[Noisebridge-discuss] driving multiple LEDs with minimal batteries

Christoph Maier cm.hardware.software.elsewhere at gmail.com
Tue Jan 4 20:21:55 PST 2011


On Tue, Jan 4, 2011 at 12:06 PM, meredith scheff <satiredun at gmail.com> wrote:
> I'd like to do a soft circuit scarf or three, but I'm always running up
> against the problem of power. I usually use fairly low power LEDs
> (<2v) driven by a 9v battery or one of sparkfun's LiPos.
> I've heard tell of somehow being able to power more, but I'm still learning
> this EE stuff. Could some kind person point me in the right direction?
> Meredith
>
> --
>
> Ladycartoonist.com

A MESSAGE FROM THE DEPARTMENT OF OVERENGINEERING

I''m sitting here in the lab of a fellow (of the IEEE),
[ http://pony.noisebridge.net/~cmaier/wearables/lab_with_stuff.jpg ]
trying to make contributions to biomedical instrumentation,
but I'm always running up against the problem of making circuits
actually comfortably wearable.
We usually end up using little PCBs (< quarter sized) and copper wires
or ribbon cables.
I've heard tell of some folks who make costumes that blink with sound,
or dresses that point north,
but I have no clue about this tailoring stuff.
Could someone match me up with a talented seamstress?
[For all you Terry Pratchett fans: Not THAT kind of seamstress!]

> ___________
>
> 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

Add "design a full custom CMOS biosensor IC" to that list.
The little square insect in the middle of the green PCB to the left in
http://pony.noisebridge.net/~cmaier/wearables/hackerspace_meets_academia.jpg
kept me busy enough over the last week that I missed 27C3
(well, at least I didn't end up in an apartment JotWeDe in Berlin with
Leif this end of year).

For electronics that's actually wearable,
I'm kind of looking for an excuse to try to build some reasonably
standard circuit,
e.g., one with an LTC4060 [ http://cds.linear.com/docs/Datasheet/4060f.pdf ]
on some PCB material that is more comfortable to wear than a rigid PCB.
This kind of stuff:
http://ladycartoonist.com/2010/05/soft-circuit-kits-now-for-sale-2/
looks promising,
but I'd need to find a way to find out the design constraints
(minimum trace width, pitch, etc.) and feed them into an EDA program
(default choice at the moment is Altium, for what it's worth),
and have someone either do the sewing or teach me how not to mutilate
myself with a sewing machine and/or serger.

Eventually, some of these DIY microchips:
http://www.facebook.com/photo.php?pid=31969144&l=6b994e53e9&id=1369525119
should end up in a wearable, dare I think washable, garment.

But for starters, a wearable charger for one of these slivery things
on the lab bench,
or an antiseptic SEPIC
[ http://www.diodes.com/datasheets/ZXSC380.pdf or some such ]
seems a good project.

Christoph,
playing postdoc @UCSD
looking for a valid excuse for one of my quarterly noisebridge visits.


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