artisticforge:
That is what I thought.I found this while doing some research. Most of the circuit is not needed since you have the arduino to generate the necessary PWM signals. The TIP122 & TIP127 transistor is a power Darlington pair. With proper heat sinking they should be able to handle the 90VDC required by the motor. You may still need to provide a buffer IC for the PWM Signal from the arduino to the TIP122 & TIP127 transistors.
How to Build a High Torque DC Motor Speed Controller Circuit
This is awesome! Thanks for your help!