Hi Bill. the self destruct action is a dissipation issue. A typical 1000v
3A diode can handle about 2A on a continuous basis and that comes out to
about 1.5 watts (.7V X 2A).
Many of the 1N5408 diodes tested showed avalanche action at about 1400v.
Staying within the 1.5 watt figure, that allows only 1.5 / 1400 = 1.07
milliamps current flow. One would expect long term survival at that
voltage/current/wattage.
A 12 v zener might have a 25 watt rating and that would allow 2.08 amps
that needs derating to about 1A for long term survival.
I am not sure what application a 1.5W 1400v zener would be needed for but
the part is readily available.
73,
Gerald K5GW
In a message dated 9/6/2012 10:09:12 A.M. Central Daylight Time,
dezrat1242@yahoo.com writes:
ORIGINAL MESSAGE:
vOn Thu, 06 Sep 2012 11:55:28 +0100, David wrote:
>To add a spanner into the works regarding the direction of current, I
don't know
>why these things are call zener diodes, since all the high voltage ones
work on
>avalanche breakdown.
>
>Dave, G8WRB
REPLY:
Zener diodes are different from regular diodes because they are designed
to pass
current in the reverse direction and survive. All silicon diodes have a
zener
point where they begin reverse conduction, but unless they are specifically
designed for it, most of them will immediately self-destruct.
More info: http://en.wikipedia.org/wiki/Zener_diode
73, Bill W6WRT
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|