"Michele Ancis" wrote in message =
...
In data Tue, 04 May 2004 15:54:21 GMT, David ha scritto:
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"Michele Ancis" wrote in message =
...
Hi,
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[CUT]
can think of is the voltage on the diode bridge...or across the =
"chopping"
transistor...
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Any suggestions are welcome
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Michele, Many switching supplies use a doubler for 110 operation in =
the
line rectifier circuit. There is usually one wire to disconnect =
which
turns the rectifier into a non doubling full wave bridge. If you can
power it up on 110 and measure the DC feeding the switching =
transformer
primary, and it measures about 300 volts, than you have a doubler =
and it
can be rewired easily for 220 operation.=20
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David
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Thanks David! I had my friend to describe the rectifier and...yes, =
there is
a jumper connecting a common node for two series caps to one output of =
the
bridge..
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+---------+
| |
| / \
| / \
(~) +- -------+------+
| | \ / |
| | \ / --- L
| | | --- C1 O
| | | | A
+---------+---/J\----+ D
| | =20
| --- =20
| --- C2
| |
+---------------+------+
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I've done a simple simulation and this arrangement allows to have =
either a
doubled DC voltage (jumper ON) or a "normal" voltage (jumper OFF).=20
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That was of great help guys thanks a lot!
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M
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email:

Glad to be of help. This how almost all computer power supplies handle =
110/220 operation. It is quite clever actually.
David