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

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?



Best Answer 8 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.

eh...you 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.

What does the noise sound like?
You could be sending too hot of a signal to your stereo.

The problem is not the signal, because when I use the laptop stand alone, not connected to the car power, it works fine.

.  Before going to all that trouble, try using shielded cable(s) between the laptop and stereo.