Hello, Michael, On 1/14/10, Michael Sokolov <msoko...@ivan.harhan.org> wrote: > 1. What is the benefit from having the DC blocking capacitor across the > centre split in the transformer's primary winding? What harm would > there be if someone took that capacitor off the BOM and simply > shorted those pins on the transformer to make the primary winding > effectively non-split?
My guess is that in some cases there may be unintended DC bias which could put the transformer core into non-linear region. I think if DC conductivity is needed it should be provided with another part. > 2. Suppose that I do want my CO-side terminal unit to provide DC power > feed on the line - say, to power a mid-span repeater. Where would I > need to connect my DC power source? Would it need to be connected > across the centre split of the line transformer's primary winding in > parallel with the cap, or would it simply go across the copper pair > instead? As I understand, it should _not_ be connected across the centre split for the same reason (DC current will run through the transformer). > Some of those SDSL transformers (which are all custom parts) were > apparently designed for fairly high DC current, so it seems like > connecting the DC power source (or load) across the centre split is > the way it's done. I have no idea; probably, those transformers could be used for different purposes. Regards, Ineiev _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user