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Article #181Re: Best way to power array of LEDs?
From: Sofie
Date: Sat, 02 Nov 2002 15:51
Date: Sat, 02 Nov 2002 15:51
36 lines
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3092 bytes
R. Lewis: I know I will get shot down here...... but here is a very inexpensive, SIMPLE and RELIABLE scheme: Depending on the specifications of the LEDs and how hard you want to drive them, you can adjust the value of the series dropping resistor. For example.....In series with each LED, a 680 ohm half watt resistor will limit the current to each LED to roughly 19 ma.... actually the total current swing of about 17 ma to 21 ma (a swing of only + or - 10% total) over the nominal automotive voltage operating range, driving, idling, and the motor not running. At a total of 36 LEDs, that is a TOTAL current draw of only 0.75 Amps..... LESS than a side marker or dome lamp..... so WHO CARES about "wasted power" in the dropping resistors. So, how complicated is this?....... 36 LEDs and 36 resistors..... not much to go wrong here. At that rate, you could hook up 100 LEDs and pull about 2 Amps..... roughly the same amount as a brake or tail-light...... and the heat and wasted power from the resistors will still be negligible..... and would not affect your gas mileage..... or I suppose a single drop of gasoline in several tank-fulls should take care of the extra power used. -- Best Regards, Daniel Sofie Electronics Supply & Repair - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - "R. Lewis" <h.lewis@connect-2.co.uk> wrote in message news:aq0h2t$nv1$1@thorium.cix.co.uk... > Amid all the jollity has anyone come up with an economical yet reliable way > of making a 36 led array with anywhere near a standard (constant) > specification? > > > >
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X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 112d1e,4ef4c9d4aea85e1f X-Google-Attributes: gid112d1e,public X-Google-Thread: 103407,4ef4c9d4aea85e1f X-Google-Attributes: gid103407,public X-Google-Thread: 1118be,4ef4c9d4aea85e1f X-Google-Attributes: gid1118be,public X-Google-Thread: 10d137,4ef4c9d4aea85e1f X-Google-Attributes: gid10d137,public X-Google-Thread: 1131b0,4ef4c9d4aea85e1f X-Google-Attributes: gid1131b0,public X-Google-ArrivalTime: 2002-11-02 07:52:41 PST Path: arc1-ca.pugleaf.net!archiver1.google.com!news1.google.com!newsfeed.stanford.edu!sn-xit-05!sn-xit-06!sn-post-01!supernews.com!corp.supernews.com!not-for-mail From: "Sofie" <sofie@olypen.com> Newsgroups: sci.electronics.components,sci.electronics.design,alt.engineering.electrical,aus.electronics,sci.electronics.repair Subject: Re: Best way to power array of LEDs? Date: Sat, 2 Nov 2002 07:51:20 -0800 Organization: Posted via Supernews, http://www.supernews.com Message-ID: <us7t1tk9t9t795@corp.supernews.com> References: <0001HW.B9C26E7400A7161B165FEAC0@news.covad.net> <Rsan9.14070$qh1.1622310@news.ca.inter.net> <ank9ep$lumv$1@hades.csu.net> <anku2n$5so$1@news.wave.co.nz> <7tGLdeAS6fn9EwBv@jmwa.demon.co.uk> <apvlvu$n2c$1@reader1.panix.com> <aq0h2t$nv1$1@thorium.cix.co.uk> X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 6.00.2600.0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 X-Complaints-To: abuse@supernews.com Lines: 38