RE: Variac rating

["Andy Cleary" <gemware2-at-xxxxxxxxxxxxxx> (by way of Terry Fritz <twftesla-at-xxxxxxxxxx>)]

Hi green horn!  Just to give you an idea about the size you are looking at,
I have a nice powerstat 120 VAC 1.75 A variac that I bought a while back.
It's dimensions are 2" tall and 3" in diameter.  With knob, it is about 3.5"
tall.  If you would like to see what it looks like - let me know (I just got
a small digital camera, and I love using it!).  I also have another medium
size variac, rated 120 VAC 6A.  It's dimensions are 4" tall, and 5" in
diameter.  (5.5" tall including the knob).  And, that nice variac I happened
to find on my school's "Loading Dock" inside a strange piece of equipment.
Frankly, I'm not sure what it was - it had a seismograph-style printer, and
UV radiation stickers on it.  It also had a nice variac, some meters, fans,
heatsinks, transistors, etc. in it - so I scrapped it out.  But if you
attend a fairly well funded school, if you keep an eye out, and if you know
the right places to look, I'd say you could come up with something usable.
On a similar note, I also found a huge 0-140V 50A variac - perhaps for
current limiting?  I hope that helps, and let me know if you want more info!

-Andy C.

-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Thursday, November 23, 2000 11:54 AM
To: tesla-at-pupman-dot-com
Subject: Variac rating


Original poster: "Nathan Morris" <themfam-at-home-dot-com>

All,
I am new to the list and find it to be an excellent source of answers for my
unasked questions.  I am contemplating my first Tesla Coil and need all the
help I can get.  I have decided to go with a small DC tube driven TC.  Mark
S.
Rzeszortarski Ph.D. has a diagram on the web of a VTTC that he can run for
long
periods of time with out serious problems.  I plan to loosely base my TC on
his
design.  The question I have is about the current rating for my variac which
will have a 120V input and will have it's output tied to a high voltage
transformer.  The transformer output to the diode bridge rectifier is 600V
AC.
The variac on the diagram is notated
0-120 VAC 1.75 A.  I want to keep the components for this project as small
as
possible.  With respect to current, what size variac does it sound like I
need?
I am another EE student without allot of cash and about the only thing I can
afford to order from Jameco is their free catalog.  Does any one have any
suggestions on what I might be able to scrap one out of?
Because Safety comes first I feel like it might be to my advantage if I tell
the list members a little about my background.  I have over 4 years of
experience in the commercial electrical trade.  I am not a licensed
journeyman,
but I spent over a year as a N.A.L.M.Co. certified senior technician
troubleshooting ALL types of commercial lighting systems and controls
including
High Intensity Discharge lighting, neon and signage.  Before enrolling at
the
University of Texas I spent two years studying electronics at a technical
school.  I am fully aware of the hazards involved with my project and plan
to
use extreme caution.

--green horn