Ultrasonic Pest Repellent

1.    INTRODUCTION

The term “ultrasonic” applied to sound refers to anything above the frequencies of audible sound, and nominally includes anything over 20,000 Hz. Humans can hear sounds from about 16 to 20 kHz. Pests like rat, mice can hear ultrasound, the range of the rats hearing is around 200 Hz to 80 to 90 kHz.

Ultrasonic pest repeller is a high-tech device that transmits high intensity sounds at high frequencies. Sounds at such high frequency are not audible to human beings. The sound generated are ‘fiendish’ in the way that penetrates the pest’s brain and nervous system and causes fear discomfort and creates intolerable environment for different kinds of pests but not audible to human beings and absolutely no side effects.

The major aim of this papper is to effectively design and fabricate an electronic system that will be capable of produce ultrasonic sound when the supply is given. Furthermore this device finds use not only in homes but as a precautionary and protective interface in loading Docks, indoor and semi indoor areas, warehouse, food processing units, factories, restaurants, meat shops, etc and can be used almost everywhere.

A key feature of this device is that it does not cause any irritation to human beings.

           

2.    BLOCK DIAGRAM 

3.    BLOCK DIAGRAM DESCRIPTION

            Block diagram has the following components

3.1 SQUARE  WAVE OSCILLATOR:

            It consists of a IC CA 3130 which functions as an square wave oscillator. It is a free running oscillator.

3.2 DECADE COUNTER:

The IC used here is CD 4017. The circuit of the decade counter is similar to 4 bit ripple counter but with the aid of a logic circuit, the count is limited to 9. As soon as the output sequence 1010 occurs output of NAND gate becomes 0 and it resets the flip flops. Counting starts again from 0.

3.3 AMPLIFIER CIRCUIT:

            The IC used is 555 timer IC. An amplifier is an electronic circuit that is capable of amplifying signals.

3.4 D FLIP FLOP:

            The IC used is CD4013. D flip flop is obtained by short circuiting the S and R input of the SR flip flop. This flip flop is also called as Latch flip flop. It has only one input referred to as D input or data input.

3.5 PUSH-PULL AMPLIFIER:

            The name push pull comes from the fact that one transistor drive current through the load in one direction (pushing) while the other transistor drives current in opposite direction (pulling). This type of amplifiers do not need input transformer for phase splitting. Thus cost and bulkiness of the circuit is reduced.

3.6 PIEZO TWEETER:

            A piezo tweeter contains a piezoelectric crystal coupled to mechanical diaphragm. An audio signal is applied to the crystal, which responds by flexing in proportion to the voltage applied across the crystals surfaces, thus converting electrical energy to mechanical energy. This conversion is the basic for ultrasonic testing. The active element is the heart of the transducer(a piece of polarized material with electrodes attached to two of its opposite faces) converts electrical energy to acoustics energy and vice versa.

4.    CIRCUIT DIAGRAM

5. CIRCUIT DIAGRAM DESCRIPTION

This circuit starts to operate as soon as the power supply is on.  In the circuit given there are different stages. The first one is the square wave oscillator stage.

            In square wave oscillator the circuit generates square wave signals, and the output from this stage is given as the input to the next stage ie the decade counter. Here the square wave oscillator produces an output of 1 KHz. Here the IC used is an IC CA3130.

            The next stage is the decade counter or the mod 10 counter. Each square wave signals from the square wave oscillator is counted using the decade counter. Here CD4017 IC is used as a decade counter. The resistors connected at the output of the decade counter are of varying values and thereby giving a varying output at the decade counter. The diodes used here act as reverse protection diodes. They are fast switching diodes. 

            This varying output of the decade counter will of very small amplitude and thus this output has to be amplified. And hence the next stage is the amplifier stage. Here a 555 IC is used. It is an astable multivibrator. And hence the signal is amplified.

            The amplified output is given to the D flip flop. IC used is CD4013. It has 2 output states. Q and Q̅ . During the first clock pulse Q is in logic 1 state and  Q̅ will be in logic 0 state. When Q is in logic 1 state transistor T1 and T4 will be in ON condition and transistor T2 and T3 will be OFF. Then current will be flowing through the piezotweeter and it will make sound. During this next clock pulse the Q will be in logic 0 state and Q  will be in logic 1 state and during this time the transistor T1 and T4 will be in OFF condition and transistor T3 and T2 will be in ON condition. And thus current flow will be through the piezotweeter and it will make sound. Here we are using bridge amplifier instead of single ended amplifier to get high gain. It is also known as push pull amplifier.

6. COMPONENT LIST

COMPONENTS		SPECIFICATION		QUANTITY
IC		TIMER		1
		CD4017		1
		CD4013		1
		CA3130		1
TRANSISTOR		BD140		2
		BD139		2
DIODE		1N4148		6
CAPACITOR		1µF		1
		0.01µF		1
		330Pf		1
RESISTOR		1K		2
		100K		4
		82K		1
		68K		1
		47K		1
		22K		1
		4.7K		1
		18K		1
	PIEZOTWEETER				1

7. COMPONENTS DESCRIPTION

7.1 555 TIMER IC

            The 555 Timer IC is an integrated circuit used in variety of timer, pulse generation and oscillator applications. The IC design was proposed in 1970 by Hans R. Camenzied and Jim Ball. The 555 has three operating modes:

·         Monostable mode: in this mode the 555 functions as a “one-shot” pulse generator.

·         Astable mode- free running mode: the 555 can operate as an oscillator

·         Bistable mod or Schmitt trigger: the 555 can operate as a flip-flop, if the DIS pin is not connected and no capacitor is used.

Fig 1. Functional diagram of 555 timer

Fig 2. Pin out of IC 555

FEATURES

·         Direct replacement for SE555/NE555.

·         Timing from microseconds through hours.

·         Operates in both astable and monostable modes.

·         Adjustable duty cycle.

·         Output can source or sink 200 mA.

·         Output and supply TTL compatible.

·         Temperature stability better than 0.005% per ºC.

·         Normally on and normally off.

·         Available in 8-pin MSOP package.

APPLICATIONS

·         Precision timing.

·         Pulse generation.

·         Sequential timing.

·         Time delay generation.

·         Pulse width modulation.

·         Pulse position modulation.

·         Linear ramp generator

DESCRIPTION

            The LM555 is a highly stable device for generating accurate time delays or oscillations. Additional terminals are provided for triggering or resetting if desired. In the time delay mode of operation, the time is precisely controlled by one external resistor and capacitor. For astable operation as an oscillator, the free running frequency and duty cycle are accurately controlled with two external resistor and one capacitor.

7.2 CD4013

            The CD4013B dual flip flop is a monolithic complementary MOS (CMOS) intergrated circuit constructed with N channel and P channel enhancement mode transistors. Each flip flop has independant data, set, reset, and clock inputs and “Q” and “ Q̅” outputs. These devices can be used for shift register applications, and by connecting Q bar output to the data input, for counter and toggle applications. The logic level present at the “D” input is transferred to the Q output during the positive going pulse of the clock pulse. Setting or resetting is independent of the clock and is accomplished by the high level on the set or reset line respectively.

Fig 3. Pin out of CD4013

FEATURES

·         Wide supply voltage range.

·         High noise immunity

·         Low power TTL compatibility

APPLICATIONS

·         Automotive.

·         Alarm system.

·         Data terminals.

·         Industrial electronics.

·         Instrumentation.

·         Remote metering.

·         Medical electronics.

7.3 CD4017

            The CD4017BM/cdd4017BC is a 5 stage divide by 10 Johnson counter with 10 decoded outputs and a carry out bit. The CD4022BM/CD4022BC is a 4 stage divide by 8 Johnson counter with 8 decoded output and a carry-out bit. This counter is cleared to their zero count by a logical “1” on their reset line. These counters are advanced on the positive edge of the clock signal when the clock enable signal is in the logic “0” state.

            The configuration of the CD4017BM/VD4013BC and CD4022BM/CD4022BC permits medium speed operation and assures hard free counting sequences. The 10/8 decode outputs are normally in logical “0” state and go to logical “1” state only at their respective time slot. Each decoded output remains high for 1 full clock cycle. The carry-out signal completes a full cycle for every 10/8 clock input cycles and is used as a ripple carry signal to any succeeding stages.

Fig 4. Pinout of CD4017

FEATURES

·         Wide supply voltage range.

·         High noise immunity

·         Low power TTL compatibility

·         Medium speed operation

·         Low power.

·         Fully static operation.

APPLICATIONS

·         Automotives.

·         Instrumentation.

·         Medical electronics.

·         Alarm systems

·         Industrial electronics.

·         Remote metering.

7.4 IN4148

·         IN4148-1 available in JAN, JANTX, and JANTXV

·         Switching diode.

·         Hermetically sealed.

·         Metallurgically bonded.

·         Double plug construction.

·         High switching speed maximum of 4ns.

·         Continuous reverse voltage.

Fig 5. IN4148

FEATURES

·         Glass package.

·         Axial leaded diode.

·         Lead temperature.- 260ºC

·         Maximum trr ≤ 4.0 ns

·         Minimum Bv ≥ 100V

7.5 BD 139

FEATURES

·         NPN silicon transistor.

·         Low supply- voltage range 1.8V to 3.6V.

·         Ultralow – power consumption.

·         Five power- saving modes.

·         Wake-up from stand by mode in less than 6µs.

APPLICATION

·         Audio amplifier.

·         Switching applications.

Fig 6. BD139

7.7 BD140

            These epitaxial planar transistor are mounted in the SOT-32 plastic package. They are designed for audio amplifiers and drivers utilizing complementary or quasi-complementary circuits. The NPN type are the BD 135 and BD 139, and the complementary PNP types are the BD 136 and BD 140.

FEATURES

·         Products are pre-selected in dc current gain.

·         High current (max. 1.5 A)

·         Low voltage (max. 80V)

APPLICATION

·         General purpose power applications

·         Eg. Audio amplifier and switching circuits.

Fig 7. BD 140 transistor

7.8 PIEZO TWEETER

            A piezo(or piezo-electric) tweeter contains a piezoelectric crystal coupled to a mechanical diaphragm. An audio signal is applied to the crystal, which responds by flexing in proportion to the voltage applied across the crystal’s surfaces, thus converting electrical energy into mechanical. The conversion of electric pulses to mechanical vibration and the conversion of returned mechanical vibration back to electrical energy is the basis for ultrasonic testing. The active element is the heart of the transducer as it converts the electric energy to acoustic energy, and vice versa. The active element is basically a piece of polarized material (i.e some parts of the molecule are positively charged, while other parts of the molecule are negatively charged) with electrodes attached to two of its opposite faces. When an electric field is applied across the material, the polarized molecules will align themselves with the electric field, resulting in induced dipoles with in the molecular or crystal structure of the material. This alignment of molecules will cause the material to change dimensions. This phenomenon is known as electrostriction. In addition, a permanently-polarized material such as quartz or barium titanate will produce an electric field when the material changes dimensions as a result of an imposed mechanical force. This phenomenon is known as piezoelectric effect.

Fig 8. Piezo tweeter

7.9 CA 3130

            CA3130 and CA 3130A are op amps that combine the advantage of both bipolar transistors.

            Gate-protected P-channel MOSFET (PMOS) transistor are used in the input circuit to provide very-high-input impedence, very low input current, and exceptional speed performance. The use of PMOS transistor in the input stage results in common mode input voltage capability down to 0.5 V below the negative supply terminal, an important attribute in single supply applications.the CA3130 series circuits operate at supply voltages ranging from 5V to 16 V. They can be phase compensated with a single external capacitor, and have terminals for adjustments of offset voltage for applications requiring offset-null capability. Terminal provisions are also made to permit strobing of the output stage.

APPLICATIONS

·         Ground-referenced single supply amplifiers.

·         Fast sample –hold amplifiers.

·         High input impedence comparators.

·         High input impedence wideband amplifiers.

·         Long-duration timers/ monostable.

·         Voltage follower.

·         Photo- diode sensor amplifiers.

FEATURES

·         Ideal for single supply applications.

·         Pb- free plus anneal available.

·         Common mode input voltage range include negative supply rail; input terminals can be swung 0.5V below negative supply rail.

Fig 9. CA3130

           

8. PCB DESIGN

8.1 PCB DESIGN PR

OCEDURE

8.1.1 Drawing the circuit schematic:

Drawing of the circuit is done through EAGLE (Easily Applicable Graphics Layout Editor) schematic capture software. It includes many libraries with thousands of component symbol. We can select the required symbol from the library and place if in the schematic. After placing the component symbols, we can complete the interconnection using wire os bus control

The next step is to assign to part reference. Each component has to be assigned foot print or PCB art work. The component symbol and foot symbol should correspond in all respects.

8.1.2 Design rule check and net list creation

After the circuit is schematic is completed with all required information such as part reference and foot prints. The design rule check can be used for checking errors, in the design it will check for duplicate symbol, overlapped lines and dangling lines.

After the schematic design and files passes the DRC, check, it is processed by a program called an electric  rule checker thet checks for writing errors. The final operation to be done before starting PCB art work is the net list creation.

A net list creation of components and interconnection along with other information such as foot print, track width etc. This list can be used as an information source for remaining stages.

8.1.3 Creating the PCB art work

In automatic design, the net list obtained from the previous stages is for getting the required foot prints and interconnections. The software used for the PCB network design is the orcad layout.

8.2 PCB FABRICATION PROCESS

The various steps involved in PCB fabrication process are listed below

·         Prepare the component layout.

·         Convert the component layout into PCB layout.

·         Cut the copper clad sheet into desired size

·         Clean the copper-clad sheet.

·         Trace the PCB layout on the copper side.

·         Prepare etching solution by mixing ferric chloride with water.

·         Etch the PCB for the desired time

·         Clean the PCB and drill the pads.

·         Solder the components according to the circuit diagram.

9. SOLDERING

            Soldering is the process of joining two or more similar or dissimilar metals by melting another metal having lower melting point.

9.1 SOLDERING FLUXES

            In order to make the surface accept the solder readily, the component terminal should be free from oxides and other obstructing films. Soldering flux cleans the oxide from the surface of the metal zinc chloride. Ammonium chloride and rosin are the commonly used fluxes. It is used to melt the solder and apply at the joints in the circuits.

9.2 SOLDER

            It is used for joining two or more metal at temperature below their melting point. The popularly used solder are alloys of tin(60%), that melts at 375 F and solidifies when it cools.

9.3 SOLDERING IRON

            It is used to melt the solder and apply at the joints in the circuits.

10. PCB MODULE FORM

11. MERITS AND DEMERITS

          11.1 MERITS:

·         It is a simple circuit.

·         Low cost components are used and hence the circuit is cheaper.

·         It is a portable device.

·         Operation of the device is simple.

·         Easly install

·         Low level input.

11.2 DEMERITS:

·        It is difficult to find out the frequencies that are harmful to different pests.

·        It is not applicable in houses, if there is pets.

12. APPLICATIONS

·       The device can be used in home, Indoor and semi indoor areas, warehouse, food processing units etc and can be used almost everywhere.

·       Here we are not killing the pests just repel them.

13. CONCLUSION

            An ultrasonic pest repellent was designed and constructed. The output has been verified to be of standard quality and it successfully operates even in low voltage. This can modified for wide frequency ranges. This device helps to repel pests but does not kill.

14. FUTURE SCOPE

·         This circuit can be implemented to advanced version using microcontroller.

·         If automatic frequency controller is implemented in this circuit, we can repel different types of pests which is repelled at different frequency.