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Article #269Re: Best way to power array of LEDs?
From: Ban
Date: Fri, 04 Oct 2002 06:47
Date: Fri, 04 Oct 2002 06:47
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2720 bytes
"Jerry G." <jerryg50@hotmail.com> schrieb im Newsbeitrag news:Rsan9.14070$qh1.1622310@news.ca.inter.net... > Each LED must have its own series resistor. Most of these LED's work > at about 30 to 40 ma with about 1.6 VDC across them. You should be able > to use a 320 ohm 1/2 watt resistor in series with each LED if these are > in the spec range that I used as an example. > > LED's cannot be wired in parallel to each other being fed from one > resistor. They can not also be wired in series with each other. > Nope, of cause they can be wired in series if the available voltage allows it. Check the datasheet for the typical forward voltage. Red leds have around 1.7V, yellow/green ones are 1.9-2.3V, blue/white ones even higher 3.2-3.8V. If you use just a resistor in series with each chain, you should calculate it for the max. supply voltage which I would suggest is 14.0V. Now if you put 6 red leds in series with 20mA current rating, you get 6*1.7V=10.2V; 14V-10.2V= 3.8V; 3.8V/20mA=190 ohms; take 180 or 200 ohms. The resistor can be a normal 1/4W 0207 type. -- ciao Ban electronic hardware designer http://thinkamove.com/
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X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 112d1e,4ef4c9d4aea85e1f X-Google-Attributes: gid112d1e,public X-Google-Thread: 103407,4ef4c9d4aea85e1f X-Google-Attributes: gid103407,public X-Google-Thread: 10d137,4ef4c9d4aea85e1f X-Google-Attributes: gid10d137,public X-Google-Thread: 1131b0,4ef4c9d4aea85e1f X-Google-Attributes: gid1131b0,public X-Google-Thread: 1118be,4ef4c9d4aea85e1f X-Google-Attributes: gid1118be,public X-Google-ArrivalTime: 2002-10-03 23:47:27 PST Path: arc1-ca.pugleaf.net!archiver1.google.com!news1.google.com!newsfeed.stanford.edu!news.tele.dk!small.news.tele.dk!194.25.134.62!newsfeed00.sul.t-online.de!newsfeed01.sul.t-online.de!t-online.de!nntp.infostrada.it!news-out.tin.it!news-in.tin.it!news2.tin.it.POSTED!not-for-mail From: "Ban" <bansuri@masterweb.it> Newsgroups: sci.electronics.components,sci.electronics.design,alt.engineering.electrical,aus.electronics,sci.electronics.repair References: <0001HW.B9C26E7400A7161B165FEAC0@news.covad.net> <Rsan9.14070$qh1.1622310@news.ca.inter.net> Subject: Re: Best way to power array of LEDs? Lines: 28 X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Message-ID: <2Qan9.3129$cS4.107732@news2.tin.it> Date: Fri, 04 Oct 2002 06:47:26 GMT NNTP-Posting-Host: 80.116.46.227 X-Complaints-To: newsmaster@tin.it X-Trace: news2.tin.it 1033714046 80.116.46.227 (Fri, 04 Oct 2002 08:47:26 MET DST) NNTP-Posting-Date: Fri, 04 Oct 2002 08:47:26 MET DST Organization: TIN