Article View: sci.electronics.components
Article #138Re: Best way to power array of LEDs?
From: Tony Williams
Date: Fri, 08 Nov 2002 08:24
Date: Fri, 08 Nov 2002 08:24
21 lines
2699 bytes
2699 bytes
In article <aqeils04r3@drn.newsguy.com>, Winfield Hill <whill@picovolt.com> wrote: > Hmm, it's light-level stabilized now, I suppose there could > be a mode switch for current mode. Hmm, you don't think the > LM385 is sufficiently stable (it must be better than 0.1%)? It has the wrong sort of stability. As well as the temperature-dependance of the light output from LEDs there is also the problem of ambient light..... it would be nice to have a constant contrast. Perhaps you should compare the outputs from two photocells, one looking at ambient light and the other looking at a LED which is driven to maintain constant contrast. The current in that LED is used as the reference current for all the others. That deals with the two probs in one swipe. -- Tony Williams.
Technical Details
Message-ID:
<4b92130962tonyw@ledelec.demon.co.uk>Path:
arc1-ca.pugleaf.net!archiver1.google.com!news1.google.com!newsfeed.stanford.edu!bloom-beacon.mit.edu!news-out.cwix.com!newsfeed.cwix.com!newsfeed.icl.net!newsfeed.fjserv.net!colt.net!kibo.news.demon.net!news.demon.co.uk!demon!ledelec.demon.co.uk!tonywReferences:
<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> <KVdHjAAjM3w9Ew8l@jmwa.demon.co.uk> <aq17gb$7ut$1@reader1.panix.com> <aq1ckv02qbk@drn.newsguy.com> <3DC6F8DC.CF94292A@bellatlantic.net> <aq7f2c01co0@drn.newsguy.com> <3DC93ECF.77E10699@clifto.com> <aqdlqr01vcm@drn.newsguy.com> <khelsu0c6n1hjgpmovcta6i02178jfhit3@4ax.com> <aqeils04r3@drn.newsguy.com>Show Full Headers
Complete Article Headers
X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 112d1e,4ef4c9d4aea85e1f X-Google-Attributes: gid112d1e,public X-Google-Thread: 1131b0,4ef4c9d4aea85e1f X-Google-Attributes: gid1131b0,public X-Google-Thread: 10d137,4ef4c9d4aea85e1f X-Google-Attributes: gid10d137,public X-Google-Thread: 1118be,4ef4c9d4aea85e1f X-Google-Attributes: gid1118be,public X-Google-Thread: 103407,4ef4c9d4aea85e1f X-Google-Attributes: gid103407,public X-Google-ArrivalTime: 2002-11-08 00:28:25 PST Path: arc1-ca.pugleaf.net!archiver1.google.com!news1.google.com!newsfeed.stanford.edu!bloom-beacon.mit.edu!news-out.cwix.com!newsfeed.cwix.com!newsfeed.icl.net!newsfeed.fjserv.net!colt.net!kibo.news.demon.net!news.demon.co.uk!demon!ledelec.demon.co.uk!tonyw From: Tony Williams <tonyw@ledelec.demon.co.uk> Newsgroups: sci.electronics.components,sci.electronics.design,alt.engineering.electrical,aus.electronics,sci.electronics.repair Subject: Re: Best way to power array of LEDs? Date: Fri, 08 Nov 2002 08:24:46 +0000 (GMT) Organization: None Lines: 21 Message-ID: <4b92130962tonyw@ledelec.demon.co.uk> References: <0001HW.B9C26E7400A7161B165FEAC0@news.covad.net> <Rsan9.14070$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> <KVdHjAAjM3w9Ew8l@jmwa.demon.co.uk> <aq17gb$7ut$1@reader1.panix.com> <aq1ckv02qbk@drn.newsguy.com> <3DC6F8DC.CF94292A@bellatlantic.net> <aq7f2c01co0@drn.newsguy.com> <3DC93ECF.77E10699@clifto.com> <aqdlqr01vcm@drn.newsguy.com> <khelsu0c6n1hjgpmovcta6i02178jfhit3@4ax.com> <aqeils04r3@drn.newsguy.com> NNTP-Posting-Host: ledelec.demon.co.uk X-Trace: news.demon.co.uk 1036744104 14421 194.222.56.201 (8 Nov 2002 08:28:24 GMT) X-Complaints-To: abuse@demon.net NNTP-Posting-Date: Fri, 8 Nov 2002 08:28:24 +0000 (UTC) User-Agent: Pluto/1.14i (RISC-OS/3.60)