Abstract: Ultrasonic pest control apparatus comprising an elongated housing having opposite ends, a sound generator carried by the housing adjacent one end thereof and including at least one transducer for providing output sound waves when driven by an electrical signal, the sound waves being directed outwardly from the end of the housing and having a frequency normally inaudible to humans and intolerable by pests such as rodents and the like, and an electrical connector element at the other end of the housing adapted to be inserted manually into a standard electrical outlet receptacle commonly found in buildings and the like. The connector can be of the prong type or of the threaded type commonly found on the base of electric lamps. The transducer preferably is driven in a manner such that the generated sound waves are a composite output in the form of a random pattern of harmonies.

Abstract: Ultrasonic pest control apparatus comprising a pair of transducers, one in the form of a ring and the other in the form of a disc positioned within the ring, carried by a housing, a pair of oscillators operatively connected to the transducers, a timer controlling the oscillators, and a reflector extending from the housing. The oscillators apply to the transducers electrical signals having frequencies different from the natural frequencies of the transducers, and the timer controls the oscillator duty cycle. The generated sound waves are a composite output in the form of a random pattern of harmonics in the ultrasonic frequency range noramlly inaudible to humans and intolerable by pests such as rodents. A system includes a pair of units in opposed alignment whereby sound waves of one unit work against sound waves of the other. A gas-tight sealing arrangement associated with transducer and housing permits safe operation in explosive atmospheres.