[Noisebridge-discuss] driving multiple LEDs with minimal batteries

Taylor Alexander tlalexander at gmail.com
Thu Jan 6 15:37:42 PST 2011


I've been to NB a few times, but its usually tough for me to get out there.
I also have a full CNC shop at work and I am in charge of it all, so I can
make pretty much anything here. :)

I do have a box of miscellaneous things that I want to bring up to NB. I do
like NB and would love to make it up there more!
-Taylor

On Thu, Jan 6, 2011 at 3:31 PM, jim <jim at systemateka.com> wrote:

>
> hey, taylor! i hope you show up at the NB space
> and toy around with the various electronic tools
> and supplies that are here.
>
>
>
> On Thu, 2011-01-06 at 13:00 -0800, Taylor Alexander wrote:
> > Hey. I just signed up for the mailing list (i've been on the useless
> > digest format for years, finally switched to the individual mails)
> > just to I could help here. First of all, am I responding right? Do I
> > just hit reply all? I'm new to the whole mailing list concept.
> >
> > As far as LEDs, I do plenty of PCB design in EAGLE and have been
> > playing with high current LED driver circuits lately. I just made a
> > board with 4 CREE XP-G LEDs that each are driven at about 800mA. The
> > whole board draws about 10w and puts out as much light as a 60w bulb!
> > Gets pretty hot too...
> >
> > I've recently set up my whole lab downstairs for SMT soldering, with a
> > nice microscope, hot air system, and all the bits and pieces I need
> > for soldering. Its pretty awesome!
> >
> > I haven't read all the e-mails in this thread as they were all mixed
> > in with the digest till i switched it over an hour ago, but what are
> > you trying to do? Drive some LEDs from a single battery i gather? I've
> > been meaning to do that to make a flashlight, actually.
> >
> > How many LEDs do you need to drive, and at what current level?
> >
> > Have you seen some of the DIY flashlight circuits available at
> > Dealextreme? http://www.dealextreme.com/details.dx/sku.25505
> >
> >
> > For circuit design, I use the calculator
> > on http://www.national.com/analog but it is focused on Lumen output.
> > Helpful though. You can also just look at their LED drivers section. I
> > found this chip with a quick search. Needs at least 3V but might be
> > helpful. Simple enough to use
> > too. http://www.national.com/pf/LM/LM3405.html#Overview
> >
> >
> > I've become pretty familiar with their drivers, and could pretty
> > easily lay out a board to help if you need it. Then you could get them
> > made at BatchPCB, and if you need help assembling, I may be able to
> > help at my place in the South Bay. I am normally really busy, but this
> > actually wouldn't take too much time, and I've been interested in
> > doing more open source LED boards. I actually recently registered
> > OpenSourceLighting.com, though I haven't done anything with it yet. I
> > want to combine 3D printing from Ponoko with boards from BatchPCB, and
> > create a little community to help people with designing LED lighting
> > solutions. Don't know if I'll ever take it off though.
> >
> >
> > -Taylor Alexander
> >
> >
> >
> >
> > On Thu, Jan 6, 2011 at 12:17 PM, meredith scheff <satiredun at gmail.com>
> > wrote:
> > > Thanks everyone!
> > > It's the booster that I was thinking of, i'm looking forward to
> > trying it.
> > > It's a big hurdle in wearable electronics.
> > > M
> > >
> > > On Thu, Jan 6, 2011 at 5:11 AM, Christoph Maier
> > > <cm.hardware.software.elsewhere at gmail.com> wrote:
> > >>
> > >> On Wed, 2011-01-05 at 21:30 -0800, T wrote:
> > >> > > Now, what's all this SEPIC stuff, anyways?
> > >> >
> > >> > SEPIC is a particular type DC-DC converter such as buck, boost,
> > >> > buck-boost, can cuk
> > >> >
> > >> > http://en.wikipedia.org/wiki/SEPIC
> > >>
> > >> SEPIC is what Dr. Foote calls a boost converter
> > >> http://en.wikipedia.org/wiki/Boost_converter
> > >> in last November's Five Minutes of Fame,
> > >> http://www.ustream.tv/recorded/10946425 ,
> > >> beginning at about 49 1/2 minutes.
> > >> (Can anyone, by any chance, post the slides somewhere,
> > >> Nudge nudge. Nudge nudge. Know what I mean?)
> > >>
> > >> Unlike the two-component solution
> > >> [ http://www.diodes.com/datasheets/ZXSC380.pdf
> > >> page 1, "Typical application circuit",
> > >> and page 6, "Application Notes", Fig. 2],
> > >> with a current regulation and efficiency that is so-so
> > >> [see the graphs on page 3],
> > >>
> > >> Jonathan draws some serious power,
> > >> so he needs a little more than 2 components,
> > >> probably even more than the 5 components in Fig. 5,
> > >> to control current and efficiency more accurately
> > >> than the ZXSC380, which is more optimized for blinkenlights
> > >> (well, ok, 200kHz blinkenlights,
> > >> so it looks continuous to the human eye)
> > >> running off a single 1.5V-ish battery.
> > >>
> > >> An LT3092 is the [Norton] equivalent of a waffle iron,
> > >> as presented in
> > >> http://www.ustream.tv/recorded/10946425 , 51:40 minutes.
> > >>
> > >> [ http://en.wikipedia.org/wiki/Emperor_Norton ,
> > >>  http://en.wikipedia.org/wiki/Norton_equivalent ]
> > >>
> > >>
> > >> HTH
> > >> Christoph
> > >> --
> > >> Linear current sources are easy,
> > >> [
> > >>
> >
> http://reference.kfupm.edu.sa/content/c/m/cmos_current_reference_without_resistanc_122569.pdf
> > >> ,
> > >>  http://www.eelab.usyd.edu.au/andre/publications/BiasgenAICSP.pdf ]
> > >>
> > >> getting sufficient control over the necessary means of production,
> > >> however ephemeral, is anything but.
> > >>
> > >>
> > >> _______________________________________________
> > >> Noisebridge-discuss mailing list
> > >> Noisebridge-discuss at lists.noisebridge.net
> > >> https://www.noisebridge.net/mailman/listinfo/noisebridge-discuss
> > >
> > >
> > >
> > > --
> > >
> > > Ladycartoonist.com
> > >
> > > ___________
> > >
> > > A human being should be able to change a diaper, plan an invasion,
> > butcher a
> > > hog, conn a ship, design a building, write a sonnet, balance
> > accounts, build
> > > a wall, set a bone, comfort the dying, take orders, give orders,
> > cooperate,
> > > act alone, solve equations, analyze a new problem, pitch manure,
> > program a
> > > computer, cook a tasty meal, fight efficiently, die gallantly.
> > > Specialization is for insects.
> > >
> > > -Robert A. Heinlein
> > >
> > > _______________________________________________
> > > Noisebridge-discuss mailing list
> > > Noisebridge-discuss at lists.noisebridge.net
> > > https://www.noisebridge.net/mailman/listinfo/noisebridge-discuss
> > >
> > >
> >
> >
> > _______________________________________________
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> > Noisebridge-discuss at lists.noisebridge.net
> > https://www.noisebridge.net/mailman/listinfo/noisebridge-discuss
>
>
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