Hello From EGYPT ,
Today i finished a new project its handheld ultrasonic repeller . We could start with some Acoustical facts i had learned from acoustics course in my university i will sum the in a points :
1- Human could here acoustic wave form 20 HZ to 20,000 HZ (20K)* .
2- Dolphin communicate using 200,000HZ(200K) acoustic wave while elephants use 10 HZ .
3- Acoustic wave is a longitudinal wave produced due to mechanical disturbance so the 2 main contributors are pressure and velocity producing energy and wave could travel .
4- Waves with frequency more than 20 KHZ is called ultrasonic wave and used in many applications such Sonography, NDT (non destructive test ) , under water communication ,.... etc . While waves with frequency below 20 HZ is called infrasound and used in seismology ,Mining ,...etc.
* Upper limit could vary according to age and sensitivity (children could hear more than 20 KHZ ).
Important Note :
If you need Schematic file or ask about any component you have to contact me and with a pleasure i will send them to you .
Device specification :
- Handheld size
- Friendly on environment and health and no effect on birds
- Rechargeable with high battery capacity
- Frequency calibration adaptive with no experts
- High power for long effective range
- Protection key for power saving
- Audible testing included
- Not to put your life in dangerous to test the device .
- Use the charger (10v,200mA) only .
- Not preferable to use close to children's there ears may b sensitive to device frequencies .
- Don't point the device close to eyes , ears or skin .
- Battery included so don't put in fire .
- The device not work with all types of animals.
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Step 1: Design the Circuit and Simulation Using Proteus
Dog Repeller mainly based on producing an ultrasonic waves with frequency annoying dogs and be strange for them so they scare from this sound and ran away .
basic thinking we need a source to generate that acoustic wave with desirable frequency and a speaker for emitting that wave out also we need this device to have a much power to be affected for a wide area also it must be rechargeable to be easy and economic use .
Sound source : We need a sound with about 22-23 KHZ which considered as annoying sound for dogs and never heard before so there are may ways that we could generate that sound as following :
1) IC NE555N > Its a common ic with used in a lot of application and its connection is very simple depending on values for resistors and capacitors connected to it to control the oscillation frequency by charging and discharging the capacitor as an input to the ic and in doesn't need external input ,also you could control the duty cycle with any value you want . the output is a square wave with a very small distortion . you could use many NE555 calculators to do the calculation of resistors and capacitors much easier .
calculator link : http://www.daycounter.com/Calculators/NE555-Calcul...
2) Ring oscillator > Its a good way that depending on the delay of ic's between input and output such Not gate 4069 and the frequency depends on the delay which could be controlled with resistors values connected to it .
3) Analogue oscillator > Its an analogue circuit with transistors biased with dc voltage and also contains capacitors and inductors and have calculations to control the output frequency this method could produce a wave nearly to sin wave but it oscillate bounded .
4) Others IC> could be used under the name clock , oscillator or timer according to their data sheets .
Audio Amplifier : This point will be different according to your country as there are many types of audio amplifier and if i state a definite IC you may not found it . but as a common specification we need audio amplifier support up to 25 KHZ frequency with power > 1.5 watt single or double channel . so you must visit the electronics component shop first and know the available types (Contact me if you want check certain type specification ) .
Check this types : http://www.ti.com/lsds/ti/analog/audio/overview.pa...
Piezoelectric Speaker >This maybe the great challenge (Engineers never says problem) to find a suitable speaker which could operate to 22KHZ or more this depending on voice coil , diaphragm and suspension materials in which all speakers have only 2 parameters on back impedance 4 OHM , 8 OHM or more and power 5 watt ,3 watt,... .
so in order to use the right speaker you should be sure it support such frequency .
Simulation and Analysis
After determining the design and components numbers and parameters you should simulate the circuit before you pay any of these component to be sure that your design is perfect . the values of resistors or capacitor may need to be changes according to the standard values so you should go and repeat frequency calculation again . also you should calculate battery life time you will find it very small due to the high power of amplifier but not to be scared the device is used for only shocking the dog not for long last operation .
For this simulation you could use any circuit simulation program but i prefer proteus you will find all parts and IC embedded in it .
demo version : http://www.labcenter.com/index.cfm
Step 2: TOOLS and COMPONENTS
1) Proteus : Used in design stage for simulation and analysis of circuit .
2) Eagle : Used in fabrication of PCB printed circuit board .
3) Autocad : used in packaging to design the enclosure .
Laboratory devices :
1) DC source
Tools and Equipments :
1) AVO meter
2) Wire Clipper , pliers and Screw
3) Connecting wires different colors
4) Glue for plastics
6) Soldering Iron ,soldering flux and soldering wire.
7) Laser cutting machine
8) clothes iron
9) Laser printer
10) Acrylic sheet (400*300*3 mm)
Electronic Components :
1) NE555N *1
2) Audio Amplifier (>1Watt preferred) *1
3) 9V rechargeable battery and battery caps *1
4) ON / OFF tiny switch *2
5) Push button (Normally opened ) *1
6) LED (Yellow , Red , Green ) *3
7) N4004 Diode
8) Piezoelectric speaker (frequency up to 50 KHZ)*1
9) Charger (9-10V) and Charger socket
10) 1/4 watt Resistors *5
11) Capacitors *3
12) PCB board (90 * 50 mm)*1
13) Glossy paper A4*1
14) Ferric chloride acid small bottle
Step 3: Testing Components and Connecting Circuit on Breadboard
From most important steps is to test the component you will use because simply is an ic is down so you will think that your design have some thing wrong but it doesn't .
First : Test the NE555 to be sure that its working and output is precise square wave this done using the oscilloscope with suitable time per division according to your output frequency . Then test the Amplifier output comparing input and output in different channels of oscilloscope .
Second : Connect the circuit as shown in schematic on breadboard and display the output from oscillator first then input and output of Amplifier . Check the frequency output form amplifier it should be 22,000 KHZ less than that will not be acceptable also you will notice that the square wave not precised clear and this is a disadvantage in this way due to the loading effect . using large speaker cause highly loading effect so larger distortion than the speaker i used .
Third : Acoustic power calculations (this part is really hard to discussed there you could contact me it it is needed) but as a summery from the Amplifier data sheet you will find efficiency curve VS frequency and temp , we assume constant temp 27c so we now had the efficiency at 22KHZ after that , efficiency is the Output Acoustic power over input Electrical signal (it need an equivalent circuit for speaker you will find it in datasheet) the whole equation will be in terms of resistors values so you could control Acoustic power .
Third : if the output as you watched in video so you are ready to test the device with a dog (as an advice do this with small dog or your dog don't disturb a wild dog) :D .
Step 4: PCB Design and Fabrication Using Eagle
In order to finish up your project you have to convert the circuit from breadboard to printed circuit board . Its a lot easy steps that are followed to produce a well fabricated PCB .
there are a lot of techniques to fabricate pcb such as :
1) Ink heat transfer method :
step 1 : the fabrication starts from routing software which is eagle (also you could do this by proteus but i prefer eagle so simple and routing algorithm is better) , eagle used to draw a schematic of your design then to convert it to a board design which have the routing buses . It's so easy and you could learn it in hours , so after you route the design with suitable pcb size and suitable wiring (you should leave distance between buses or wires to avoid electromagnetic coupling between then due to high frequency).
step 2 : Print this design on glossy paper mirrored (most important point) using laser printer (second most important point)
step 3: Clean the piece of pcb board very well using smooth sandpaper in order to remove oxidized layer and fingerprints ( so don't touch it again ) . Cut the glossy paper around the design and leave about 0.5 cm margin from all sides and put the printed design face in face with the copper layer
step 4 : Use clothes iron making circles for silk mode temperature until you find the printed design starts to appear leaving the paper down to the copper layer . leave it to cool the wash it by water to remove the papers from it .
step 5 : Put the board in etching acid ferric chloride until it etch all uncovered copper and leave the ink covered copper this took about 20 minutes according to concentration of your acid .
step 6 : Use the electric drill to open holes for through holes component .
step 7 : Mount your components according to the schematic and solder them using the iron solder and soldering wire .
step 8 : Check the circuit and connect power to it .
2) CNC routing machine :
This it the best method to fabricate the PCB if you had a CNC machine . after design the routing and buses by eagle the output file is used by the software of the CNC after determining layers of removing copper and layers of drilling so you don't have to drill or acidic etching.
3)UV exposure :
It is similar to first method but instead of using acid we use ultraviolet light to act with ink and do ink transfer to copper .
and there are of course many of other methods to do this
Step 5: Enclosure Design and Mounting Components
The last touch for the project is to make an enclosure to looks like real device so i made the enclosure from acrylic material because i already learned to cut the acrylic by laser cutting machine so i designed it by autocad 2D and determined places of LEDs , Switches and charger socket then export the file to be cutted and i collected it back using either glue , epoxy or chloroform .
Connect the switched , LEDs and socket and solder them to their places in the circuit using the connecting wires according to the design schematic .
Step 6: Contact Me for Any Information
Mohamed Ibrahim Hanfy
Communication and Electronics department
Faculty of Engineering - Alexandria University - Egypt
Email : Mohamed.firstname.lastname@example.org | email@example.com
Phone : +201278686775