> > http://www.bobblick.com/bob/projects/hbridge/index.html
>
> The thing that concerned my about that circuit is the 4V voltage drop.
>
> I was hoping to get a circuit that has a minimal drop of the supply voltage
> because I'm driving 12V motors with a 12V battery.

Hi Byron,

It only drops 4 volts when it's at full current. At lower current your
drop is more like 2 volts. If you think about how a DC motor works, you'll
see that there is no way to operate a 12 volt motor with 12 volts and 5
amps at high speed. If you had a motor like this, it would draw much more
than 5 amps at low speed, and destroy the H-bridge. At low speeds, it
doesn't matter how much voltage gets to the motor, since you are torqueing
around and the current is what matters. So in fact, dropping 4 volts at
full current makes the bridge a little sloppy, but limits the current.

Be sure to heatsink it well, though :-)

It is easy enough to build one and test it, you really should since it
does work pretty well and is tougher than a mosfet one. I would not
consider building a mosfet hbridge for use with motors unless there was
fast current limiting.

Cheerful regards,
Bob