I don't have a variac. It is clear on the input side, that the windings 
are in a straight line, just like a center tap, but broken at the 
center. Both windings have black to the left side, and red at the right 
handed side. That makes the outers a black and red, with the center also 
a black and red. For 220 it seems clear that I connect to outer red and 
blacks to the power hot and neutral, and the center red and black to 
each other. For 110, it seems that black and black, and red and red to 
the power hot and neutral. This would go with the common way of doing 
things.

Thanks for the thoughts. If I blow it, no big thing, it was cheap, came 
along for the ride with some things I needed. :)

Olin Lathrop wrote:
> Carl Denk wrote:
>   
>> I got this transformer rated: *Input:* 110/220VAC 60Hz *Outputs:*
>> 24VAC @ 2A (12V-0V-12V) and I'm nut sure how to hook it up.
>>     
>
> With 110V in you put the two primaries in parallel, with 220V you put them
> in series.  In either case be very sure to get the polarities right, else
> poof.  You could try to bring it up slowly from a variac output to make
> sure.
>
>
> ********************************************************************
> Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
> (978) 742-9014.  Gold level PIC consultants since 2000.
>   
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