Abstract: A control system for an angiographic injector which precisely regulates the speed of a motor used to expel contrast media from a syringe. The control system is centered around a microprocessor which receives commands from the operator via a keyboard, and then regulates the speed of the motor by supplying drive command pulses to a circuit which integrates the difference in frequency between the command pulses and another pulse train whose frequency is proportional to actual motor speed. The control system also includes a velocity loop which uses the motor back EMF to supply an analog voltage also proportional to motor speed to a difference amplifier in a conventional velocity loop. The system is a dual loop controller where the second loop provides approximate speed control, while the first loop provides a "velocity correction" voltage required to bring the system to zero steady state speed error.