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Re: Mike Marcum Ferrite Cores

Original poster: Terry Fritz <vardin@xxxxxxxxxxxxxxxxxxxxxxx>

Hi Matt,

At 04:54 AM 10/11/2005, you wrote: 
....... Actually I'm
seriously looking at what Terry's up to right now. You
know, when all this solid state stuff first started I
just thought it was a joke, a new/fun way to blow up
transistors, but the results are looking real now!
The newest design looks so simple that I might even
give it a whirl? Still for the life of Me I can't
figure out what that little 5uF poly cap is doing in
parallel with the C-drive caps's?

---- Matt Cortner ----

The buss caps need to take 100kHz at say 500 amps! Even though there are 20 electrolytics in parallel, electrolytic caps have a fairly high internal resistance and may not like that. The two 2.5uF caps are full super high current pulse caps that are more than happy running very high pulse current. There are also two 20nF ceramic caps too. The 2.5uF and ceramic caps are also very closely directly across the H-bridge where the electrolytics tend to be wired further away. Thus, the very short leads to the H-bridge provide immediate bypassing directly at the H-bridge of the high current pulses.

However, the two caps are expensive and a pain to get. So I hope to reduce them to common DigiKey pulse caps or maybe remove them all together if the electrolytics can be moved in close. But I really don't like the idea of the electrolytics taking all that load since I am beating them up pretty good already.

Cheers,

        Terry