I found this circuit on the web.
http://www.mcmanis.com/chuck/robotics/tutorial/h-bridge/bjt-circuit.html

Seems to work great on 12 volts or so. I used a 1.5 ohm
resistor to simulate the coil.  Works to 125 PPS
or 7500 RPM.

The trick is to use opto isolators to trigger the FET's.

I'll know  more when I get the 300 volt power supplies.


Next step is build another one and hook them both
to the same resistor.

Basically what this does is substitute for the half bridge
driver chip.

Paul Lamar

The Rotary Engine NewsLetter. Powered by Linux.
ACRE NL web site. http://www.rotaryeng.net
Youtube key word PaulLamar2
Copyright 1998-2010 All world wide rights reserved.