On Mon, 14 Sep 2009 22:00:11 -0700, Mike Bamberg wrote:

There have been several individuals that have taken apart the HP-
supplied car charger and there ARE non-standard (as defined by the USB
spec) voltage divider resistors in the circuit on the charger side. This
provides a signal set to the device (throught the cable) to trigger it
to use the high current mode on the device. If you plug the device into
a standard USB port on the computer it will not charge at the same rate
as with the HP charger. If you plug it into another vendor's car charger
there is no guarentee the device will operate in high current mode.

.....

In short (pun intended) the HP design has many "safe guards" to insure
that the device does not use high current mode on a device or port that
cannot supply the needed current. Or with a cable that may not be
designed for the higher current.

That's fair - IOW the device can be charged from a standard USB 2.0 port.

Have you any idea what its current draw is when not charging (i.e. fully
charged) and set to high brightness.

I did say at the start that I was using an iPAQ 36xx car adapter to run
my Binatone. I originally came with an iPAQ multiway connector and is
rated at 1.4 amps at 5v - or more correctly, that's what the 3630 manual
says it can draw.

FWIW, when I pulled that PSU out of the cigar lighter plug shell and
added it to my data distribution box, I wired it to a D-9 socket. Thge
remains of the original cable and the Binatone cables were modified to
have a D-9 plug on the PSU end.

Looks like I should modify my advice: get an iPAQ car adapter and use the
electronics out of that: they provide 5v with enough current to keep an
iPAQ happy. eBay is offering Belkin units for around $6.00 and genuine HP
units for $25 or so (these are UK 'Buy It Now' prices).


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |