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Re: [TCML] sstc
Hi Chris,
I'm using 4 TC4420 mosfet drivers (two for each GDT), running from 12 volts
(I will boost that to 20V), with 1:1 gate drive transformers and tranzorbs
(20v) on the mosfet side of the gate drive transformer and some schottkeys
on the output of the GDT to clamp it to the supply rails, this seemed to be
working as the schotkeys did get a little warm and I haven't killed a single
driver (where as before with out them I killed quite a few!)
But what I found unusual was that two only mosfets were getting warm but the
other two would stay cold. I thought that maybe i left one GDT disconnected
or something but I double checked everything and it was all good. So i
suppose the irf740 is just a bit under rated?
Yes i have had a look at Ritchie's excellent website, it was actually what
inspired me to build my own!
I have some MUR1800's across the mosfets. The data sheet says max of 100ns
recovery time, would this be fast enough?
In addition to all this I was using an antenna feedback scheme, but it would
sometimes only oscillate fairly erratically, especially on very large duty
cycles, so for my next attempt, I am thinking about secondary base current
feed back. What would be the best way to go about this? I was thinking of a
current transformer arrangement, with a ferrite core like those in the GDT,
what would be the best approach?
Thanks for the info,
cheers
Jesse Frost
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