Longer XO transformer power cord in the plans?

John Watlington wad at laptop.org
Sun May 31 00:23:37 EDT 2009

We are considering changing from a "wall wart"
design to an "inline design", for the following reasons:

A - The difficulty in supporting "new" countries, when each
new plug design requires new tooling.   With an inline
design, only the plug at the end of the AC cable has to

B - The "wall wart" design limits the weight of the adapter.

C - A blow to the adapter when it is plugged in frequently
snaps the pins off of the wall wart.   I've seen a number
of "repaired" units that make me worry for the kids safety.

D - It can be difficult to find power strips with the right plug
orientation to accept multiple adapters of our current design.

Right now, we have a 1.5m cable on the wall wart.
I'm thnking about specifying a 0.8m  (outlet to floor) AC cable
and a 1.2m (floor to table) DC cable.   Shorter would be
cheaper, but might result in "dangling" adapters, something to
be avoided.

Quozl's comments are valid.   Not every child needs a
longer cable, and the cabling is a significant part of the cost
of the adapter.

I am still getting quotes to see how this change might
impact the adapter cost, and getting the industrial designers
to think about it.

Comments ?  Suggestions ?

On May 30, 2009, at 9:39 PM, James Cameron wrote:

> I know of no such plans, but the physics of the configuration has a
> bearing ...
> 1.  a longer cable has a larger voltage drop, and so a greater  
> amount of
> power is lost as heat, leading to greater inefficiency of power use,
> 2.  compensating for the voltage drop can only be done by either  
> raising
> the design voltage on the cable, or increasing the cross sectional  
> area
> of the copper,
> 3.  raising the design voltage is an unattractive option, since it  
> would
> expose the user to greater risk,
> 4.  increasing the cross sectional area would make the cable much
> heavier, and a substantially higher cost, which would vary  
> according to
> metal prices,
> 5.  increasing the length may also increase the trip hazard, and so
> further reinforcement of the sheath and restraint points may be
> required,
> 6.  not every child will need an extra two metres.
> Can you balance this against against the cost of properly placed
> domestic 110V or 240V outlets?
> -- 
> James Cameron    mailto:quozl at us.netrek.org     http:// 
> quozl.netrek.org/
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