Carl, I have used 1000s of these and center red goes to center black for 220 V and use the other red and black as input. Black to black and red to red and this is the 120 input. I have found these to be very good transformers, I have been using these for several years. Derward Myrick ----- Original Message ----- From: "Carl Denk" To: "Microcontroller discussion list - Public." Sent: Monday, July 13, 2009 6:12 PM Subject: Re: [EE] Transformer wiring help >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. >> > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist