[olpc-help] External DC Power Jack Specs

[Richard A. Smith]

Steve Holton wrote:

> A full technical description with tolerances in not available. The
> best I can do is reference the de-facto standard Richard gave us:
> Digikey part # CP-2195-ND
> When I get hardware in hand, I'll seek out the original manufacturer
> of the part. I'm sure they have a story to tell.

Let me save you the trouble.

http://dev.laptop.org/~rsmith/DCJACK.pdf

> We should probably include in here something about the coaxial cable
> they're using for power, if that was selected for physical
> characteristics. Many questions here. Again, I'll know more when I see
> one for myself.

Selected to match the design of the laptop.

> The Electrical Characteristics
>>From the Wiki pages (me hopes they are correct and up to date) you'll
> need a source which is/can:
> 
> - Maintain supply voltage somewhere between 5V and 25V.  DC

Hmm... Thats a bit off.  11V is about lowest you can go and still have
the XO run.

> - Be able to supply upwards of 15 Watts of power.
> - Not melt down under current loads up to 3 amps.

12V 1.5 amps is full load. so 18W.

> 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:

If you want to make a 12V supply as a constructionist learning exercise
then there are tons of web pages describing a variety of methods.  All
budding EE's should try to build at least 1 12V power supply. Please use
the proper cautions.  120V AC is lethal when mishandled.

If however, you just want a 12V supply that works then you can do much
better by searching for a surplus site thats selling 12V supplies and
either find one with a connector that works or hack off the connector
and add one that will. Highly likely it will be cheaper, better, and
safer than trying to roll your own.

-- 
Richard Smith  <richard at laptop.org>
One Laptop Per Child