How can I make a filter in the audiocable between my laptop and car stereo to avoid the noise I now get.?

When I connect my laptop to my car stereo  I get a lot of noise. I suspect there is some kind of loop between the laptop power supply and the amplifier. I think I can solve the problem by using a filter in the audio cable to separate the two, perhaps by means of a transformer. Does anyone have a good circuit design for this?

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Re-design8 years ago
Are you powering the laptop using a plugin power to the car power?  If so you may have  ground loop.  You can get a ground loop filter at a car stereo shop.  Might fix it might not.

As redesign said, there is a device called an "Audio System Ground Loop Isolator" which *used to be available at Radio Shack under the "Archer" brand name, that will isolate the grounds between two systems. I have one connected to my old Tascam Porta 4 and the computer. It's basically just a dual 1:1 transformer with shielded audio cable attachements (mine is RCA jack terminated, so you may or may not require additional adapters for your system.)
Thanks, sean.  I couldn't remember what it was called and I've never had one open to see what was there. had the answer. I just gave it a brand name. The graphic on mine shows that it's a dual channel transformer...I'd up a pic but had to giveup my camera to my younger brother for a while, and I have yet to reinstall all my logitech drivers so the webcam is down as well..

I originally bough it to connect the output of my soundcard to my PA for outputting my midi comps thru an external effects processor during the early 90s.
asdterror8 years ago
What does the noise sound like?
You could be sending too hot of a signal to your stereo.
ardnaz (author)  asdterror8 years ago
The problem is not the signal, because when I use the laptop stand alone, not connected to the car power, it works fine.
NachoMahma8 years ago
.  Before going to all that trouble, try using shielded cable(s) between the laptop and stereo.