>From: Ed Gould <edgould1948 at comcast.net> >I am *NOT* an expert in this area... but I think the main issue is 50 >vs 60 cycles. The 110 and 220 is easily done (like you said) a flip >of a switch (provided there is on). 50/60Hz is no problem. For supplies you may find in the real world, DC is out, as is the 400Hz that was (still is?) used in aircraft workings (not what you see as a passenger). Less than I guess 40Hz would get less efficient as in the ones I've seen inside of the input in via a large capacitor. David -- David Ledger - Freelance Unix Sysadmin in the UK. HP-UX specialist of hpUG technical user group (www.hpug.org.uk) david.ledger at ivdcs.co.uk www.ivdcs.co.uk