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[...] The circuit I used is a standard 4 N channel MOSFETs driven from the output of a CMOS 4011 running at 12 volts, no resistors.
When I fired up the circuit the most voltage I can get across the motor is 8 volts from a 12 volt supply.
The bottom MOSFETs appear to be switching completely on but the top 2, the ones where the drains go to Vcc, are not apparently.
I just assumed the circuit would supply almost 12 v to the motor with 12 volts into the gates. This is the same circuit as in the Robot Bonnazas book. Yet they never highlighted the fact that that circuit would never supply the full 12v to the motor.
So now my wheels are turning alot slower. Since I used a high RPM motor than needed, this may or may not be a problem. Still need to investigate. So I assume the IRF540s are OK, that I would have the same problem with any N channel MOSFET. Maybe if I had built the H bridge which uses P and N channel I wouldn't have this problem.
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