Tony Goetz wrote:
.......
>
>This is the circuit I'm using: <A
>HREF="http://www.cs.uwa.edu.au/~mafm/robot/blanch-h-bridge.html">MOSFET
>H-Bridge Schematic & Theory of Operation</A>
>


Tony, I didn't follow all responses of this thread, but have a
couple of comments. First, Blanchard's ckt has been modifed and
re-modifed a couple of times - see here:

http://www.cadvision.com/blanchas/hexfet/h-bridge.htm
http://www.cadvision.com/blanchas/hexfet/h-bridge.gif
http://www.armory.com/~rstevew/Public/H-Bridges/Blanchard/nch-brdg.htm

Secondly, some ckts to be found use all n-MOSFETs and some ckts use
both p- and n- types. You have to be very careful which one is above
and which is below in the h-bridge.

Third, it is easy to swap source and drain terminals when inserting
- esp for the upper device. Double check this last aspect. Also, I
am not sure all schematics draw this correctly.

I also have some other H-bridge links on my robotics page:

http://www.oricomtech.com/robolnk2.htm#Mot2

hope this helps,
- dan michaels
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