[Noisebridge-discuss] driving multiple LEDs with minimal batteries

[Jonathan Foote]

A likely problem is the dropping resistors which waste power. Also 9V
batteries are not great for power density.

Several solutions: as was mentioned, a coin cell battery will happily
drive one or two LEDs for a good long time.

Another approach is to use a "Joule Thief" circuit and a single AA. JFGI.

In the overengineering department, a LiPo battery (of which there are
boxes full at NB) plus a constant current SEPIC driver would be most
efficient, and rechargeable to boot.

Or just use the LiPo with dropping resistors; SparkFun sells a
charging circuit chip + breakout board so you can recharge it from a
USB port. No wasted batteries!


-J


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
>
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