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From: crandell@ut-sally.UUCP (Jim Crandell)
Newsgroups: net.analog
Subject: Re: Adding Video Input to TV.  Summary
Message-ID: <3830@ut-sally.UUCP>
Date: Mon, 16-Dec-85 23:57:08 EST
Article-I.D.: ut-sally.3830
Posted: Mon Dec 16 23:57:08 1985
Date-Received: Fri, 20-Dec-85 01:02:17 EST
References: <6770@amdcad.UUCP> <3500001@Clio> <610@ttrdc.UUCP> <34212@lanl.ARPA>
Reply-To: crandell@sally.UUCP (Jim Crandell)
Organization: U. Texas CS Dept., Austin, Texas
Lines: 23

>> More to the point, yes it's cheaper.  And less efficient and it has less power
>> handling capability, perhaps on the order of a 10-20% loss in voltage
>> (due to resistive voltage losses in the windings which are not made up in
>> an increased secondary turns count since the two transformers are obviously 
>> symmetrically ratioed)...

Not to be a wet blanket or anything, but I vaguely recall that the ``standard''
isolation transformer of years past actually did have a slight step-down;
seems like 117:110 was the most common spec.  In most areas, a voltage
reduction is not really such a bad idea -- the line voltage at my place
averages about 123, for example.  For equipment using tubes (forgotten what
those are?  So you really enjoy editing on that Decwriter, eh?), it's
particularly unstupid, in fact.  (This topic leads rather naturally into
a discussion of classic methods for extending tube filament/cathode life
expectancy.  One of the most common of these is particularly obvious by now,
I would think.)  Besides, if you're gonna shell out for a pair of 60-watt
filament transformers, you might as well buy an isolation transformer.
It probably won't cost any more; it occupies less space; and it emits
less heat.
-- 

    Jim Crandell, C. S. Dept., The University of Texas at Austin
               {ihnp4,seismo,ctvax}!ut-sally!crandell