I've been a lurker here and finally decided to pop my head above the parapet.

So, a bit of background.. I've got a Euro Ford Focus. It's got an aux-in for the car stereo.

I was considering getting an "IO Play" bluetooth stereo carkit to connect my iPhone to the car stereo - since I use my iPhone to listen to music and have Navigon satnav should I need it..

The problem is you still need to charge the device, so I figured since a cable was needed anyways, I'd try to find one that combined charging with aux-out via the dock connector.

Not easy! But I found this cable:

Although its actually for a Kenwood headunit and lets you control the iPod over USB, aux-out and charging (via a USB cigar charger) are confirmed to work.

Now to my question. I'd like to hide all the charging gubbins behind the dash. The access to the cigarette lighter socket isn't good at all, so I was wondering if connecting my step down circuit to the car stereo's 12+ Ignition line was ok? The current isn't going to blow any fuses is it?

If you think is /will/ blow a fuse, can you suggest anywhere else to take power from?

And finally, at the moment I'm using the guts of an old cigeratte USB charger for my power, are there any links or pointers to building such circuits yourself?

Thanks for the help guys. Great - and informative - forum.