[Che]

I bought a 12v socket --> USB adaptor from jaycar yesterday to power up the iPod in the car. I have the ipod connected to the car stereo via an aux in. But, if I have the iPod running and recharging at the same time I get some wierd computery electro interference through the speakers. Pull out the power and music playback is peachy again.

Is this a grounding issue?

[Kermy87]

It's the transformer in the USB making ellectrical noise, kinda the same as an old tv if you ran a 240v power drill near it,, it went ape shit, not alot you can do about it, mine old one done the same thing, then I just bought a proper fusion iPod intergrated head deck, problem solved,

[Moph]

100% normal. You can fit a line noise filter to the radio (Jaycar stock them) which will help but you'll likely still have a high pitched whine. I just avoid charging the iPod while I'm using it.

[pyrohamish]

Something that might work would be setting the audio ground the the vehicle ground.
I have this same problem, havnt tried to fix it though, just avoid charging and listening.

[royce]

see if you get a buzz using headphones while charging from your usb doohicky

[Che]

royce wrote:

see if you get a buzz using headphones while charging from your usb doohicky

I just tried this - no noticeable noise in headphones, but right there when you plug back into the aux in.

[royce]

its an earth loop then, hum created by 2 different signal earth points, try earthing the usb and radio to the same point (in theory works, in practice it doesnt)

Or try a ground loop isolator, though by the time you stuff around getting one and converting the RCA ends to 3.5mm youve spent a lot of money