Unlike AC motors, DC motors provide instant response, make no sound, and provide consistent operations. Two common types are used in sewing machines: drive motors and pulse motors. The drive motors function like the traditional AC motors, but are smaller and more dependable. Pulse motors are triggered by electronic signal telling them to turn on or off. Like the name implies, these motors may only turn for a moment and then shut off. On board computers enable the sewing machine to control the DC motors for improved performance and convenience.