Abstract: A control circuit for a pulse width modulation (PWM) driven electric motor is provided for operating a fan or motor at a full duty cycle in the event that the PWM input signal should malfunction or fail. The control circuit includes a pulse width modulation (PWM) source having an output; a switch having a control and being coupled between a voltage source and the motor; a capacitor having an input coupled to the PWM output and an output coupled to the switch control, and a diode coupled between the PWM output and the switch control for maintaining the output of the capacitor at a predetermined minimum voltage level. In response to a substantially direct voltage level at the PWM output indicative of a failure of the PWM source, the capacitor maintains at its output a voltage level sufficient to cause the switch control to connect the voltage source to an input of the electric motor and drive the electric motor at a full duty-cycle. The diode provides d.c.