Abstract: A boost circuit is used for power factor correction (PFC). In a low power application, transition mode control is utilized. However, switching frequency varies with different input voltages, and over a wide input voltage range, the switching frequency can become too high to be practical. To address this issue, a boost circuit is provided whose effective inductance changes as a function of input voltage. By changing the inductance, control is exercised over switching frequency.

Abstract: A boost circuit is used for power factor correction (PFC). In a low power application, transition mode control is utilized. However, switching frequency varies with different input voltages, and over a wide input voltage range, the switching frequency can become too high to be practical. To address this issue, a boost circuit is provided whose effective inductance changes as a function of input voltage. By changing the inductance, control is exercised over switching frequency.

Abstract: A windshield wiper system and method includes a dc motor for connection to drive a windshield wiper. A motor current switch controls current through a field winding of the dc motor. First and second speed selection switches are provided for selecting a speed desired for the windshield wiper. Means responsive to actuation of the first speed selection switch operates the motor current switch to control the current through the field winding of the dc motor for a first duty cycle, and means responsive to actuation of the second speed selection switch operates the motor current switch to control the current through the field winding of the dc motor for a second duty cycle different from the first duty cycle. A delay switch is provided, and a motor drive circuit responsive to a first activation of the switch enables the circuit for operating the motor to drive the windshield wiper once.