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Re: rectifier stack experts?



Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

> I am not trying to be confrontational, but I don't think your statement is
> correct.  Maybe you can clarify what you mean, in case I misunderstood
you.
>
> The way I see it, if you draw out a full bridge, each diode in the bridge
> being rated accordingly for 1 volt (with a small margin for error, so say
> 1.1 volts) and create a scenario where the cap is fully charged to 1 volt,
> and the AC signal is at a peak value (which is also +1 and -1, or vise
> versa) each diode potentially sees +2 or -2 volts as a maximum, and
> breakdown will occur.  The only place where you are protected by 2 diodes
in
> series, is across the capacitor terminals, which also appears at the +
and -
> terminals of the bridge.  This is not where the problem occurs.  The
problem
> occurs between a polarized terminal and a non-polarized terminal of the
> bridge.


>>>>  Yes, you have a single diode between the polarized and nonpol terminal
at one side of the cap, but you also have a diode on the other side as
well...

 Am I making any sense, or do I have this all wrong?
>

> >Bear in mind, though, that if you are using a bridge rectifier, you have
> >two diodes in series, so each diode really only needs to be rated for
Vpeak
> >(plus margin!).
>


In all situations, don't you have the loop: transformer winding, diode,
capacitor, diode; winding, diode...

the cap, at most is Vpeak... the winding is at most Vpeak, so 2 Vpeak total,
2 diodes in series...

I drew a little diagram, and I couldn't get any loops around which you would
sum 2 Vpeak AND have only 1 diode....  There are 4 possible loops with 3
components in series (2 with cap and 2 diodes, and 2 with transformer and 2
diodes), and 2 possible loops with 4 components in series.

I think I covered them all...