[Amps] Equalising resistors with HV diodes

[Radio WC6W]

On Tue, 21 Sep 2004 01:16:48 -0400 bb <bbolin at yadtel.net> writes:
> 
> >73,
> >    Marv  WC6W
> >
> >P.S. -- Here are two more good references on the topic:
> >
> >Rca Silicon Power Circuits Manual, SB-50, 1967, pp. 23-26
> >
> >International Rectifier Superpower High Voltage Rectifier Columns,
> >SR-370-A, 1960, p. 3
> 
> Marv,
> First I don't have a dog in this pit.
> But I do have one question.
> So far all the books you listed where printed before 1967
> and things change in almost 40 years.
> Do you use or have any references newer on this subject?

Hi Bennie,
   Well, if one is designing with 40 year old parts using 40 year old
techniques then the old science is applicable.

   Regarding the literature, I believe that you'll find, as with most
scientific topics, most research & publication is done when the field is
newest and then absent some major breakthrough falls silent.    It is
much the same with any other technology.  If you seek good reference
material on inductors, then you must have the literature of the 1930's or
similarly with tubes, the 1950's.     

  The books I reference, were written when silicon diodes were coming
into their own in electronics applications and are therefore the most
cogent.   Just try to find the detailed specs on any old diode in a
modern book.   None of the companies that currently manufacture diodes as
a mature product are going to publish any.

  Did you ever find any info on series operation in the (1993) reference
that you previously listed?

                 Motorola Rectifier Applications Handbook
                http://www.onsemi.com/pub/Collateral/HB214-D.PDF

  Things do change.

  Modern HV diode stacks are manufactured with matched die stacked in a
single package... without equalization components nor discussion.

  Absent that sophistication a, non-amateur, manufacturer would series
(avalanche rated) 1N5554's in lieu of 1N5408's.   Yes, they do cost a bit
more.   
     
> In past projects and travels I have not had any problems in not using
> equalizing resistors as long as you follow the rules.

   What are those rules?  Are they the same as for playing the lottery? 
:-)

    It did work for Heathkit except, for those occasional instances of:
"All my diodes exploded for no reason...".

>   The one thing that gets me is how big this debate is,  just
> like the one you reference 5years ago on this list.

    It is the fine line between anecdotal experience and scientific
experiment.

> This is as big as tube audio debate.

    That's a wider gulf... perhaps springing from... upbringing?   If one
had always listened to tube "sweetened" output then, perchance the same
material undistorted might just sound wrong!

    If tube folk really craved low distortion then, they'd build with
4CX600J's instead of 833A's.  Perhaps, it is more about appearance than
function?

> All I can say is WOW and never post any questions on diodes.

   Every 5 years a little rectification* is good for the diode.

> Bennie
> 

73 & Good morning,
    Marv  WC6W


* A note for non-native English readers of this list, the traditional
non-electronic definition is used here.   







#

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