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From: email@example.com (Bill Sloman)
Subject: Re: Cheap low frequency impedance bridge?
Date: 13 Oct 2002 14:15:10 -0700
References: <3DA6E7D6.firstname.lastname@example.org> <email@example.com> <3DA84D7D.firstname.lastname@example.org>
NNTP-Posting-Date: 13 Oct 2002 21:15:10 GMT
Fred Bloggs wrote in message news:<3DA84D7D.email@example.com>...
> Bill Sloman wrote:
> > The Analog Devices AD9854 DDS chip that produces tightly coupled
> > in-phase and quadrature outputs
> > http://products.analog.com/products/info.asp?product=AD9854
> > is exactly what I'd love to be able to use - much neater (though
> > probably no more effective) than the scheme Win Hill set around two AD
> > DDS chips.
> I cannot believe that you require ppm accuracy in measurement of a
> parameter, indicative of wearout, that deviates over a 10:1 range.
We certainly don't require ppm accuracy - we couldn't exploit it
unless we set up much better temperature control. The range on the
parameter isn't its deviation, but the range within which we might
want it set.
> If you can adjust the frequency to 200KHz for measurement of R with
> adequate accuracy, then you certainly have the bandwidth for measuring
> the time constant of a step response. Why isn't this good enough?
The electronics we use with our transducer is fast, but low-powered
and simple. What I'm looking for is an off-the-shelf quality control
tool for transducer development and production. As I've mentioned, I'd
love to develop one for myself, but it would be an extravagant waste
of time and money. Even buying an Agilent 4284 would be cheaper, and
Bill Sloman, Nijmegen
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