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Avoiding ground loops in WOS timing sensor

Pgram

By Pgram
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Pgram New Member

Pgram

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Hi all,

I'm using WOS 1.3 and I like it very much.

I had some problems (freezing oscilloscope view) on a particular laptop (Lenovo with Realtek soundboard) so I moved it to an Asus Laptop; no more problems.

I noticed that my old Timetrax ticking sensor was picking up a lot of noise from the surrounding ambient, surely related to 50 Hz mains and other sources, like LED lights.

I looked at the cable connections: There were only one "hot" wire and a shield, connected to both the piezo ground side and the plug ground side.

That creates what Audiophiles call a "ground loop", acting as an antenna to pick up the noise.

So I replaced the cable with a good quality shielded Microphone Cable, with two wires inside and a good shield.

The shield was connected ONLY to the plug ground side, and left "floating" at the sensor side; that's the important trick.

Now the noise is reduced to near zero; I checked with an oscilloscope, and by hearing it at the output of the Timetrax amplifier.

Hope that this will help some of you,

Paolo from Italy

 

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