Abstract: An ultra-sonic pest control apparatus includes a tone generator for generating an output frequency as a function of applied voltage, a transducer electrically connected to the output of the tone generator for delivering ultra-sonic sound, and a generator for generating a periodically repeating sawtooth waveform. A gating oscillator connected to the tone generator and generator emits a frequency sweep responsive to each sawtooth pattern of the sawtooth waveforms and uniformly chops a portion of each frequency sweep and passes the chopped frequency sweeps at predetermined, uniform, timed intervals to the transducer.