I want to drive a 42v dc motor with an L298 motor driver from Solarbotics. http://www.solarbotics.com/products/k_cmd/ The datasheet states the chip will take up to 50v. Does this mean the motor can be controlled by Arduino and the driver board without a Mosfet to protect Arduino?
yes you don't need any Mosfets! Just add the required heatsink, decoupling capacitors and fast-recovery diodes around the motor to protect L298 from harmful spikes. The basic circuit illustrated in the data sheet works fine with Arduino. Just connect the logic pins (enable, forward, reverse) plus logic supply to the Arduino one, since it works at 5V. Separate power supply for the motor. You can even do PWM with the L298! I didn't find it hard to work at all as Solarbotics says, even if I'm an electronic n00bie!!