-=> Quoting Roy McNeill to Chris Burgess <=-

Hello Roy,

 RM> The only ways I can see of faking a 240V sinewave are (a) synth it
 RM> with fast pwm, as above, (b) do a squarewave and filter it at hi
 RM> power with caps and big fat heavy expensive inductors, (c) synth it
 RM> as in (a) and filter the output as in (b), and (d) drive the
 RM> transformer with a linear amp, and waste a bit of the 240 output to
 RM> drive its cooling fans.

 The way they usually do it, is convert the incoming DC to 340v, and use a
push-pull arangement with PWM to simulate a sine wave.  Then filter it anyway,
using more or less standard mains filters.  You will get a small amount of
switching noise in the mains, but it mostly depends on how quick the PWM was.

John Tserkezis, Sydney, Oz. Fidonet: 3:712/610  Internet: jt{at}suburbia.com.au

... Make it idiot proof and someone will make a better idiot.
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