Re: Best way to power array of LEDs?

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#284

From: John Woodgate
Date: Fri, 04 Oct 2002 13:03

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I read in sci.electronics.design that Keith Wootten
<keith.w@ntlworld.com> wrote (in <P0HAA5Jd3Un9EwWS@ntlworld.com>) about
'Best way to power array of LEDs?', on Fri, 4 Oct 2002:

>You can mitigate this to a useful extent by using a small filament bulb 
>instead of a resistor.  The positive temperature coefficient of the bulb 
>will help to keep the current variation reasonable as the supply voltage 
>changes.  The bulb should be selected to run at more or less normal 
>brightness at maximum supply voltage while passing maximum LED current.

A good idea IF you can find a suitable lamp. The lowest current lamps
readily available in UK (excluding 28 V ones) are 6 V 40 mA. You *could*
use one in series with two parallel strings of three LEDs. 
-- 
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk 
Interested in professional sound reinforcement and distribution? Then go to 
http://www.isce.org.uk
PLEASE do NOT copy news posts to me by E-MAIL!

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From: John Woodgate <jmw@jmwa.demon.contraspam.yuk>
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: Fri, 4 Oct 2002 14:03:57 +0100
Organization: JMWA Electronics Consultancy
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