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Re: Solid State - progress.



I am measuring a 1kw ferrite core right now.  When both E sections are 
put together I get about 5.5cm x 5.5cm x 2cm.  You can easily put 
several side by side for an even bigger core 5.5x5.5x4 cm.  You can 
get one easily out of an old mainframe computer supply 5v -at- 200 amps 
or whatever. Those are cheap nowadays.  You can tell that the core is 
of the right material if it has appreciable conduction when ohmmeter 
probe tips touch it (eg. this core has ~10kohms at probe distance of 
about 1/4in).  Some cores are used only as filter chokes and have very 
high resistance- not suitable for transformers at 100khz or so.

For really critical applications, the subject of core loss and power 
handling is very complicated; and in the end you really need to 
consult the manufacturer datasheets for loss at any particular 
frequency.  The book that I believe explains magnetics and the 
electronics of switching power supplies in the easiest to understand 
fashion is "High Frequency Switching Power Supplies" by George 
Chryssis.  The Motorola MOSFET databook and the Unitrode IC databook 
also are packed with useful info.

Also, if you see any IRF740 mosfets, those are the most suitable for 
these applications (I've seen several detailed analyses where they had 
lowest lost for high-freq half-bridge or full bridge operation). 

I promise that I will start working on the schematic today. I'm sorry 
that I haven't started it earlier, but I had to put new door on my 
Alfa and finally got everything together, cleaned, and waxed and ready 
for the next auto disaster.

Rob.