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Re: Variac Wiring




From: 	Jeff W. Parisse[SMTP:jparisse-at-ddlabs-dot-com]
Sent: 	Monday, December 08, 1997 10:15 AM
To: 	Tesla List
Subject: 	Re: Variac Wiring

Adam,

Pin 1 (common) and pin 2 are the inputs for 0-140V output.
Pin 1 (common) and pin 4 are the inputs for 0-120V output.
The output is between pins 1 (common) and pin 3 (wiper).

Follow, in you diagram below, how the wiper moves down
from pin 1 (0V) towards pins 2 or 4 (depending how the variac
is wired for output) and you'll see how it works...  The extra bit
of winding at the end gives us that 20V boost when the variac
is hooked up for 0-140V operation.

Pin 5 allows us to hook the whole thing backwards for
counterclockwise operation. Notice the symmetry...

Jeff W. Parisse, Art Director
Digital Design Laboratories
www.ddlabs-dot-com

>
>I had to take apart my variac (Powerstat 116, 120V 7.5A 1PH) today to 
>replace the switch, and when I removed the housing, I found two 
>unconnected terminals numbered 4 & 5.  The schematics seem to be like 
>this:
>
>      ____ 1
>     (
>5 ___(
>     (
>     (
>     (<--- 3
>     (
>     (
>     (
>2 ___(
>     (
>     (____ 4
>
>The variac was originally connected to the mains at 1 & 2, and to the 
>outputs with 1 & 3. This gives a maximum of 140V.  If I connect the mains 
>to 2 & 5 and the outputs to 1 & 4 I get about 170V.  Any reason for these 
>extra bits of winding?
>
>-Adam
>
>--------------------------------------------------------------------------
>Adam Smith
>absmith-at-tiac-dot-net
>Epoch, Inc. Digital Music Project
>
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>--------------------------------------------------------------------------
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>