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.
