Subject: converting ac welder

From: [email-masked]
Date: Sun, 28 May 95 01:09:16 EST

-=> Quoting Internet: Kleong

 IK> I can't remember my electronics very well, but would
 IK> putting two or more  car alternator diodes in parallel
 IK> work to beef up the current capacity,  or would the
 IK> diodes have to be perfectly balanced (in terms of
 IK> resistance) so as more current wouldn't go through one
 IK> diode, frying it,  and then frying the remaining diodes
 IK> in order?  Would such a system be  inherently stable, ie.
 IK> the diode with the lowest resistance in forward  mode,
 IK> take the most current, heat up, and in doing so increase
 IK> its  resistance so that the system is self balancing, or
 IK> would it self  destruct by lowering its resistance as it
 IK> heated up?

Thats essentially correct. The diodes will not be identical,
current flow in each will differ, and a cascade failure will
probably result.  Balancing circuitry at that current level is
probably impractical.

Very large silicon diodes >200amps are available from
electronics suppliers, but are not cheap.  I found some at an
electronics fleamarket several years ago.

Regards,
Brad Chaucer

... Dime(n): a dollar with all the taxes taken out.
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