Development and preliminary testing of an electronic pest repeller with automatic frequency variation

Abstract

This study presents the development and preliminary performance evaluation of an improved electronic pest repeller with automatic frequency variation. The study is aimed at developing a device that is capable of emitting ultrasonic energy of varied frequencies. These frequencies do affect the auditory senses of pests such as rodents, avian and nocturnal insects by making them uncomfortable in their abode. However these frequencies do not affect the hearing ability of man. An Astable Multi-vibrator (AMV), timer NE555 was used to generate the required ultrasonic frequency and automatically varied in five steps by a pulse generating IC (CA3130) and a counter (CD4017). A D-type flip-flop IC (CD4013) was used to obtain a symmetrical output signal which was amplified in push-pull mode by 2-NPN Transistors (BD-139) and 2-PNP transistors (BD140). Five variable resistors (each 100KΩ) were used to control the different frequencies selection. Two transducers (tweeters) were employed to produce an efficient sound generated. The unit was tested with three groups of white foot mice (Peromyscus leucopus) and a female house mouse Mus musculus which all responded positively from a distance of up to fifteen (15) meters from the source. The average designed efficiency was found to be 86.5%. The device can be utilized by both small and large scale farmers for the purpose of repelling pests. The performance of the device could be greatly improved with little modifications, for instance, using microcontrollers and ultrasonic sensors to transmit the ultrasonic sound in a special band of frequency.