Re: Converting diodes to resistors

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

Original poster: "Daniel Barrett by way of Terry Fritz <teslalist-at-qwest-dot-net>" <dbarrett1-at-austin.rr-dot-com>

     Heya!
     The diodes are highly capacitive, so the RF just caused excessive
current flow- the diodes can only stand a few microamps. Try to use (very)
fast recovery diodes for this. I have yet to cook a UF4007, but have burned
up hundreds of 1N4007s...
db

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Sunday, June 22, 2003 12:55 PM
Subject: Converting diodes to resistors


 > Original poster: "S & J Young by way of Terry Fritz <teslalist-at-qwest-dot-net>"
<youngs-at-konnections-dot-net>
 >
 > Semiconductor failure experts,
 >
 > I fried (over easy) a string of  15 1N5408s in my DC resonant charger
power
 > supply.  Usually I have the spark gap across the supply & resonant choke
and
 > the cap in series with the primary.  But I noticed in Richie Burnett's
site
 > he showed the cap across the charging power supply and the gap in series
 > with the primary.  So I tried it.  BIG MISTAKE!  The RF caused a smoky and
 > stinky voltage breakdown in one of the MOTs I used for the charging
 > inductor.  The RF also wiped out a diode string.
 >
 > Question:  The diodes all still have the usual forward characteristics,
but
 > the reverse resistance on all of them has gone from higher than 200
megohms
 > when they are good, to around 12K.  They vary from 5 K to 20 K.  So, just
 > curious, what did the RF do to the diode junctions to make them act like
 > resistors?
 >
 > --Steve Y.
 >
 >