[ARC5] Cool New DC-DC Converter

[Brian Clarke]

Totally irrelevant, Dennis. And spot-on, Peter.
In multi-output mass-produced switch mode power supplies, eg, for
PCs, you can bet that the accountant designers have ensured that only
just enough power is available at each output, independent of the
input transformer design. So the fantasy that outputs can do a dosy-do
while the loads on each change, is just that - pure fantasy.
73 de Brian, VK2GCE.

On Fri, 16 Mar 2018 12:39:39 -0400, Peter said:

 It’s a bit different with switchers, a lot depends on the design.
 The input section has a power limitation and each output section has
limitations. In a very simple design the output section limitations
may be the components, such as diodes, acting like fuses. A lack of
load on one section could well allow a lot more output on another
section before the input section reaches its limit. However, in this
case, filaments may take long enough when cold to cause a diode
failure. You may need to replace the low voltage section diode with a
beefier version to handle the warm-up overload. 

A more sophisticated power supply would have overload protection on
each output and may limit current or even shut down the supply trying
to light filaments. 

Peter

On Mar 16, 2018, at 12:19 PM, Dennis Monticelli
<dennis.monticelli at gmail.com [1]> wrote:

Brian,

I think there is a misunderstanding.  I think Scott was only trying
to point out that the primary winding and mag core are shared by all
secondary loads.  You can only get so many VA out of a transformer
before hitting the limitations of primary winding resistance and/or
core saturation.

Dennis AE6C

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