[Amps] OM power power supply design

[Bill, W6WRT]

ORIGINAL MESSAGE:

On Wed, 9 Dec 2009 09:01:14 -0200, Felipe Ceglia <felipeceglia2 at gmail.com>
wrote:

>What would be the drawbacks of copying such a design? Should each of
>the windings deliver the required current or should there be a safe
>margin?

REPLY:

Whenever you put transformer secondaries in series you must be careful not to
exceed the insulation rating between a secondary and the iron core, and also
between a secondary and the AC primary. 

The problem is this: In the circuit shown, the transformer at the "hot" end of
the string has the full DC string of voltages between its secondary and the core
and the AC primary. Each of the transformers down the string also has a
proportionate voltage appearing there. A transformer rated for only 250 V on the
secondary may not have insulation rated for several thousand volts, because in
"normal" use it would never see that much. Check with the transformer
manufacturer. Other than that, the circuit should work fine, except that the
increased number of parts also increases the odds of failure at some time in the
future. 

Make sense?

73, Bill W6WRT