[R-390] Isolation Transformer update

[Scott, Barry (Clyde B)]

I agree.  I don't like to leave wallwarts plugged in unless it is for
something needful like charging the cordless phone, etc.

As far as this 1KVA isolation transformer is concerned, everytime I try to
hang it on the wall, it falls out of the recepticle.  :)

Seriously, the isolation transformer will only be switched on when the shack
is in use.  Everything goes dark when I leave the shack for the evening.
Too many things to worry about out there that a single flip of a big switch
doesn't take care of.

Barry(III) - N4BUQ

> -----Original Message-----
> From: Barry Hauser [mailto:barry@hausernet.com]
> Sent: Thursday, November 06, 2003 11:36 AM
> To: Scott, Barry (Clyde B); R390 (E-mail)
> Subject: Re: [R-390] Isolation Transformer update
> 
> 
> Don't know how typical that is -- doesn't sound unreasonable. 
>  But then,
> that's why power is switched at the primary .... except for a 
> lot of new
> stuff.
> 
> Wherever wallwarts are used, there's a constant drain even 
> when the devices
> connected to them are turned off.  Originally, these were 
> mostly for use
> with small devices that were otherwise battery operated and 
> mostly on a
> part-time basis..  However, there are many AC only as well as portable
> equipment with wallwarts whether they make sense or not.  
> That's so the
> manufacturers don't have to design for mains voltage and 
> UL/CSA/CE approval
> for the unit itself which only "sees" low voltage AC or DC.  
> Also makes it
> easier and cheaper to provide for various domestic supply 
> voltages by simply
> packing the appropriate wallwart in the box.
> 
> Though well forgotten by now  (pre-9/11), one of Dubya's 
> early speeches
> about energy conservation called these things "power 
> vampires" that consume
> even when not in use.  And that's because the primary is 
> connected 24/7.
> Look around -- most computer accessories, even tabletop communications
> receivers, cordless phone bases, you name it.  Probably 
> average about 10-20
> of these things per household.  Leave 'em all plugged in, 
> turn everything
> else off, then go read your meter.  I suppose it can add up.  
> (Touch some --
> see how warm some of them run on idle.)
> 
> While most of the wallwarts have some kind of approval 
> marking, most all
> have no internal fuse or thermal breaker.  If they fail, most 
> will begin to
> burn up well before tripping a 15 or 20 amp breaker.
> 
> Gettin' old here.  Just mention something about primary 
> windings drawing
> current with no load .. and I run off at the keyboard on a 
> wallwart rant.
> Don't you just love the ones that don't have the 
> manufacturer's name or
> model number, so when you disconnect a bunch ....  nevermind. 
>  I'm starting
> to sound like Andy Rooney.
> 
> So you were saying?  350 ma unloaded?  Don' t look know but .... ;-)
> 
> Barry
> 
> 
> 
> ----- Original Message -----
> From: "Scott, Barry (Clyde B)" <cbscott@ingr.com>
> To: "R390 (E-mail)" <R-390@mailman.qth.net>
> Sent: Thursday, November 06, 2003 9:46 AM
> Subject: [R-390] Isolation Transformer update
> 
> 
> > I did some experimentation last night.  With no load and 
> the primaries
> > connected in parallel at the 120V tap, the primary drew 
> about 350mA.  At
> the
> > 110V tap, it drew almost 500mA.
> >
> > I then connected the series 75W light bulb.  The 120V tap 
> caused a dull
> glow
> > while the 110V tap produced about twice that brightness 
> (although still
> > quite dull).
> >
> > I didn't attempt the primary at the 104V tap.  I did notice the
> transformer
> > produced a bit more hum at full voltage when at the 110V 
> tap than at the
> > 120V tap.  I did not notice any heating, but I didn't leave 
> it on very
> long
> > either.
> >
> > Do these results sound typical?  I've never examined the 
> primary current
> > draw on a transformer at no load.
> >
> > Thanks,
> >
> > Barry(III) - N4BUQ
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>