This paper reports the design and construction of a security system. The system will produce sound of a barking

dog at audible frequency of 9 KHz. The design procedure and principle of operation of the various modules as

presented in this work are based on the locally available electronic component

Adedayo, K.D

Adekola, A.S

Arogunjo, A.M

Usikalu, M.R.

English

Covenant University Repository

 Journal of Emerging Trends in Engineering and Applied Sciences (JETEAS) 2 (2): 235-238  (ISSN: 2141-7016)  235   The Design and Construction of an Infrared Activated Security System at 9 Khz Frequency  1M. R. Usikalu, 2K. D. Adedayo, 2A. S. Adekola and 2A. M. Arogunjo  1Department of Physics, Covenant University, Ota, Ogun State 2Department of Physics, Federal University of Technology, Akure, Ondo State, Nigeria Corresponding Author: M. R. Usikalu __________________________________________________________________________________________ Abstract This paper reports the design and construction of a security system. The system will produce sound of a barking dog at audible frequency of 9 KHz. The design procedure and principle of operation of the various modules as presented in this work are based on the locally available electronic components __________________________________________________________________________________________ Keywords: infrared, transmitter, receiver, frequency, multivibrator, stable, monostable, voltage __________________________________________________________________________________________ I%TRODUCTIO% The opto-electronically controlled security system is to automatically detect the presence of unauthorized person(s) entering or leaving a given area and to notify the security personnel accordingly. In notifying the security personnel, a sound of a barking dog is produced by the system since it has been designed to operate at audible frequency of a barking dog. The system is therefore a dog in disguise.  The system has many advantages over other security systems where the presence of intruders is detected by photocells. The cell has inherent inefficiency in that it is either shadow or light operated which the intruder can bypass. Opto-electronically controlled security system incorporates infrared emitting diode at the transmitter end and phototransistor at the receiver end. The design, construction and testing of this work was done in the Department of Physics, Federal University of Technology, Akure. The design of the work as presented in this report has been based on the locally available electronic components in Nigeria such as infrared transmitter and receiver, transistors, resistors, capacitors, 555 timer etc.  Technical Design and Operation of Various Modules The block diagram of the work is presented in Fig 1. It consists of infrared transmitter, infrared receiver and other circuitry. The design procedure and selection of the components for the various units are hereby presented.      The Infrared Transmitter is the unit that generates the infrared light via infrared emitting diode (IR emitter). The transmitter uses the 555 timer configured in the astable mode as shown in Fig 2. The astable multivibrator is also called free running multivibrator and generates a continuous digital signal or train of pulses whose period is given as [Anyanwu et al., 1987] T = C1 (R1 + 2R2) ln2   (1) The frequency F of the output pulses is also given by F = T1      (2) In this work, the frequency of operation has been taken as 9.0 KHz, which is within the range of audible frequency of a barking dog. The pulse therefore has a period of 0.11 mS. C1 is a capacitor and must have a low valued capacitance as to avoid unnecessary charging and discharging [Horowit and Winfield, 1997; Lehman, 1997]. The value chosen is 1.0 nF. According to the design, R2 is to be approximately twice that of R1 [Horowit and Winfield, 1997]. Using Eq. (1), their calculated values are R1 = 82 KΩ and R2 = 39 KΩ   The output of the astable multivibrator at pin 3 is connected to a constant-current source transistor, TR1. This then provides the infrared transmitting diode, D3 with a current, which pulsates in rhythm with the output signal of the astable multivibrator. The circuit diagram of the infrared receiver in this work is presented in Fig 3.  The transistor, TR2 is the phototransistor and it senses the infrared signal emitted by the transmitter. The transistors TR2 and TR3 formed a cascaded amplifier, which then amplified the detected signal and ensures that the output signal from the unit is in phase with the incoming pulsating infrared light. The output voltage from TR3 can be measured using [Maddock and Ca cut, 1988] +=4231980 1RRRRRRV                       (3) Equation (2) gives V0 = 1.33 V, which is reasonably comparable to the measured value of 1.46(5) V with 9.77 % difference. This difference may be due to the components tolerance. This output goes to the input of a non-inverting amplifier, A1. This is to achieve more amplification of the signal. The output signal of Journal of Emerging Trends in Engineering and Applied Sciences (JETEAS) 2 (2): 235-238 © Scholarlink Research Institute Journals, 2011 (ISSN: 2141-7016) jeteas.scholarlinkresearch.org  Journal of Emerging Trends in Engineering and Applied Sciences (JETEAS) 2 (2): 235-238  (ISSN: 2141-7016)  236  A1 is an alternating signal with high frequency. This then passes through half-wave voltage doublers to rectifier it and double the voltage of the signal.  The comparator A2 is meant to generate the triggering pulse for the time delay. When the non-inverting voltage is larger than the inverting voltage, the comparator produces a high output voltage equal to the supply voltage. When the non-inverting input is less than the inverting input, the comparator produces a low output voltage. As long as the receiver receives the pulsating infrared, the output of the comparator remains high. When a person breaks the pulse stream by passing between the transmitter and the receiver, the output from the receiver goes low and hence triggers the time delay using a negative edge trigger. The time delay and clock pulse circuits used in this work are shown in Fig 4. This determines the time delay operation of the system. A 555 IC has been configured as a one shot multivibrator or in a monostable mode. This produces a single pulse by using the external components C7 and R15. The circuit triggers when a negative going pulse (this is obtained when an intruder breaks the transmission of infrared light) is sensed through pin 2. The pulse duration time T is given by [Maddock and Ca cut, 1988; Day et al., 1976] T = 1.1 R1C1        (4) The values of external components are C7 = 1.0 µF and R15 = 100Ω. These have been chosen to ensure that the frequency of 9.0 KHz is maintained.   The clock pulse circuit also uses 555 IC in an astable mode. This has been design to generate continuous pulses. The output of the clock pulse is determined by the input signal at pin 4, which comes from the time delay circuit. As long as the signal at pin 4 is high, train of pulses is generated at the pin 3 of the clock pulse circuit, the period of which is determined by R16, R17, C9 and C10.   The pulses generated by the pulse generator are meant to drive the monostable relaxation oscillator for the time delay of 60 seconds. This triggers the oscillator to start barking at the audible frequency of a dog. To maintain this time delay, the values of components that made the clock pulse generator are R16 = 22KΩ, R17 = 122KΩ, C9 = C10 = 10 µF. The circuit adopted to oscillate at this time delay is presented in Fig 5. This generates the output signal whose frequency depends on the charging of capacitors C11 and C12. The pulse frequency from the oscillator that controls the output frequency of the voltage-controlled oscillator (VCO) is given by              )(71121118 CCRF+=      (5) The Voltage Control Oscillator (VCO) circuit provides varying output signal typically of square waveform whose frequency can be adjusted by a dc voltage [Lehman, 1999; Jones and Scott, 1993]. The Voltage Control Amplifier (VCA) ensures that the single pulse generated by the VCO can only get to the band pass circuit when the switch S1 is closed. The circuit diagram of Fig 6 presents the VCO and VCA that have been used in this work. Potentiometer, P1 determines the highest frequency that can be generated at the final output while P2 is to set how we want the audible tone to decay. Their values are 1MΩ and 50KΩ respectively. It should be noted that comparators A1 to A4 are TL084 IC.  This circuit of band pass filter used in this work (Fig 7) permits the signal of desired frequencies to pass. The bandwidth of this type is the difference between the upper and lower frequencies. In this case the lower frequency FL is 20 Hz while the upper frequency FH is 200 KHz since the audio frequencies of a barking dog is between this range. The bandwidth of the filter and the center frequency F0 are related by the Q factor, which is defined by [Maddock and Ca cut, 1988; Day et al., 1976]  LH FFFQ−= 0         (6)  For typical audio filters, the values of the capacitors are between 0.01 and 0.1 µF. In this work, C18 = C19 = C = 10 nF. The values of other components that made up the band pass filter have been calculated using Eqs. 7 – 9 with gain, G taken as 0.4 [Maddock and Ca cut, 1988].  GCFQR02722π=                                  (7)  02328 2)2( FGQQPRπ−=+            (8)  CFQR02922π=                        (9) The output signal from the band pass is of low amplitude and must therefore be amplified before getting to the speaker. Two power amplifiers IC LM 386 have been used. They have been cascaded to enhance the efficiency of their operation. The arrangement of the components is presented in Fig 8. The unit that supplies necessary dc voltage to various units of the project is presented in Fig 9. C25 – C28 are smoothing capacitors to filter the ripples from the rectified voltage and to give a better approximation to the dc voltage. The voltage regulators that have been used in this unit are 7809 and 7909 to supply +Vcc and –Vcc respectively, to the appropriate unit of the project as required. The diodes D9 and D10 are protecting diodes, which are meant to protect the power supply against short circuit.  CO%STRUCTIO% A%D TESTI%G  It should be noted that in drawing the circuit diagrams, an electronic workbench, which is a computer-drawing package has been employed. For effective and reliable operation the transmitter and the receiver are not to be more than 2 m apart.    Journal of Emerging Trends in Engineering and Applied Sciences (JETEAS) 2 (2): 235-238  (ISSN: 2141-7016)  237  SUMMARY A%D CO%CLUSIO% This paper has reported the design procedure and construction of a security system. This has been designed to operate at an audible frequency of 9 KHz. This work would offer assistance to our security personnel on guard to have a thorough monitoring and control over the area of their operation.  REFERE%CES Anyanwu I. J, Bishop O. N. and Olapade O. L. 1987 Basic Electronics. Macmillan Publishers Nigeria.  pp 51 –127.   Horowit P., Winfield Hill 1997. The Art of Electronics, University Press, Cambridge, New York. pp 348 – 354   Maddock R. J. l, Ca cutt D. M. 1988 Electronic a course for Engineers, Longman House, Burnt Mill, Harlow, England. pp 99-286  Day G.W., Hamilton C.A. and Pyatt K.W.  1976. Spectral reference detector of the visible to 12 micrometer region: convenient, spectrally flat, Appl. Opt. 14, 1865-1868   Lehman J. 1997. Pyroelectric trap detector for spectral responsibity measurements, Opt. Photon. News 8, 35-36 (1997) also published as Appl. Opt., 36, 97   Lehman J. 1999. Calibration service for spectral responsivity of laser and optical-fiber power meters at wavelengths between 0.4 µm and 1.8 µm, NIST Special Publication 250-53   Jones R.D. and Scott T.R. 1993. Laser-beam analysis pinpoints critical parameters, Laser Focus World 29, 123-130   APPE%DIX                  Fig 1: Block diagram of opto-electronically controlled security system   Fig 2: Circuit diagram of the infrared transmitter   Fig 3: Circuit diagram of the infrared receiver   Fig 4: The time delay and Clock pulse generator circuits used in this work  Infrared transmitter Power supply  Infrared receiver Time delay and clock pulse Monostable Relaxation Oscillator Voltage control Oscillator & Voltage control Amplifier Band Pass Filter Output Amplifier unit Speaker signal  Journal of Emerging Trends in Engineering and Applied Sciences (JETEAS) 2 (2): 235-238  (ISSN: 2141-7016)  238   Fig 5: The circuit of Monostable Relaxation Oscillator   Fig 6: Circuit diagram consisting the VCO and VCA     Fig 7: Circuit diagram of the band pass filter    Fig 8: The output power amplifier circuitry    Fig 9: The circuit diagram of the power supply   

The Design and Construction of an Infrared Activated

Security System at 9 KHz Frequency

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The Design and Construction of an Infrared Activated Security System at 9 KHz Frequency

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