Re: strange variac

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

Original poster: Terry Fritz <teslalist-at-twfpowerelectronics-dot-com>

Hi Andy,

This is the sheet from PowerState but maybe it will be of help.  With 7 
terminals, it was probably made for 240 OR 120 VAC input and any rotation:

http://hot-streamer-dot-com/TeslaCoils/Misc/VarBack.jpg

Maybe like figure "B".

You will probably have to trace/ohm out where each terminal goes to on the 
coil.  Hopefully, the above chart will give you an idea what to look 
for.  It is possible that it has seven terminals by default, but not all of 
them are actually connected too.

Cheers,

         Terry


At 02:27 PM 10/3/2004, you wrote:
>Hello all,
>
>This is my first time attempting to post anything, so please bare with 
>me.  At any rate, I am in the process of building my first coil and at a 
>recent Ham-fest, I picked up a variac that looked as though it was in 
>excellent shape (good brush, easy rotation, no burnt windings).  Anyways, 
>I have come to find out that I cannot find any litterature anywhere about 
>the terminal assignments for this thing(except for the brush on T-3).  It 
>is a Staco Adjust-a-Volt with the following characteristics:
>Type: 500 BU
>Rated Current:  7.5A
>Input V: 120V 50/60Hz
>Output V: 0-140V
>Additionally, it has 7 terminals to choose from(That is the real source 
>for my confusion).
>
>The first time I hooked it up with the common on T-4 and hot on T-5, I got 
>140V at max scale between common and brush.
>The second time, I used T-4 for common and T-6 for hot and tripped the 
>circuit breaker.
>Then, I changed it back to T-4 and T-5 and was checking the current into 
>it with my meter in series.  It was not drawing much current in a steady 
>state senario, but once I hit the terminal and backed of and hit it again 
>and a nice spark roasted my fine point of my meter into a flat.  Is this 
>the effect of "inrush current?" (BTW, it was still operating at the 
>prescribed 140V out at max on the scale.)
>Also, if anybody knows anything about this crazy variac.  How do I hook it 
>up to get 120V max output for my NST?
>I cannot find anything from Staco's site that says that this thing ever 
>existed, so any help will be greatly appreciated.
>
>Thanks,
>Andy