化莫測(ce)的七(qi)彩(cai)光芒，在夜(ye)間平添一(yi)(yi)些生活樂(le)趣，再按(an)一(yi)(yi)下(xia)開關K則(ze)關閉彩(cai)色閃爍(shuo)LED，接著再按(an)才會接通24顆(ke)并聯的高亮(liang)LED，由于數目(mu)較(jiao)多，照明效果很好。

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當鉛酸電池電(dian)壓(ya)為4V時(shi)，實(shi)測彩燈工(gong)(gong)作(zuo)電(dian)流(liu)約60mA，高亮LED電(dian)流(liu)竟達600多(duo)mA。這樣大的電(dian)流(liu)不(bu)僅使得(de)每次充滿電(dian)后照明時(shi)間不(bu)會太長，而(er)且會對電(dian)池內部(bu)結構造成損傷，縮短(duan)使用(yong)壽(shou)命(ming)，因此(ci)必須給高亮LED串入一個小(xiao)阻值限流(liu)電(dian)阻，經多(duo)次試驗選定1.2Ω時(shi)工(gong)(gong)作(zuo)電(dian)流(liu)最終降為320mA，而(er)亮度變化不(bu)太明顯，因該(gai)款燈改(gai)動不(bu)大，改(gai)造后的電(dian)路原(yuan)理(li)圖省略。

通過(guo)以(yi)上(shang)(shang)剖析發現，市場上(shang)(shang)出售的各種LED燈電(dian)路大(da)多過(guo)于簡(jian)單，雖說(shuo)價格十分便宜(yi)，但(dan)在客觀上(shang)(shang)仍(reng)會造成(cheng)能源浪費(fei)，只(zhi)有(you)經過(guo)一番(fan)合理(li)改(gai)進(jin)，才能既保留它(ta)經濟便攜的優點，又有(you)效地提高使(shi)用安全性(xing)和可靠(kao)性(xing)。