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Subject: Re: Looking for cheap isolation transformers
Date: Sat, 19 Oct 2002 17:12:52 GMT
NNTP-Posting-Date: Sat, 19 Oct 2002 13:12:52 EDT
"Philip A. Marshall" wrote:
> If I'm using a 1:1 transformer, it shouldn't change the input
> impedence, right?
Wrong. You start with an input impedance of ~100K.
You add a 1:1 transformer. That 1:1 is a turns ratio,
not an impedance rating. Say the transformer is rated
at an impedance of 600 ohms. So your new input impedance
after adding the transformer, is 600 ohms.
> My point is not to change the output impedence, but to break the
> direct ground connection from input to output, sortof like the same
> reason isolation transformers are used to prevent people being shocked
> in the case of a fault.
But ground loops are external to the equipment. To
solve ground loop problems, you are not looking to
isolate the path from input to output. You need to
wire things such that there is a single ground path
for all equipment in the system. Throwing isolation
transformers at it may work - but it is best to
understand where the loop is created and address
the specific problem. Say you do end up needing
an isolation transformer - it's better to pay for
just 1 than for multiples!
Don't get me wrong - I think experimenting as you
intend to do is great. It's just that I get a
sense that you might be missing the real issue.
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