[Noisebridge-discuss] LED scarf with*out* batteries [driving multiple LEDs with minimal batteries]
T
t at of.net
Mon Jan 17 19:14:16 UTC 2011
...
>> The OP was looking for a simple way to add lights to a scarf, IIRC,
>> and didn't have much electronics experience and some trepidation at
>> building anything complex. I fear we have driven her away. Or
>> perhaps I misjudge...
>
> Which solution did you end up going with, Meredith?
Yes, tell us.
> Power supplies being what they are, it occurs to me that it would be a
> good idea to have a poster near the components showing the fundamental
> linear power supply types and the simpler switching ones. I'll draw
> one up. ...
Thank you for that.
> It would also be nice to put the typical conversion efficiencies next
> to each power supply type to help the reader select an appropriate
> circuit, but a quick look through my handbooks doesn't give me any
> useful data.
Hmmm. I recall an online DC-DC switch-mode design thing where you
could get efficiencies calculated... IIRC the values of the inductors
and capacitors and the switching frequency made a big difference.
Hey, just found this. Looks like you can power a circuit from a
thermal gradient!
On the kind of night where you'd need a scarf you could have the
required 5 degree C (K) gradient between your body and the air...
Part 1:
http://new.eetimes.com/design/power-management-design/4211949/Ultralow-voltage-energy-harvester-powers-wireless-sensors-from-waste-heat--Part-1-of-2-?Ecosystem=power-management-design
Part 2:
http://new.eetimes.com/design/power-management-design/4211950/Ultralow-voltage-energy-harvester-powers-wireless-sensors-from-waste-heat--Part-2-of-2-?Ecosystem=power-management-design
Best Regards.
T
Best Regards.
This is unedited.
P-)
...
>> The OP was looking for a simple way to add lights to a scarf, IIRC,
>> and didn't have much electronics experience and some trepidation at
>> building anything complex. I fear we have driven her away. Or
>> perhaps I misjudge...
>
> Which solution did you end up going with, Meredith?
>
> Power supplies being what they are, it occurs to me that it would be a
> good idea to have a poster near the components showing the fundamental
> linear power supply types and the simpler switching ones. I'll draw
> one up. If anyone has spare switching ICs they'd like to donate, let
> me know before Friday and I'll add them to the poster.
>
> It would also be nice to put the typical conversion efficiencies next
> to each power supply type to help the reader select an appropriate
> circuit, but a quick look through my handbooks doesn't give me any
> useful data. Is there a good reference that takes into account modern
> battery chemistries?
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