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Re: strange variac
Original poster: "Dr. Resonance" <resonance-at-jvlnet-dot-com>
Some variacs vary, but usually the 120 VAC input is placed across terminals
1 & 4. Output is terminal 3. Check with voltmeter between 3 and 4 to
determine correct 120 VAC output. Sometimes the hot is on 4 and common
(neutral) is 1, and other times the hot and netrual are reversed, ie, hot on
1 and common on 4.
> 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,
> have come to find out that I cannot find any litterature anywhere about
> 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
> 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
> with my meter in series. It was not drawing much current in a steady
> 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.