"tony sayer" wrote in message
...
In article , Mortimer
scribeth thus
"greenaum" wrote in message
...
I imagine in your MOSFET case,
either one of them wasn't making proper contact or, more likely, the
FETs were tougher than you thought. Electronics, and power electronics
particularly, can take a lot more than they're rated for, before they
actually blow.

But when they blow, you know about it...

At university we had a project to develop a switched-mode power-supply in
which a thyristor is switched on and off at a constant frequency but with
a
variable mark-to-space ratio to keep the output voltage after smoothing
constant with a varying load.

We were warned that the thyristor that we'd been supplied with was rated
to
carry a certain current, but only when it was being switched and not when
it
was permanently turned on.

It was only a matter of time before one of the teams suffered a loose wire
between the thryristor and the switching circuit while the PSU was
carrying
full load...

Within a matter of about two seconds, there were five distinct sounds: a
cry
of "****!" from the person who had accidentally disconnected the
oscillator,
a yell of "duck!", a scraping of chairs on the floor as everyone took
cover,
a VERY loud bang like a shotgun, and a gasp of "F**k!" as everyone reacted
to the bang.

The end had blown off the thyristor and embedded itself in the ceiling -
thank goodness it went upwards instead of into someone.


Suppose thats what Uni us for, learning what to do when it all goes tits
up..

I was very proud to be a member of the winning team who managed not to blow
their thyristor up and achieved staggeringly high efficiency measurements
(power out/power in) due to a novel design which a mate dreamed up. I've
still got the book that I received as a prize.

Talking of tits, if that thryistor had gone sideways, that's where it might
have ended up - in the Massive Mammaries (TM) of the only woman on the
course. ;-)