[Hackupy-discuss] USB Chargers

[Akiba]

One thing to try  is possibly just keeping the same PCB and breaking out the
buck converter to a separate board with the same footprint as the device
from Akizuki. That way the original design can be used unmodified since it's
known good and the buck guts can be switched out based on what's
available/needed. I also think that it would be an interesting twist to
throw an AVR on the PCB and allow people to add features via the Arduino
environment. I'm pretty sure there will be some pretty wacky and useful
things added.        

 

Also, within THS, we're using the 12V charger as one of the devices in a
disaster management toolkit that we're trying to put together. It's a basket
of devices that are ready to go for the next disaster/crisis that will occur
somewhere. We've noticed that many crisis situations share the same
problems, mainly that access to infrastructure (power, comms, water, etc)
suddenly disappears. If we can make more progress on this, then hopefully
we'll try to turn it into a hackerspace-wide effort. It should be pretty
interesting and a lot of the discussions on stuff needed for hackupy are
giving us ideas on other devices to include. 

 

Enclosures are essential but I don't think they need to be too fancy. They
will probably need to be somewhat moisture proof but also have access to
open air in case its under full load. Most of those requirements would need
to come out from testing to see what the enclosure air flow needed would be.

 

Akiba

FreakLabs Open Source Wireless

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  _____  

From: miloh [mailto:froggytoad at gmail.com] 
Sent: Tuesday, December 06, 2011 2:40 AM
To: akiba at freaklabs.org
Cc: hackupy-discuss at lists.hackerspaces.org
Subject: Re: [Hackupy-discuss] USB Chargers

 

 

On Mon, Dec 5, 2011 at 4:55 AM, Akiba <akiba at freaklabs.org> wrote:

Sorry about the down time. Caught a nasty bout of bronchitis for the past
few weeks. 

Regarding chargers, we (Tokyo Hackerspace) can help acquire the DC/DC
converters from Akizuki. The schematic should also be modified so that the
particular DC/DC converter is replaced with something more readily available
say from Digikey or via a DC/DC switcher and some discrete parts. 

 

 

 

 

Just getting over a bad case of drywall throat myself.

 

Great, we will test these out and be in touch for more Akizuki's if we want
more!

 

Just as an exercise though, I'm curious about replacement parts for the
Akizuki buck.  I haven't looked for other replacements, but I think the
monolithic IC with a heat sink solution should be targeted around $3 to
match the Akizuki. Is this unreasonable here?  Any way to get the price to
$3 for small orders the a 20W-30W buck + heat sink? Linear has nice
parametric product finders
<http://www.linear.com/products/step-down_(buck)_regulators>
http://www.linear.com/products/step-down_(buck)_regulators  Maybe this board
as is could be used with breakout boards for parts easily sourced in
different areas of the world.

 

USB charge currents will go higher than 1A for some devices, right? I know
other folks are more up-to-date on the issue of typical charge currents for
usb connected devices, but with 4 ports available on the board, perhaps we
should look for something with a 4A or greater supply capability.  

 

What can we do to further differentiate this from existing COTS hardware?
Being kit based is great in of itself, it gives folks something to spend
some time learning about. Having options for easily sourced cases (abs or
pvc pipe),  or unique and personalized case (laser cut custom
hacupyEnclosures ) is good also. Maybe the road heads towards changing the
pcb design in subsequent versions to include atypical features like a
uc+piezo alarm, exposed pcb for alligator clip jumpers, or more... 

 

-rma 

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