Phacoemulsification apparatus includes a phacoemulsification handpiece havinga needle and an electrical circuitry for ultrasonic vibrating the needle. Apower source provides pulsed electrical power to the handpiece electricalcircuitry and an input is provided for enabling a surgeon to select anamplitude of dislighted pulses and a pulse width. A control system and pulseduty cycle is provided for controlling the off duty cycle to insure heatdissipation before a subsequent pulse is activated, including a foot pedalswitch.
