[Gta04-owner] Solar charger - was How could GTA04 shine

[Alexander Lehner]

On Thu, 15 Mar 2012, Radek Polak wrote:
> You might be interested in this video:
>
> 	http://www.youtube.com/watch?v=EbL3-1vB73c
>

Yes, I know these guys. Pixel Qi is a spin off from the One Laptop Per 
Child project, and they have developed a special display and other 
hardware components with ultra-low power consumption.
For example, the WiFi chip can to mesh-networking without the CPU powered 
on, and the display - similair to ebook readers - doesn't need power at 
all to keep its image (at least in b/w-mode).

The idea with the charging crank, by the way, is also from them ;)
I own such a OLPC and it's really an amazing toy.
But I guess we are far away from this level of power reduction, since 
the display of the FR actually needs 1/3 of battery power.

To answer the other emails:

- Putting a simple diode between solar and battery will need a certin 
threshold voltage of about 0.3-0.7 volt, so not suitable to fully charge 
the batteries.

- I'll give the LTC3105 a try, thanks for the tip. I've been already 
playing with DC/DC converters; biggest problem is the amount of additional 
big eletronic parts like discrete L/C/R's. If you don't own a SMD assembly 
line, you end up with the same problem that the production of the GTA04 
has...

Picture:

http://wiki.openmoko.org/wiki/Image:Dcdc_converter.jpg


A.