Re:

Hi Matt,

> From: "Matt Shaver" <mshaver@...>
>
> > From: "Joel Jacobs" <jj@...>
> > www.spyparts.com/users/jj/driver.jpg
>
> Wow, nice job!

Thanks!

> Schematic?

Maybe - after it's done.

> Is that a 16CE62x?

Yup, it's a 16C620 - good eye!

> Is this a unipolar driver (Six FETs and six resistors vs. four FETs and

two

> resistors)?

Yes, it's unipoler. I'm using a high side switch to the center tap of each
phase pair for the chopping and the phases are selected by low side fets on
each phase. When a phase fet turns off the other phase winding of the pair
is used as a tertiary <sp> catch winding and the energy stored in the
inductance is returned to the supply through some steering diodes. Very
efficiant.

The resistors you see are current sense. The current is limited to 1v
across the sense resistors so I get 1 amp for each pair installed ( they are
1 ohm ea.) So as you see it there are three paralleled resistors for each
side = 3amps/phase. The two low side fets on each winding pair can share
the same sense resistors since they are never both on at the same time.

Joel