No subject

- Maintain supply voltage somewhere between 5V and 25V.  DC
- Be able to supply upwards of 15 Watts of power.
- Not melt down under current loads up to 3 amps.
- The positive polarity goes to the center pin.  Presumably also the
coaxial core. "Shield Ground" in audio/telco language.

Architecturally, the AC adapter (or the hand crank, Yoyo, solar panel,
bovine generator, etc) is a  seperate subsystems from the XO. You have
to get the public interfaces correct, but the private implementation
details need only be effective.

Trying to build one from DigiKey parts is a good learning exercise,
but probably not the best way to approach this. If I were doing this,
here's how I'd go about it:

- Find a suitable, readily available mated connector set which can
handle 30 volts, and 3 amps.  Get several sets.
- Cut your XO AC adapter power cort and put a mated pair of connectors inline.
- find another similar DC adapter, snip the core, and add on one of
your connector mates.

Now you have two AC adapters you can use, in case one breaks.

- Add a connector to a 12V cigarrette  lighter car adapter, observing
polarity, and now you have a car adapter, too.
- Use the same technique for a hand crank (if you can find one) solar
panel (or gang of solar panels, if you need more power capacity.

- DO NOT run AC power mains (120V) directly into your XO. This will
destroy the XO.

- Once you have that working, you can focus on building a more generic
power supply with all the bells and whistles (like a replacable fuse,
etc.)

Once I get XO hardware and can spend some times understanding and
testing solutions, I'll write-up a page for the wiki discussing other
similar ideas.

-- 
Steve Holton
sph0lt0n at gmail.com


On Jan 15, 2008 5:05 PM, jim stockford <jim at well.com> wrote:
>
>
>     anybody able to specify the parts needed to make
> a replacement? i'm guessing something like:
> * transformer
> * diode bridge
> * two-conductor cable
> * connector
> * other?
> (the above list is insufficient because it doesn't spec
> the transformer, diode bridge, and cable, needs
> something like Xformer:10:1 stepdown 2A secondary;
> diode bridge 3A at 50 VDC; two-conductor cable #22
> stranded...; connector must be wired positive exterior
> negative interior; necessary disclaimer: "if you do this,
> you're nuts and you void any warrantees".)

-- 
Steve Holton
sph0lt0n at gmail.com