[sdiy] isolating variac unit

[Roy J. Tellason]

On Friday 02 November 2007 22:12, KA4HJH wrote:
> >Second update is an AC voltage meter. Does it really matter for
> > Variac-type uses to have a true RMS meter or could I just rectify and
> > filter it and show that voltage.
>
> Meters are most useful if you're working on power supplies. As you dial it
> up a sudden drop in voltage/increase in current means something just
> shorted.

Maybe.  Or maybe something just hit a threshold of activity.  I notice that 
switching supplies don't like variac-controlled power input,  for example,  
and don't seem to do much of anything until you get up around 50-60% of full 
output.  :-)

> A set of loads is also good to have for PS work. Roy's ballast
> bulb sounds like a good idea.
>
> I've been trying to get one of these put together for myself but never
> found the right enclosure.

The bulb I'm using is too darn small.  It's a small-based bulb screwed into a 
standard socket with an adapter,  and it's only 40W,  but I can connect a 
larger bulb in parallel with it using the binding posts if necessary.  For 
much of what I work on it suffices,  though.

Loads?   That can be all over the place depending on what sort of gear you're 
working on.

-- 
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