PEST MANAGEMENT SYSTEM USING ULTRASOUND PROJECT INDEX: PRJ 080 EDWIN NYAKUNDI MOKAYA F17/1766/2006 SUPERVISOR: DR. G. KAMUCHA EXAMINER: DR. V.K. ODUOL DATE: 25 TH MAY, 2011
OBJECTIVE To design and implement an ultrasound based system that will repel pests such as mice and insects.
PEST MANAGEMENT METHODS Physical Pest Management- Is the physical removal of pests from their location. Bio-Rational Pest Management-Two types. Use of living organisms "Beneficials" that can kill the pest. Use of naturally occurring biochemicals that are harmful to the pest yet harmless to other living organisms. Chemical Pest Management- Is the use of chemicals known as pesticides poison pests. Electronic Pest control-use of ultrasound.
Setbacks of Conventional Pest Management Methods Physical methods can only be used in small scale and is labour intensive. Biorational methods are environmentally friendly, but in case of household pests, only the rats and mice can be controlled while insects are left unchecked. Chemical is more effective, it comes with many health hazards as the chemicals might be harmful to unintended organisms, including human beings.
ULTRASOUND PEST MANAGEMENT SYSTEM ULTRASOUND- Is sound with frequency higher than 23kHz (Human hearing range). Pests such as mice and insects have the capacity to hear this sound. A system which produces this sound will repel the pests. Advantages of Ultrasound Pest Management Is non toxic With use of battery power system will be potable Is cheap as does not require replacement
DESIGN OF ULTRASOUND PEST MANAGEMENT SYSTEM System to produce 40kHz, 50kHz, 60kHz, 70kHz and 80kHz signals.
DESIGN OF OSCILLATOR An oscillator is a circuit that produces a repetitive or alternating electric waveform. An oscillator circuit could be made using individual components (Armstrong oscillator, Hartley circuit, Colpitts circuit and Clapp circuit) or IC. Advantages of IC implementation of oscillator circuit: Compactness High speed Low power requirement Reliability 555-timer was chosen.
OSCILLATOR CIRCUIT DESIGN
OSCILLATOR DESIGN ANALYSIS Capacitor charges between 1/3Vcc and 2/3Vcc. Equations are: Capacitor C RA (ohms) RB (ohms) Calculated Frequency Design Frequency 1nF 18k 6k 40 khz 41.6 khz 1nF 14.4k 6k 50 khz 49.5 khz 1nF 12k 6k 60 khz 61.3 khz 1nF 10.3k 6k 70 khz 71.3kHz 1nF 9k 6k 80 khz 83.5 khz
CIRCUIT FLOW DIAGRAM
CLOCK GENERATOR DESIGN R1 C1 Calculated Output Frequency Designed Output Frequency 10k 1µF 71.63Hz 72.1Hz 50k 1µF 14.33Hz 13.8Hz 100k 1µF 7.16Hz 7.0Hz 200k 1µF 3.58Hz 3.42Hz 300k 1µF 2.39Hz 2.4Hz 400k 1µF 1.79Hz 1.63Hz Clock generator 500k 1µF 1.43Hz 1.5Hz 1M 1µF 0.72Hz 0.7Hz A 1M ohms resistor and 1uF capacitor were used. Simulated clock pulse was 0.7Hz. Therefore oscillator frequency would change every 1/0.7=1.4 sec
COMPLETE DESIGNED CIRCUIT Decade counter used to change value of RA. It was clocked by the low frequency 555-timer oscillator
SOLDERED CIRCUIT
Complete Circuit Output waveforms Vo=11.36V Ro=4ohms Io = Vo /R=11.36/4=2.84A Power= VoxIo =11.48X2.87=32.26Watts Frequency of Vo changed approximately every 1s.
PRACTICAL OSCILLATOR CIRCUIT Close valued resistors were used instead of the calculated and simulated resistors. These together with a 1.12nF capacitor and 5.66k (ohms) resistor for RB were able to achieve frequencies close to required values. Capacitor C RA (ohms) RB (ohms) Required Frequency Actual achieved Frequency 1.12nF 17.88k 5.66k 40kHz 38.9kHz 1.12nF 15.00k 5.66k 50kHz 47.8kHz 1.12nF 12.02k 5.66k 60kHz 59.7kHz 1.12nF 9.95k 5.66k 70kHz 68.3kHz 1.12nF 8.17k 5.66k 80kHz 79.2kHz
CONNECTED CIRCUIT AND OSCILLOSCOPE RESULTS
CONCLUSION The design and implementation of the ultrasound pest management system was done successfully. Output frequencies of 40kHz, 50kHz, 60kHz, 70kHz and 80kHz were produced, which are in the ultrasound range. The output signal was found to be of about 32 watts when connected to a 4 ohms piezo tweeter. A super tweeter with a frequency response of up to 80kHz was not obtained thus demonstration to repel pests was not carried out.
Recommendation for further work The development of cheap super tweeters with frequency response of up to 80kHz. Study to be carried out on the effect of ultrasound on domestic animals with wide hearing ranges like dogs.
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