Re: rectifier stack experts?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Craig Fuller by way of Terry Fritz <twftesla-at-qwest-dot-net>" <cbfull-at-hotmail-dot-com>




>Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-qwest-dot-net>" 
><m.j.watts-at-massey.ac.nz>
>
>On 22 Oct 2002, at 18:44, Tesla list wrote:
>
> > Original poster: "Craig Fuller by way of Terry Fritz
><twftesla-at-qwest-dot-net>" <cbfull-at-hotmail-dot-com>

>What do you mean by "potentially"? Consider one half cycle and
>replace each conducting diode by a piece of wire in your diagram.
>What you actually get is two reverse-biased diodes in parallel across
>the transformer/capacitor which are also essentially in parallel. In
>a f.w. bridge configuration, Vtransformer and Vcapacitor never appear
>added in series across anything. Very different from centre-tapped
>f.w. or voltage-doubling half wave configurations I might add.
>
>Regards,
>Malcolm

I like your simplification of replacing forward biased diodes with wires.  
It helps to see what's happening more clearly.  I probably could have found 
a better word to use than "potentially".  The engineering book I was reading 
did not go into much detail as to why the bridge must be rated Vpeak * 2.  I 
assumed it was because the diodes and capacitor tend to act together in a 
fashion similar to how a cascade multiplier works to increase voltage.  
Another reason I didn't question it was that I once rectified the output of 
a 15kV NST with a full bridge rated for 25kV, 1A continuous, which worked 
fine until I added a capacitor.  After that, it lasted about two minutes.  
Maybe I will do some more research to see if I can find something that goes 
into more detail.  Maybe you could too and post your findings.  I think it 
would help everyone of us tinkerers to know that we are needlessly 
destroying our diodes when it could be avoided.