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Ground Loop Isolator?

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BigB9k

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I'm working on a circuit that switches audio for and MP3 player to Radio.
After doing some testing, I noticed a slight 'hum' when music wasn't being played.
I guess this is a common problem with shared grounds in audio/video equipment.
turns out I need a 'Ground Loop Isolator' Mouser has this, which sounds like it'll do what I want:

http://www.electro-tech-online.com/custompdfs/2011/01/EC100.pdf

But I don't understand how the whole shebang works. Is this isolating the ground? Audio left and right? all? Does it need its own power source?
More questions to come....
 

Diver300

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Those won't work at audio frequencies. They are designed to work at much higher frequencies and will saturate at the low frequencies you would be wanting.

I think that a differential input amplifier is what you want.
 

MikeMl

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Those won't work at audio frequencies. ...
Yes they do, and they work very well. I have installed many in aircraft entertainment systems. If you try to power a CD or MP3 Player from the aircraft's power system, and then couple the audio into the headphone amplifier, since the DC power ground in the MP3 player is common to the audio output common, your hear alternator whine in your music... Putting in a audio transformer-based ground-loop isolator breaks the ground loop, and gets rid of the alternator whine.
 

MikeMl

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Last edited:

MikeMl

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The link in the OP is for an ethernet transformer.
The OP's link doesn't work for me, so I just assumed he was referring to an audio ground-loop isolator...
 

BigB9k

New Member
The OP's link doesn't work for me, so I just assumed he was referring to an audio ground-loop isolator...
yeah its weird, it was working earlier...

Looks like that was the wrong isolator anyway.
Looks like all thats needed is a 1:1 transformer?
 
Last edited:

MikeMl

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...
Looks like all thats needed is a 1:1 transformer?
The commercial ground-loop isolators like I linked to contain TWO transformers (stereo)
 
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