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)閃爍燈.提(ti)醒聽力不太(tai)好的(de)(de)老年人(ren)及時(shi)接電(dian)(dian)(dian)(dian)話(hua)(hua)(hua),因電(dian)(dian)(dian)(dian)話(hua)(hua)(hua)摘機后(hou)(hou)LED燈會(hui)熄(xi)滅,還(huan)能(neng)幫你及時(shi)發現電(dian)(dian)(dian)(dian)話(hua)(hua)(hua)是(shi)(shi)否(fou)被他人(ren)盜打(da),同時(shi)也具有一(yi)定的(de)(de)防雷擊保護(hu)作用。不過(guo)由于(yu)該產(chan)品(pin)使用的(de)(de)是(shi)(shi)電(dian)(dian)(dian)(dian)話(hua)(hua)(hua)所屬的(de)(de)電(dian)(dian)(dian)(dian)信機房饋電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)源,使用時(shi)一(yi)旦索取電(dian)(dian)(dian)(dian)流(liu)過(guo)大難免(mian)會(hui)影響(xiang)電(dian)(dian)(dian)(dian)話(hua)(hua)(hua)撥打(da)和傳(chuan)真收發,特別是(shi)(shi)ADSL寬(kuan)帶(dai)用戶撥號上(shang)(shang)網(wang)時(shi)容易造成頻(pin)繁掉線。圖3是(shi)(shi)電(dian)(dian)(dian)(dian)話(hua)(hua)(hua)線LED燈電(dian)(dian)(dian)(dian)路工作原理圖,36V或48V的(de)(de)電(dian)(dian)(dian)(dian)話(hua)(hua)(hua)線路直流(liu)電(dian)(dian)(dian)(dian)壓經10kΩ限流(liu)電(dian)(dian)(dian)(dian)阻并由4個二極管(或整(zheng)流(liu)橋)作極性變換后(hou)(hou)加(jia)在LED上(shang)(shang),當(dang)電(dian)(dian)(dian)(dian)話(hua)(hua)(hua)饋電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)壓為(wei)36V時(shi),實測工作電(dian)(dian)(dian)(dian)流(liu)約1.2mA,亮度偏(pian)低,把限流(liu)電(dian)(dian)(dian)(dian)阻換成5.6kΩ時(shi)工作電(dian)(dian)(dian)(dian)流(liu)升為(wei)2.1mA:亮度稍微有些增加(jia)。
考慮到電話線LED燈對上網存在不利影響(xiang),不能經常接在電(dian)話(hua)線(xian)上,筆者(zhe)又對該燈(deng)進行(xing)了一(yi)番(fan)改造,改造后的(de)電(dian)路原理圖(tu)如圖(tu)4所示,把(ba)中間的(de)6顆(ke)LED改成并聯,同時(shi)增加(jia)一(yi)塊3.6V的(de)手機鋰(li)離(li)子(zi)電(dian)池(chi),平(ping)時(shi)使用(yong)內置的(de)新增鋰(li)電(dian)工(gong)作,當限流電(dian)阻(zu)為5.6Ω時(shi),工(gong)作電(dian)流約(yue)(yue)120mA,亮度比較令人滿意。緊急情(qing)況下(xia)仍可(ke)采(cai)用(yong)插入電(dian)話(hua)分機接口照明(ming),改造后的(de)工(gong)作電(dian)流約(yue)(yue)4.6mA,亮度還(huan)算說得過去(qu)。
自帶鉛酸蓄電池能充電的LED燈:
根據實物畫出的(de)電(dian)路工作原(yuan)理圖(tu)(tu)如圖(tu)(tu)5所示,220V交流市電(dian)經電(dian)容降(jiang)壓、二極管整流后(hou)給鉛酸蓄(xu)電(dian)池充(chong)電(dian),紅色(se)LED作充(chong)電(dian)指示。充(chong)好電(dian)后(hou)使(shi)用時閉合按(an)鈕(niu)開關(guan)K,將首(shou)先(xian)接(jie)通(tong)3顆(ke)彩色(se)閃爍(shuo)LED,發(fa)出夢幻般變(bian)化莫(mo)測的(de)七彩光芒(mang),在夜間(jian)平(ping)添一(yi)些生活(huo)樂(le)趣,再按(an)一(yi)下開關(guan)K則關(guan)閉彩色(se)閃爍(shuo)LED,接(jie)著再按(an)才會(hui)接(jie)通(tong)24顆(ke)并聯(lian)的(de)高亮LED,由于(yu)數目較多(duo),照明效果很(hen)好。
當鉛酸電池電(dian)壓為4V時,實(shi)測彩燈(deng)工作電(dian)流(liu)約60mA,高亮(liang)LED電(dian)流(liu)竟達600多(duo)mA。這(zhe)樣大(da)(da)的電(dian)流(liu)不(bu)僅使得每次充滿(man)電(dian)后照明時間不(bu)會(hui)太(tai)長(chang),而且會(hui)對電(dian)池內(nei)部結構造(zao)(zao)成損傷,縮短使用壽命,因此必須給(gei)高亮(liang)LED串入一個小阻(zu)值限流(liu)電(dian)阻(zu),經(jing)多(duo)次試(shi)驗選定1.2Ω時工作電(dian)流(liu)最終降(jiang)為320mA,而亮(liang)度變化不(bu)太(tai)明顯(xian),因該(gai)款燈(deng)改動(dong)不(bu)大(da)(da),改造(zao)(zao)后的電(dian)路原(yuan)理圖省略。
通(tong)過以上剖析發現,市場上出售的各種LED燈電路大多過于簡單,雖(sui)說價(jia)格十分便宜,但(dan)在客觀上仍會造成能源浪費(fei),只有(you)經過一番合(he)理改進(jin),才能既保留它經濟便攜的優(you)點,又(you)有(you)效地提(ti)高使用(yong)安(an)全性和可靠性。