[NJARC] Vairac and Isolation Transformer questions

[Scott Roberts]

This should be easy for most of you guys, but I am
still working (again) on my shop equipment...

First, I picked up a Variac (Superior Electric Co.
Type 20) and Steve gave me a quick rundown on
connections, but, of course, it has alredy
evaporated(brain dump after a fun day...lol) It has 5
connections. #1 & #5 are the tap outs from 1/4 of the
way either side of the end of the coil. #3 is the
rotating brush. #2 & #4 are the two ends of the coil.
The important sections of the decal are missing, so I
need to know how to connect it... I seem to recall
Steve telling me one of the tap-outs gives a step up
voltage. I am assuming(!) the cold side of the line
voltage connects directly to the cold side of an
output socket, and the hot side goes to #4(for
Clockwise operation), with the hot side out going to
#3. Could anyone please confirm or correct this
assumption?

As to the isolation transformer, last time I tried to
use it, it was not quite happy, so I am replumbimg the
in and out...Originally, it had a voltage in of
110+-VAC, with outs of 105VAC, 115VAC and 125VAC. My
line voltage is about 119VAC. I think the transformer
is suffering a little age- the outputs are now 115VAC,
125VAC and 135VAC. I probably have no need of
135VAC... I am thinking of changing out the original
switch- which is a modified octal socket & power plug,
where you remove and turn the plug to set voltage. I
am going to put on an SPDT and just connect the 115 &
125 voltages. Also, it has a separate ground
connection, and an ungrounged single plug socket. I am
thinking of putting in a grounded double socket, one
with direct line voltage, the other with the isolated
voltage, and connect the ground as is now common. Do
my concepts sound reasonable?

One last question: I am also working on my
oscilloscopes, and am having the problem of them
having an irregular wave, and also I can't get the
horizontal position correct- on all of the, it stops
to one side of center, and will not move... Does this
sound like cap or electrolytic issues?

Thanks!
Scott


       
____________________________________________________________________________________
Take the Internet to Go: Yahoo!Go puts the Internet in your pocket: mail, news, photos & more. 
http://mobile.yahoo.com/go?refer=1GNXIC