22 Sep
2005
22 Sep
'05
1:53 a.m.
A crude method is to find three biggish AC power
transformers all the
same. Hook all three secondaries together in parallel, then use one
of the primaries as the primary and hook the other two secondaries
series-aiding to make the 220 volt 'secondary.'
Just watch your phasing; get the leads swapped to one of the "other
two" transformers and you'll get (nominal) zero voltage instead of
double voltage.
Indeed, you can do something autotransformerish with only two
transformers:
---------------------.
IN |
--------+------------|-------------------------------
| +----+ OUT
| | | +-------------
| | | |
|_()()()()()_| |_()()()()()_|
_==========_ _==========_
| ()()()()() | | ()()()()() |
| | | |
+------------|----+ |
+-----------------+
Of course, the three-transformer version produces double voltage that's
isolated from the input, whereas the above doesn't. Also, you still
have to watch the phasing; get a winding's leads swapped and you get
zero voltage instead of doubled voltage.
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