Hi Jay et al., I've had a look at the .pdf's that you suggested - interesting stuff! Unfortunately just as it begins to get really interesting it looks as though the pages are missing. The bits that are most relevant to me, 'B-series power supply', are listed in the index .pdf as being at the end of section 9 but the scans of these pages haven't been published. Does anyone have the relevant pages? Looks like section 9, page 132 and following... Cheers to all Peter Brown