Electrical hacking (was Re: [Techtalk] [OT] charging USB device without a PC)

Conor Daly conor.daly at oceanfree.net
Sun Apr 13 09:54:21 EST 2003

On Sat, Apr 12, 2003 at 11:15:30PM -0400 or so it is rumoured hereabouts, 
Brenda Bell thought:
> Quoting Conor Daly <conor.daly at oceanfree.net>:
> > OK, did that.  USB socket off an old mobo, power socket off an old 
> > receiver.  It's now hooked up to the charger with the charging light on.
> > 
> > <runs off to check> Yup, charging complete, battery not even warm... 
> > I'll
> > have to run the battery flat and test properly.
> I'm impressed.  But then again, I'm a electrical wimp (would have probably
> bought a powered USB hub :)

It's not that hard.  It _is_ important to know what you _can_ safely[0] or
usefully[1] mess with and what you _just don't touch_.  

Things you just don't touch:

o High voltage stuff inside your sick monitor (see [0]).
o The wiring in gadgets in your bathroom (see [0] also).
o The silk screened flexible printed circuit in your ergonomic keyboard
  (see ! [1]).
o The extremly fine printed circuits on your mobo (see [1]).

Things I have successfully fixed:

o A monitor where the video socket had broken some of its connections to
  its main board.  This involved tracing the circuit from each pin to the
  next solder joint on the board and soldering in a wire between the two.
  This required only patience, a magnifier and a little practice with a
  soldering iron.

o The central locking module in the car.  This was a case of decaying
  solder joints again but only required each joint to be resoldered.

o Modification of my (cheapo) toy car racing set to run off a transformer
  as well as batteries.  

Things I have fixed after I broke them in the first place:

o The wiring in the wall of the house after I drove a screw right through
  it thus shorting out the whole house.

o The aforementioned printed circuit in the keyboard which I regularly
  need to patch with conductive paint (Good tip actually, The "silver"
  paint for repairing windscreen demisters sold in automotive shops is
  just the thing for silk screened printed circuits).

Of course, the other thing to remember is the cost efficiency.  How much
is your time worth?  Will you spend more time fiddling around than you
would spend in cash on the ready made device.  Incidentally, there's an
in-car USB charger available for $15 (google for usb treo charger) if you
do have a need for PC-less USB charging...

Conor (who does this stuff for fun)

[0] Without killing yourself or your family.
[1] likely to be successful.
Conor Daly <conor.daly at oceanfree.net>

Domestic Sysadmin :-)
  9:26am  up 23 days, 15:02,  0 users,  load average: 0.00, 0.00, 0.00
  9:26am  up 23 days, 15:01,  1 user,  load average: 0.24, 0.12, 0.08

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