Re: Dimmer as a Variac.

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Metlicka Marc by way of Terry Fritz <twftesla-at-qwest-dot-net>" <mystuffs-at-orwell-dot-net>



Tesla list wrote:
> 
> Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<evp-at-pacbell-dot-net>
> 
> Tesla list wrote:
> >
> > Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>
> >
> > Hi All,
> >
> > Today I got a Leviton No. 6681 600 watt dimmer switch at the hardware
> > store.  It cost me about $7.  I imagine these are available everywhere at
> > least in the USA.  I pulled the back cover off to expose the electronics:
> >
> > http://hot-streamer-dot-com/temp/P7060004.jpg
> >
> > Wow!  They sure are cheap!! :-))  All hand tack soldered.  Many
> > opportunities for shorting and such...
> >
> > The main power electronic device does not have heat sink compound under it.
> >  I think drilling out the rivet and adding a little thermal grease will
> > increase it's short term power handling about 200%!
> >
> > Not enough room inside to add internal MOVs but a little thermal grease and
> > some "adjustment" of the guts should help them to survive considerably.
> >
> > I am thinking that MOVs and a good line filter will complete the poor man's
> > variac and I can do a little testing to see if the idea is worth while.
> > Still have to check what the output wave forms look like and see how that
> > will affect the rest of the coil...
> >
> > Stay tuned...
> >
> > Cheers,
> >
> >         Terry
> 
>         I predict you are going to be very disappointed!  The performance
of an
> SCR/TRIAC dimmer is very different with an inductive load, which your TC
> primary circuit will probably be at the frequencies which commutate the
> SCR.  Hope I'm wrong.
> 
> Ed

ed,
the scr based phase proportioning setup that i have states that it is
used for resistive AND highly suited for inductive transformer loads. i
am glad that there is so much interest in these for tc use now, when i
brought it up a couple years ago i received no replies?
i have scanned in the pages of the operation and service manual at high
res. and if terry wishes i could send on to post on his site?
i am missing the last page witch was the parts list, but a couple high
resolution pics of the front and back of the boards (witch are
conductive pen traced and hand soldered) should provide enough for a
very easy reverse engineering to build these 3.6kva current limiting,
voltage controlling units. this one offers a soft start feature and
since vectrol is out of business, i don't think we would be stepping on
any toes?
this thing is very simple looking with a good explanation of operation
in the manual, i'm still looking for the last page that must have came
unstapled?
i would much like to get some help in breaking this unit down so that i
could try to build one that uses the 15kv\400amp scr's that i have. if
anyone wishes to help me reverse engineer this unit i will give a set of
the scr's for the labors.
let me know at mystuffs-at-orwell-dot-net  and terry, let me know if you wish
to post the pages with schematics?
marc m.