Motor Control Applications | Mouser Motor Control applications, design and motor control products are available at Mouser, a global authorized distributor of semiconductors and electronic components. Skip to Speed Control of DC Motor - ELECTRICAL TECHNOLOGY Speed Control of DC Series Motor. Speed control of DC series motor is done by the armature control and field control methods. Armature Resistance control method for DC series motor. In this method, a variable resistor or rheostat connected in series with armature resistor. The circuit diagram of this method is as shown in the below figure.