Advice About Noise Supression

[GLPoomobile 958]

Nothing to do with a 205, but hoping someone who understands electronics and ICE might be able to advise on this.

 

So the scenario is thus.......I'm fitting a phone cradle to the dash of my V70. This cradle (an iBolt xProDock) has a product specific charging/data(ish) lead, that connects to your phone via a micro USB 2.0 plug at one end, and at the other end has a standard USB 2.0 plug and a 3.5m jack. The intention (obviously) is that you connect the USB to charge, and connect the 3.5mm jack to your aux port to stream music. Now in my case I plan to route this lead immediately in to the dashboard and connect it up permanently behind the headunit, as back there I have the necessary aux port via a CD changer interface.

 

So I need to connect the USB up behind the dash too. One thought (albeit very Heath Robinson) is to take a spare universal 12v accessory socket and splice it in to a switched live behind the dash (perhaps even the existing cigerette lighter socket), then add a 12v-USB charging adapter to that, then plug in the USB, and tape it all up real nice like, just like the best car alarm installer would.

 

The other option is to fit a dedicated accessory that I've seen online in various forms, which comprises of the 2 wires for 12v DC and ground, in to a little black box consisting of about 23 pence worth of electronics) and then a USB female plug out the other side. It's simple and tidy. But I do have concerns about quality given the dubious origins of these unbranded products, and have an image in my mind of my car going up in flames one evening.

 

With either approach, am I likely to introduce alternator whine when streaming music from the phone, and is there anything I can do to prevent this. I've heard of people using suppressors, but I just don't know enough about such things.

[GilesW 41]

I know this is not the input you're after - but I'll comment anyway as I've been in the same situation some years ago:

 

I considered doing all this, with all the ifs, buts, and maybes.

 

Then just bought a parrott kit and installed it.

 

No hassle.

No nasty cradle.

No splicing of wires or installing a 'will it burn' china product.

No interference.

 

And just transfer from car to car.

 

Anyhow if you are fixated on installing to your spec I would definitely be installing a branded USB power supply as I've had a few china SUB wall chargers get roasting hot/cut out, so no way would I be happy to hide one away out of sight.

[GLPoomobile 958]

Thanks Giles.

 

Just typed a big load of twaddle that's probably not interesting to anyone, so here's the abbreviated version.

 

1) I don't want Parrot. For my own reasons

2) I'm a twat. For overcomplicating things.

3) I think I can pull power from the wee CD Interface box behind my dash (which has USB, SD, and 3.5mm aux in). This didn't work when I tried before, but I think I know why now.

 

I think (I hope) that the USB cable that comes with the iBolt cradle will be a charge only cable and will therefore only use the outer two pins of the USB connection (the inner two are for data). If that's the case, then I suspect that I can draw power over USB from the CD Changer Interface. I tried this before with a USB data cable and both my phone and the headunit had a bit of a fit as the interface obviously saw a data source had been connected and was scanning for files, but wouldn't have found what it was looking for.

 

If that works out OK, then my concern still remains over whether I'll experience alternator whine. My googling suggested that this is the result of a ground loop and the accessory used to supply the power needs to be better grounded.

[welshpug 1,657]

Interesting subject, I'm also experiencing some whine when I've got my phone plugged into a certain dooberry in my BMW, my brother works in A-V and mentioned filters which would go on the Audio output of said phone (I use it as an MP3 player, and hands free)

 

I've not tried an alternative power source, as it might be the charging thing I'm using causing it.

[MikeC 10]

Try a cylindrical ferrite core around the power side of the new unit, to suppress the noise. Just maybe wrap the power cable through and back around again to be sure. Cheap and easy way of trying to eliminate the noise. You can see them moulded into power cables for AV equipment.