On Tue, 19 May 2015 14:52:24 -0700, you wrote: >On Tue, May 19, 2015 at 2:28 PM, James Cameron wrote: > >> Specs for voltage say 120 AC/DC. >> Might every second peak of the 240V AC waveform be delivered? >> > >That's an interesting thought and spurs the creative juice, but >unfortunately, no. > >This equipment gets mounted in various different industrial settings where >the system control bus can be 120V, 240V AC or 48V, 125V, 250V DC. >So far we've pushed the relatively few 48V DC customers to rewire their >systems for 120V AC. For the customers that have 250V DC, that's not reall= y >a favorable option for them. The DC customers usually derive the control >bus power from a battery bank that fills a whole room. The suggestion of >changing to something thats not battery backed is not usually well receive= d. >From 240VDC, maybe a simple PWM chopper would do the trick - MOSFET or IGB= T I wonder if you could do it with an off-the-shelf (non zero-crossing) SSR. Another off-the-shelf option may be two 240-to-48VDC switchmode PSUs (trimm= ed up a bit to get towards 120VDC) with the outputs in series. This should cover both AC and= DC 250V users. Most SMPSs will work on DC input but probably best to use ones that are act= ually specced for it - ones with clever PFC might have issues ISTR PULS have DC specs on some of their range.=20 --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .