An ultrasonic dental scaler automatically supplies a frequency to match a handpiece connecting thereto. A handpiece connector includes one or more passive elements, which affect the resonant frequency produced by the generator. Multiple handpieces, each operating at a different resonant frequency, may thus be used with the same ultrasonic generator. The ultrasonic dental scaler also supports two footswitches. One footswitch includes a foot-controlled power level adjuster. When connected, the footswitch automatically disables the manual power adjuster. Another on-off footswitch includes no power adjustment mechanism. When connected, the manual power adjustment feature of the generator is maintained. Orders for different handpiece frequencies and footswitch types can thus be filled with an inventory of one generator model.