Re: lucky MOSFET find

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

Original poster: "Gavin Dingley" <gdingley-at-ukf-dot-net> 

Hi Finn,
if those MOSFETs have gone, there will be short circuits between any of the
legs, you should find open circuit between all the connections. If you have
a diode tester on your DVM, you should find about 0.4V across the drain and
source. Of course the gate to either the drain or source should be
practically infinite. To be honest I randomly probe around a MOSFET looking
for obvious shorts. Apart from that, plug it in and see what happens, which
is what you have already done. When they go they go dramatically, which is
bad in a working circuit, but convenient for testing.

Cheers,

Gavin


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Thursday, August 21, 2003 7:07 PM
Subject: lucky MOSFET find


 > Original poster: Finn Hammer <f-h-at-c.dk>
 >
 > Gang,
 >
 > Just as the human eyes adjust to the conditions of the available light,
 > they adjust to spot the contour of parts that are needed for current
 > projects.
 > Like today, when I took a stroll on the local scrapyard, and suddenly
 > found myself staring at a heap of IXYS IXTN79N20 MOSFET`s carefully
 > removed from what appears to be working equipment.
 >
 > I grabbed 30 pcs. and wondered if they could be made to do service in an
 > audio modulated SSTC, for example.
 >
 > They don`t appear on http://www.ixys-dot-com
 > but from the type markings they appear to be 79A 200V types.
 > In the unloaded state, the Gate-Source capacitance is 17.7nF, but this
 > might change.
 >
 > How do i test them?
 >
 > I tried hooking one sample up to a motorcycle lead battery, and apply 12
 > volts to the gate, that caused current to flow, so that the isotop
 > casing got hot, didn`t break it.
 >
 > But there has to be a better way, and I don`t want to break my
 > Plasmatronic board by just plugging them in, to see what happens.
 >
 > Cheers, Finn Hammer
 >
 >