[Noisebridge-discuss] LED scarf *with* batteries [LED scarf with*out* batteries [driving multiple LEDs with minimal batteries]]

Taylor Alexander tlalexander at gmail.com
Mon Jan 17 13:39:25 PST 2011


Well I asked a while back what requirements the OP had, and I don't
think I ever saw any. So that was just one suggestion. You can bump
1.5v up to 12v or higher but I think efficiency goes down the farther
you go from the source voltage (i may be wrong on that), so lower
voltage in parallel might not be all that bad. Though I agree that
wiring is a pain.

And I guess I didn't realize the subject changed. Really it just
seemed like the OP never really got their answer. Someone else was
concerned the OP has been "scared away", so I just wanted to see if
there was anything else helpful to say on that.

I still maintain that designing the "proper" circuit is pretty simple.
National.com has a great LED array circuit calculator on their
website.
-Taylor




On Mon, Jan 17, 2011 at 1:19 PM, T <t at of.net> wrote:
> On Mon, Jan 17, 2011 at 12:41, Taylor Alexander <tlalexander at gmail.com> wrote:
>> It really sounded like the OP wanted to "build", not "learn", so
>> something pre-made is probably best.
>
> Uh, sure, but that doesn't keep me from having ideas that go beyond
> original intent (and of course I change the subject line to make that
> clear...)
>
>> I mentioned before, you can get extremely cheap booster circuits
>> designed for DIY-flashlight people, for ~$2 from dealextreme.
>>
>> Here is one: http://www.dealextreme.com/details.dx/sku.25505
>> Specs are a little unclear, but comments say
>> 3.2v 650ma output, and that it works with a single battery input.
>
> = 2.08 watts.  Cool.
>
> OK, cool, I guess you could drive a bunch of little LEDs from that.
> In parallel.
>
> Are there any complications from driving a bunch of little LEDs in parallel?
>
> Off the top of my head...
>
> - more wiring
>
> - a current-limiter or resistor per LED
>
> With a 12-19V you can run a chain of LEDs like xmas lights.  And only
> have to limit current once per chain.
>
> Tony
>


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