Re: Dimmer as a Variac.

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

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

As it happens, the dimmers (or fan speed controllers, which might actually
work better, since they drive a somewhat inductive load) made by Lutron are
typically better than those from Leviton. In a former job a few years ago,
we were looking for replacements for 5A variacs to control a 1/3 HP PSC
motor.  We went through many, many commercially available dimmers.  As you
noted though, the construction quality is a bit iffy, although, to be fair,
we never had one (out of hundreds) fail because of construction or
workmanship defects.

The slightly more expensive units (i.e. more than $5) also usually have an
inductive snubber/RFI filter in them, which the cheaper ones don't.


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Friday, July 06, 2001 7:32 PM
Subject: Dimmer as a Variac.


> 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
>
>