DESIGN, CONSTRUCTION AND DETERMINATION OF FREQUENCY SPECTRUM OF ELECTRONIC RODENT REPELLENT SYSTEM

Abstract

This research work focused on design, construction and determination of frequency spectrum of electronic rodent repellent system. It was initiated due to the fact rodents cause significant economical losses by gnawing, feeding and spoiling cereal crops, stored food and human properties. Rodent damages could be reduced by scaring them from undesired area. So far, different techniques have been employed to scare away rodents. Then, this work introduced an electronic device that scare rodents from home, office, field etc. Hence, the device was constructed using IC 555 timer in astable mode that operates as an oscillator. The oscillator was designed to generate a signal that match with the hearing range frequency of the rodent.The frequency ranges (33.72-44.04) kHz of the signal is controlled by a variable resistor. The weak signal generated at pin 3 of IC 555 timer is amplified by amplifiers circuit designed using the combination of npn and pnp transistors. The schematic diagram of the designed circuit and its simulation were facilitated using PSPICE circuit simulator software estimating the values of circuit elements to match the required frequency range. Based on the results of simulation and paper to pencil analysis the designed circuit elements were identified, built on a breadboard and tested for suitability using DMM and CRO. The device built on the breadboard generated sound of multiple frequencies of oscillations which was inaudible to human while it was irritating and scaring rodents away. The generated sound was captured and analyzed using code developed on MatLab platform to ascertain the frequency match in the required range. The results of the analysis of the recorded sound were presented in three different plots. Namely: time waveform, frequency spectrum and power spectral density. The frequency spectrum of the signal (31-40) kHz matched the measured frequency range. This was accompanied by the construction of the accepted circuit soldered on a strip board encapsulated by wood and plastic made case.