[filmscanners] Re: Power Line Filter

["Owen P. Evans" <opevans@ca.inter.net>]

Hello Austin et al,
I stand upon my convictions here. The paper Howard alluded to described the
guy buying an RFI filter!
EMI interference should be taken care of by the engineer who builds the
power supply. If the main voltage to the product is lacking, the power
supply should accommodate the differences, plus or minus a few volts. If RFI
interference is present then graphite beads or rings around the power cord
will eliminate this.
All in all the voltages being amplified in a scanner are nothing like audio
preamp requirements. I still believe the audio nervosa syndrome is at work
here. Oh yeah, it's still hogwash!

Owen
Owen P. Evans
Osgoode, Ontario. Canada
(near our nation's capital; Ottawa)


----- Original Message -----
From: "Austin Franklin" <darkroom@ix.netcom.com>
To: <opevans@ca.inter.net>
Sent: Friday, March 29, 2002 10:54 PM
Subject: [filmscanners] RE: Power Line Filter


This is absolutely NOT hogwash.  It's called EMI, Electro Magnetic
Interference.  It is VERY well known to exist, and cause the exact problems
mentioned.

I have not experienced scanner noise with my scanner, but it is designed
such that this will not be an issue.  That does not mean that no scanners
don't have these problems.  It is very believable, and in fact, likely.  The
scanner has very sensitive analog circuitry in it, that operates at micro
volts, and as such, poorly designed, is VERY susceptible to EMI.

It is also very different than a log of the audio silliness with Shitake
stones and magic wands.  This is based on sound (or not so sound in the case
of poor design) engineering principles.

Austin




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