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)(dian)(dian)(dian)閃爍燈(deng)(deng).提醒聽力(li)不太(tai)好的(de)老(lao)年人及(ji)時(shi)(shi)接電(dian)(dian)(dian)(dian)(dian)(dian)話(hua)(hua)，因電(dian)(dian)(dian)(dian)(dian)(dian)話(hua)(hua)摘機后(hou)LED燈(deng)(deng)會熄滅，還能(neng)幫你及(ji)時(shi)(shi)發現電(dian)(dian)(dian)(dian)(dian)(dian)話(hua)(hua)是(shi)否被他人盜打(da)，同時(shi)(shi)也具(ju)有一定的(de)防(fang)雷擊保護作(zuo)用(yong)(yong)。不過(guo)由于該產品使用(yong)(yong)的(de)是(shi)電(dian)(dian)(dian)(dian)(dian)(dian)話(hua)(hua)所屬的(de)電(dian)(dian)(dian)(dian)(dian)(dian)信機房(fang)饋(kui)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)源，使用(yong)(yong)時(shi)(shi)一旦索(suo)取電(dian)(dian)(dian)(dian)(dian)(dian)流過(guo)大難免會影響電(dian)(dian)(dian)(dian)(dian)(dian)話(hua)(hua)撥打(da)和(he)傳真收發，特(te)別是(shi)ADSL寬帶用(yong)(yong)戶撥號上(shang)網時(shi)(shi)容易(yi)造成頻繁掉線。圖(tu)(tu)3是(shi)電(dian)(dian)(dian)(dian)(dian)(dian)話(hua)(hua)線LED燈(deng)(deng)電(dian)(dian)(dian)(dian)(dian)(dian)路工作(zuo)原理圖(tu)(tu)，36V或(huo)48V的(de)電(dian)(dian)(dian)(dian)(dian)(dian)話(hua)(hua)線路直流電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)經10kΩ限流電(dian)(dian)(dian)(dian)(dian)(dian)阻并由4個二極管(或(huo)整流橋)作(zuo)極性變換后(hou)加在LED上(shang)，當電(dian)(dian)(dian)(dian)(dian)(dian)話(hua)(hua)饋(kui)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)為36V時(shi)(shi)，實測工作(zuo)電(dian)(dian)(dian)(dian)(dian)(dian)流約1.2mA，亮度(du)偏低，把限流電(dian)(dian)(dian)(dian)(dian)(dian)阻換成5.6kΩ時(shi)(shi)工作(zuo)電(dian)(dian)(dian)(dian)(dian)(dian)流升為2.1mA：亮度(du)稍微有些增(zeng)加。

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考慮到電話線LED燈對(dui)上(shang)網存在(zai)不利影響，不能(neng)經常接在(zai)電話線上(shang)，筆者又(you)對(dui)該燈進行了一(yi)番改造，改造后(hou)的電路原理圖(tu)如圖(tu)4所(suo)示，把中間的6顆(ke)LED改成并聯，同(tong)時增加(jia)一(yi)塊3.6V的手機鋰離子(zi)電池，平時使用(yong)內(nei)置的新增鋰電工(gong)作(zuo)，當限流(liu)電阻為5.6Ω時，工(gong)作(zuo)電流(liu)約120mA，亮度(du)比較(jiao)令(ling)人滿意(yi)。緊急情況下仍可采用(yong)插入電話分機接口照明，改造后(hou)的工(gong)作(zuo)電流(liu)約4.6mA，亮度(du)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(gen)據實物(wu)畫出的(de)電(dian)路工作原理圖如圖5所示，220V交流市電(dian)經電(dian)容降(jiang)壓、二極管整流后給鉛酸蓄電(dian)池充(chong)(chong)電(dian)，紅色(se)LED作充(chong)(chong)電(dian)指(zhi)示。充(chong)(chong)好(hao)電(dian)后使用時(shi)閉(bi)合按鈕開(kai)(kai)關K，將首先接(jie)通3顆彩色(se)閃(shan)爍(shuo)LED，發出夢幻(huan)般(ban)變(bian)化莫測的(de)七(qi)彩光(guang)芒(mang)，在夜間平添一(yi)些生活樂趣，再(zai)(zai)按一(yi)下開(kai)(kai)關K則關閉(bi)彩色(se)閃(shan)爍(shuo)LED，接(jie)著再(zai)(zai)按才會(hui)接(jie)通24顆并聯(lian)的(de)高(gao)亮(liang)LED，由于數目較多，照明(ming)效果很好(hao)。

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當鉛酸電池電(dian)(dian)壓為4V時(shi)，實測彩燈(deng)工作電(dian)(dian)流(liu)約60mA，高(gao)亮LED電(dian)(dian)流(liu)竟(jing)達600多mA。這(zhe)樣大的電(dian)(dian)流(liu)不(bu)(bu)僅使得每次(ci)充滿電(dian)(dian)后(hou)照明(ming)時(shi)間不(bu)(bu)會太(tai)長，而且會對電(dian)(dian)池內部結構造(zao)成損(sun)傷，縮(suo)短使用(yong)壽命，因(yin)此必須給高(gao)亮LED串入一個小阻值限流(liu)電(dian)(dian)阻，經多次(ci)試驗選定1.2Ω時(shi)工作電(dian)(dian)流(liu)最(zui)終(zhong)降為320mA，而亮度變化不(bu)(bu)太(tai)明(ming)顯，因(yin)該(gai)款燈(deng)改動不(bu)(bu)大，改造(zao)后(hou)的電(dian)(dian)路原理圖省略。

通過(guo)以上剖析發現，市場上出售(shou)的各(ge)種LED燈電(dian)路(lu)大多過(guo)于簡單，雖說價(jia)格十分便(bian)(bian)宜(yi)，但在客觀上仍會造成能源浪費(fei)，只有經過(guo)一(yi)番合理改進，才(cai)能既(ji)保(bao)留它經濟便(bian)(bian)攜的優點(dian)，又有效地(di)提高使用安全(quan)性和可(ke)靠性。