I have one of the early TomToms - the type which are quite deep.
Disliking having wires trailing, I fitted the PS inside the instrument
nacelle and installed a socket in the nacelle cover - the same as the one
on the TomTom. Made up a short lead from it to the TomTom. Looks just fine
- and despite the warnings about the extra volt sensing wire it's worked
great for years.

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? In other words, cut the output lead from the new PS and use some form
of connector to get it through the cover, and use the cut off end of the
lead as a tail.

--
*Why is the word abbreviation so long? *

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

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.

cheers

Jules

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.

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

"Dave Plowman (News)" :
I have one of the early TomToms - the type which are quite deep.
Disliking having wires trailing, I fitted the PS inside the instrument
nacelle and installed a socket in the nacelle cover - the same as the one
on the TomTom. Made up a short lead from it to the TomTom. Looks just fine
- and despite the warnings about the extra volt sensing wire it's worked
great for years.

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? In other words, cut the output lead from the new PS and use some form
of connector to get it through the cover, and use the cut off end of the
lead as a tail.

I'd slit the sheath just where I'd be putting the connectors, to find
out how many cores there are. If you're very lucky there will be just
two.

--
Mike Barnes