On Oct 22, 10:35*am, "Dave Plowman (News)"
wrote:
In article ,
* *Jules Richardson wrote:









On Fri, 21 Oct 2011 23:55:44 +0100, Dave Plowman (News) wrote:
I've upgraded to a much larger screen one which is also nice and slim..
But the power connector is a small USB one. Could I do something like
the same with that, but obviously using an easier to fit connector than
the USB one?
Going from memory here...
For most little USB charger/device combinations, D- and D+ are tied
together (sometimes shorted, sometimes with a resistor), and there maybe
be resistors between those pins and +5V / GND, too. AIUI, if a device
sees that D- and D+ are tied, it takes that to mean that it's connected
via USB to a charger, rather than something that it's expected to
communicate with.
Sometimes the tieing / resistors are buried within the USB connector
itself, but sometimes it's done back at the PSU and the 4-way cable/
connector are just straight-through.
If you've got the former, you just need a 2-way connector in the
dashboard, because the USB connector (which I assume you'll still be
using to connect to the Tomtom itself) contains all the needed gubbins.
Lots of robust 2-way connectors exist.
For the latter though you'd need a four-way connector of some form - I'm
not sure what would be best there.

Thanks - I wasn't certain what would be in the cable connecting the
charger to the USB socket. Obviously, it's only needed to supply the DC. I
could just hack the cable in two and use a connector for the number of
cores, one to one. But on the old TomTom, there were three wires - one a
sort of voltage sensor which was linked to one of the other wires at the
output - but it worked fine with two so I got away with a two pole plug
and socket. Since the lead beyond that was only a couple of inches long.

--
*The hardness of the butter is proportional to the softness of the bread *

* * Dave Plowman * * * * * * * * London SW
* * * * * * * * * To e-mail, change noise into sound.

you may well find that it chargers fine with just the 2 power pins,
the shorting of data pins is to allow for a higher current draw (more
than 500ma)

Possibly worth bearing in mind that if it's expecting usb power, it is
probably expecting a smooth 5v, there may not be as much in the way
of power filtering/regulation inside compared to say a device
expecting a 9v wallwart

Martin