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I am an iPhone developer and I have to have the phone near my Mac.

My Mac headphone (mini-jack) output is connected to my TV audio in (mini-jack). I have this for years and I always worked near my old iPhone 3G without problems.

Since I bought an iPhone 4, now I listen an annoying interference, like white noise, on the tv speaker. I mute the TV and the problem vanishes. I remove the SIM card from iPhone 4 and the problem is solved, but I cannot disable the iPhone, as I use it to test and it have to stay near the computer/TV (the TV is my secondary display). No, the TV has no optical input, so I have to continue using this input. No for the second question you may ask too, that is, my mac has a mini-DVI video out that do not carries audio, so I cannot use mini-DVI to HDMI, because I will have no audio. So, I am stuck with mini-jack audio from Mac and on TV.

Is there something I can do to solve the problem? Some shielded cable or something, that can block the cellular signal from entering on the cable and being heard on the TV?


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up vote 1 down vote accepted

Try a snap-together ferrite choke (a.k.a. "ferrite core", "ferrite bead", "choke core", etc.). You can get them for $3 for a pair from Radio Shack.

Snap one onto the audio cable at the TV end of the cable. It'll probably fix the problem, and even if it doesn't, it's an inexpensive test.

Now that you know what one is, you might be able to harvest one from some old cable you have lying around that you don't need anymore. You could probably cut it out from the plastic with an X-Acto knife or Dremel Tool. However, you'd want to find one that looks like it was made in two halves; many of the cable-integrated ones are a single piece, and probably won't slip over the end of your audio cable.

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Thanks! I found one here, installed and the problem reduced a little bit, but while I was installing it, I discover the problem was stranger than I thought. The interference makes speaker vibrate and that vibration makes the metal plate at the back of my Tv to vibrate too. That vibration is what I was hearing. I pressed the plate with my finger and the noise vanished. The problem is that this is a barely brand new TV, with less than 3 months. I tapped the plate with my finger and now the noise is gone. Thanks anyway. – SpaceDog Sep 23 '10 at 19:51

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