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The flexible-input, desired-output (FIDO) motor controller is a robust wireless motor controller specifically designed for engineering design classes where students design and build radio-controlled devices that are typically featured in an end-of-semester celebration or competition. The controller receives bidirectional control signals from a standard 72-MHz band hobby radio transmitter and proportionally drives four motors with up to 3 A of current in each. The controller is designed to accommodate changes to the battery voltage as well as motors with different voltage ratings. It is also designed to be built easily by teaching assistants and can be reused year after year. These capabilities are designed to lower the cost of running this type of class and reduce the organizational work load required of the instructors. Specifically, this motor controller enables the use of commercial cordless drill batteries as inexpensive, portable sources to power motors at a wide range of voltage ratings. The drills are also used during the class as construction tools and can be used by the student after the class. The FIDO motor controller has been successfully tested in the 2.007-Design and Manufacturing classes at the Massachusetts Institute of Technology (MIT) Cambridge, and its utility and acceptance are confirmed by a class survey. Detailed circuit schematics are provided in the Appendix.