Hum differences in toroidal power transformers...

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Hum differences in toroidal power transformers...

Post by Crusty » Mon Apr 20, 2009 5:57 pm

Observations and not a scientific experiment by any means but...

I had, on-hand, three different brands (two or three of each brand) of stock toroidal transformers from Amveco, Avel-Lindberg, and Multicomp. All were15V 50W ratings. I swapped them into a PSU connected to a circuit pulling about 25W. The output was patched into a set of headphones. and I rotated the transformers for minimum hum.

The Amveco was by far the noisiest, even after wrapping it with a layer of steel banding. The Avel came in second to the Multicomp which turned out to be very quiet - I could null the hum below the noise floor to where I couldn't hear it at all. I can't give any hard numbers cuz my test gear does not measure down that low. The Multicomp was a bit suprising to me because it was also dimensionally, the smallest of the three. Of course, I'm only looking at one parameter here, stray field...

The leads dress out differently on the Amveco than the other two, I wonder if it's wound differently...
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Re: Hum differences in toroidal power transformers...

Post by » Fri Apr 24, 2009 12:12 am

from what ive read, it is the leads on the breakouts themselves that cause most of the noise, so maybe that could explain the difference?

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Re: Hum differences in toroidal power transformers...

Post by mediatechnology » Fri Apr 24, 2009 8:25 pm

What was the harmonic content of the fields? Could it be an issue of core saturation?

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