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    The electronic dog repellent circuit diagram below is a high output ultrasonic transmitter which is primarily intended to act as a dog and cat repeller, which can be used individuals to act as a deterrent against some animals. It should NOT be relied upon as a defence against aggressive dogs but it may help distract them or encourage them to go away and do not consider this as an electronic pest repeller.

    The ultrasonic dog repellant uses a standard 555 timer IC1 set up as an oscillator using a single RC network to give a 40 kHz square wave with equal mark/space ratio. This frequency is above the hearing threshold for humans but is known to be irritating frequency for dog and cats.

    Since the maximum current that a 555 timer can supply is 200mA an amplifier stage was required so a high-power H-bridge network was devised, formed by 4 transistors TR1 to TR4. A second timer IC2 forms a buffer amplifier that feeds one input of the H-bridge driver, with an inverted waveform to that of IC1 output being fed to the opposite input of the H-bridge.
    For more electronic dog repeller circuits check the related links bellow.

    Cat and dog repellent circuit diagram

    dog repellent circuit schematic

    This means that conduction occurs through the complementary pairs of TR1/TR4 and TR2/TR3 on alternate marks and spaces, effectively doubling the voltage across the ultrasonic transducer, LS1. This is optimised to generate a high output at ultrasonic frequencies.

    This configuration was tested by decreasing the frequency of the oscillator to an audible level and replacing the ultrasonic transducer with a loudspeaker; the results were astounding. If the dog repellent circuit was fed by a bench power supply rather than a battery that restrict the available current, the output reached 110dB with 4A running through the speaker which is plenty loud enough!

    The Dog and Cat repellant was activated using a normal open switch S1 to control the current consumption, but many forms of automatic switching could be used such as pressure sensitive mats, light beams or PIR sensors. Thus it could be utilise as part of a dog or cat deterrent system to help prevent unwanted damage to gardens or flowerbeds, or a battery powered version can be carried for portable use. Consider also using a lead-acid battery if desired, and a single chip version could be built using the 556 dual timer IC to save space and improve battery life.

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    59 Responses to "Dog Repellent Project Circuit"

    1. Steev Gray says: on February 8, 2009 at 4:58 pm

      I want to build a dog repeller circuit like this.. can you give me a part number/supplier for the ultrasonic tranducer. I can’t find anything small (1 inch diameter) that goes into the 40KHz range.

    2. ronstuff says: on April 25, 2009 at 12:12 am

      Hi dude, nice schematic. Forgive me if I’m mistaken, but isn’t pin 2 of the 555 timer usually the input and pin 3 the output?

      IC2 has pin 2 connected to the bases of TR2 and TR4 and it might turn on TR4 but I don’t see it being able to turn on TR2 unless pin 2 can also become an output.

      Same thing with pin 3. I don’t know how IC2 can be triggered if the input is connected to the output.

      What do you reckon?

      • I built it & it didn’t work. then I noticed the same thing; output of IC2 is no.3 should go to base of TR2 & TR4 so I switched # 3 & #2 on IC2. I tested with 5, 12 & 17 voltDC power supplies. TR2 overheats with 12 volts, TR 1, 3 7 4 remain cool. AC output voltage of IC1 was 7.7 volts. AC output of IC2 was 9.7VAC
        Meanwhile squirrels came & ate most of my red currents. I was going to use it to repel them


    3. Hello again,
      Made a mistake on the first message.
      It should have read 100 watt nor 10,

    4. Does anyone has a sample of the circuit board for this? Or ya all used wires

    5. The Circuit can be built on stripboard quite easily as layout of components is not that critical, but attention must be paid to polarization ie make sure the 556 dual chip or 555 chips are placed in polarised sockets, so you dont have to remember where pin 1 is etc, and mount them last to save heat from the iron reaching them. The Transistors can also be substituted for other similar types. I mounted them on a 6 x 4 extruded heatsink, all insulated of course, which made the housing space a little larger, but I disguised it as a bird nest box so that the neighbours wont know what I am up to, as the unit faces their garden toward the place where their dog continually barks. The dog hasn’t barked for about two weeks so now so I will try turning it off. Its a good idea to incorporate the switch so that the unit can be switched on/off [especially if a dog only barks at night], it can be turned off to save power during the day if batteries are to be used, but mine was on continuously, run from the shed supply with a stabilizrd supply. If you have a scope set the frequency to just below 25Kz. This works for me but you may have to fiddle with the frquency a little for smaller dogs as their hearing range is a touch higher. Hope this helps. HL.

      • Hi HL,

        Did you build this circuit and did it work?.

        In order to make it work, can you tell me what is the modification/alteration has been done to the original circuit? Do you change the IC2, pin #3 and pin2 to make it work?

        Best Regards


      • Hi HL,

        It is possible for you to send photo of your project to me?….Do you have PCB layout of the circuit?




      • me too… i want the PCB layout/Rimu for this circuit… or you can also give me the simulation(OrCAD, pSpice, matlab or Tina) for this circuit….

      • Can you please tell me if I can add a variable resistor to change the frequency.
        T’m trying to get a range of 25KHz to 40KHz. If so, what size and where is it placed.
        Thank you for your time

      • Hi Guys,

        This project might be able to solve my dog pooping problem. I have two questions;

        1/ What amount of power output would I need
        to cover about 40 feet? and

        2/ Where could I find the required

    6. To Kamil. I did not make any mods to the circuit, except that I used TIP2955 & TIP3055 transistors. The pins 2 & 3 on the circuit is probably a misprint and need to be transposed. I cannot send picture as it is fixed in a bird box to disguise it. Just use a piece of strip board with copper strips on one side. All the components except the speaker and transistors were mounted on the board, 24 x 30 holes gives plenty of room. Use sockets for the chips and insert them first [one above the other with about a 6 hole spacing], and build the circuit around them. Flying leads were used to connect the speaker and Transistors and supply. Use coloured leads to save confusion. Layout is not critical. I used the track at one edge for +ve & the oposite track for -ve, placing all other components and wiring somewhere in between. If you are having problems it is a good idea to draw out the circuit as you build it, and compare with the original….in this way you can see if you have missed any connections etc. Hope this is helpful. HL.

    7. To Dave regarding squirrels…..Maplin have an electronic gun for sale [9.99] which you point towards the squirrels and pull the trigger. The squirrels disappear quickly….well they did for me!. The gun has 2 switched tones, one of which is audiable, and it looks a little like a small loudhailer. After using for about 4 days no squirrels returned to ravage the plums on my tree. The other option is to feed them with peanuts, and they will leave your berries alone. but I havent seen a squirrel for about 2 weeks now. Worth a try. HL.

      • Did any one find a local source for the UltraSonic Transducer ?

        I live in Phoenix and was wondering if anyone had any suggestions – or do you know of somewhere online I can get one ?

    8. The schematic is basically the same as this one:
      What I don’t understand though is why C2 capacitor goes to +V rather than ground.
      …Good on you Harry for silencing the damn dog!

    9. Can i mount the transducer in such a way that the sound waves are “directioned”. ie to point to my neigbors yard and not irritate my dog in ny property??

    10. Akshat Gupta says: on April 27, 2010 at 6:05 pm

      Respected sir please send me all the details of this project so that it could of help for me to make it my final year project

    11. chuck says: on May 2, 2010 at 9:14 pm

      Hi everyone,

      I would like to build this circuit, but dont have the means of etching a circuit board. I’m not familiar with strip board, sounds like it is perferated circuit board with copper strips on one end? I couldnt seem to find anything like this at digikey, does it have a different name? Would this involve wire-wrapping all the low current connections?

    12. .Now tell us if there are any changes in the ic pins dude

    13. I would like to builyour cat/dog deterent for my garden hlll tyhts cpt fo the U/S transducer. Can you advise me of the type you used and where I might purchase one/
      Ian Mitaxa

    14. i has to do this cat and dog repellent project for a final test project… i’m so so worry either this project functioning as well… issit the circuit are totally correct…?

    15. Is this the corrected circuit?
      “Cat and dog repellent circuit diagram”
      Please, reply.
      It would not work. The total consume current is 30mA just at DC9V3.
      [P.S: i have use TIP31A, TIP32A , TLC555 timer(2v to 16V) and TR40-14C(brand audiowell ultrasonic transducer transmitter] parts.

    16. can someone help me i want to make the fixed-frequency audio tone generator

    17. This is very useful schematic… i am going to try this circuit.. and if doubt arises means clear my doubt sir….

    18. I purchased a ultrasonic air transducer at:

      I have not yet built this circuit but hope to use 2N3773 & 2N6284 power transistors, you can get from Digikey.

    19. if a person wanted to make this circuit a variable frequency circuit, which components would need to be substituted? thnx!

    20. Hi guys.

      This schematic does not work because someone does not want it to work. Clearly some information has been changed.

      An astable 555 timer with just one R and one C will conform to the equation:

      f=0.72/(R x C) where f is kHz and R is kOhms and C is in micro farads.

      You want to keep R2 (on both IC’s) at 1K Ohms and you want f to be ~20kHz off each to give you ~40kHz.

      The two IC’s together will make up the 40 kHz.

      Doing the math then, you find C2 and C4 need to be 33 nF. Also on pins 5 of IC1 and IC2 make the capacitors both 10 nF.

      Lastly as pointed out by Ronstuff in April 2009. The connections to pin 2 and pin3 on IC2 need to be swapped around. A very basic 555 error. This is what makes me think the circuit was “hacked”

      Nick asked, why does C2 go to Vcc? Nick the reason is you want the wave form off IC1 to be the opposite of that from IC2.(one is inverted to the other) So one IC has has C going to Vcc and the other IC having C going to ground. Yes its surprising, the 555 timer will work happily like this. Its part of the brilliance of this schematic.

      Lastly, BD131 / 132 can be more difficult to source these days. The TIP2955 / TIP3055
      as used by Harry are fine and less prone to overheating.

      Have fun.. David

      • I have a project of this sort I require someone to build but in a pendant size format.
        Can it be done with a(part B)radiant distance trigger?
        (ie. to stop a dog approaching a cat).

        If you are interested, please contact me for more explanation.

    21. Hey Guys

      I am having a similar problem with dogs,not the barking issue but various neighbors using my property as the neighborhood dog toilet. Animal control has fined a few which simply generated vindictive behavior of them bringing their animals intentionally to defecate more so on my property. Unfortunately I live in an area with a partial section 8 populace which are impossible to reasons with.I need something that is covert because anything ground level with motion detection is just going to be smashed or stolen. Ideally I would rather mount something under the eve of the roof with sufficient output to deter dogs from wanting to be there to do their business and I need something that can be active 24 hours a day with perhaps 200 feet coverage. Any suggestions here would be greatly appreciated as I am at my wits end.Anytime animal control fines these numbskulls they then brake something on my property out of spite so the covert method I think here is the only solution. I was thinking of just buying a variable oscillator like the old test bench models and trying to find a speaker that could handle the high frequency range. Thus far I don’t see any manufactures of horn like outside speakers capable of up to like 35K.
      Please any assistance would be very much appreciated. I’m not very savvy with building IC circuits I’m in the vacuum tube age group.


      • Hi Helga, sadly I haven’t found any electronic dop repellent with such a large coverage. On Amazon for example is only one product powerd from the main supply or batteries and has motion detection. They say it picks up motion up to 85 ft away, so I guess it has a minimum range of 85 feet. Maybe if you buy 2 of them and place them is the right configuration then you can cover 200 ft. Check it out – http://amzn.to/Electronic-Yard-Fence

      • With situations like this. Film them brining their animal to your property and also the vandalism. If they think it’s acceptable then they should accept the fine, although, as we all know with people like this they’re often very selfish and arrogant. But you have every right to film them and it sounds like you HAVE exhausted all avenues of reasonable redress. The only thing people like this understand is a fine. Any abuse..ignore it; film it; report it. Don’t let it get to you, that’s what they want, and the more you refuse to take the bait the more angry they will become with themselves. Also, wouldn’t it be horrible if someone picked up THEIR sh*t and dumped it back on their drive..as with the fine, it’s the only thing they understand. Of course, I’m not advocating you do this personally ;) Take care my friend.

    22. The problem with this style unit is that since it’s ground mount the jerks will steal it or smash it. I really need something that is more covert and not motion activated but rather on all the time. I bought a bench test oscillator and am trying to find speakers to use with it. I am wondering if these piezo buzzer things would work with the test bench unit. The test bench oscillator puts out 14 watts according to it’s specs but I have no idea at what impedance etc. If those buzzer things need one watt maybe one could gang 14 in parallel or pad it with a resistor???? If I can get the thing to either look like a home security alarm with some ultrasonic horn or set the test bench oscillator inside and run wire to just those buzzer things I could easily hide the buzzers inside something that draws less attention. Anything I can mount under the roof eve would be best.

      • You may consider installing a Closed Circuit TV (CCTV) surveillance setup that employs motion sensing through the video camera/software, to remotely activate the ultrasonic noise generator.

    23. Pentaconto says: on August 5, 2011 at 7:02 pm

      This circuit is not correct. Looking at the diagram, notice that at first glance:

      The outputs of IC1 and IC2 (pin 3) are connected between its. The output of IC2 should be connected to the bases of transistors TR2 and TR4, and the output of IC1 should be connected to the control input pin 2 of IC2.

      In addition, there is no limitation to the base bias current of the 4 transistors, it would take at least limiting resistors, also this avoid short circuits the outputs of IC1 and IC2 to ground or Vcc through the base-emitter junctions of transistors.

      Is this circuit ******REALLY**** has been checked, or is a project unchecked ? (Or a bad copy of another similar circuit?)

      Please check what publihs on this website.

    24. this circuit really works? any one make it and test it?…

    25. I have the circuit outputting a wave form and I can
      control the frequency with the caps. The frequency does not comply with the formula stated above. The main problem at this point is that there is very little gain achieved in the H bridge and what comes out is not a square wave. What about a couple of base current limiting resistors to prevent possible saturation?

    26. PS
      I did make the changes regarding the ins and outs of the two ICs mentioned above to get it this far. I have made those changes to the schematic but I don’t have a way
      of up loading it in a reply.

    27. Cat and Dog Repellant Circuit

      Dear Sir,

      The transistors BD131-132 are difficult to find and can you help me to find the most suitable equivalent transistors to replace BD131-132.


    28. I used the Tip41NPN and Tip42PNP

      • Dear Jed,

        Thanks for the reply but you have not mentioned the results as I wonder the ft of TIP 41 is 3Mhz whereas the BD 131 is >60Mhz. Please confirm before I buy for those Transistors.

        Appreciate very much once again.



    29. I am not confirming snot, if you want to buy them buy them if not then don’t. Got to help yourself!

    30. Look up H bridge circuits and see if you
      find any with the emitter as the output
      like these. This whole project seems to be
      a bad joke.

    31. For a correct version of this circuit, see:

      Dog Bark Stopper

      Colin Mitchell

    32. Hi everyone..!! I have a doubt..
      In my home 4 -5 street dogs have made their permanent residences at the top floor & they pose a serious menace. They come to bark at and bite the one, who comes to shooo it away.. I want to drive them away from my home. Will this circuit be a suitable solution for it? Pl. reply soon …

    33. ceana reyes says: on January 5, 2012 at 8:08 am

      I want to build a dog repeller circuit like this.. can you give me a part number/supplier for the ultrasonic tranducer.

    34. Dear Sir,
      > Pls I have QT for ‘Auto model’ “Ultrasonic Rat Repellent” .
      > And cover parking area 2000 sq ft.
      > Neeraj
      > Kleenair Systems Pvt.Ltd.
      > Kleenair House- Unit – II,
      > Gat No- 120 to 122, A/p Pirangut,
      > Tal – Mulshi, Dist – Pune – 412411.
      > Phone No – 020 – 66750380/81.
      > Mob- 9766354647.

    35. algorithm says: on January 19, 2012 at 3:40 pm

      maybe You have an idea, what will be algorithm of dog repellent, Which could be write down on Matlab?
      What is sampling rate?
      How to designed generator (maybe filter in right mode? ) with variable frequency ?
      Thank You

    36. Look on eBay for Piezo Tweeter for about $3.00 plus $7.00 postage. The maximum frequency response will be about 30kHz.

      This is the cheapest and best item for the output device.

    37. wat is da exact ic dat i ned 2 use 4 dis circuit???

    38. I built it & it didn’t work. then I noticed the same thing; output of IC2 is no.3 should go to base of TR2 & TR4 so I switched # 3 & #2 on IC2. I tested with 5, 12 & 17 voltDC power supplies. TR2 overheats with 12 volts, TR 1, 3 7 4 remain cool. AC output voltage of IC1 was 7.7 volts. AC output of IC2 was 9.7VAC
      Meanwhile squirrels came & ate most of my red currents. I was going to use it to repel them

    39. This project made me remember when I first bought one of this dog repellent devices. Let me share you some of my experiences.
      I have noticed that puppies a few month old and young dogs can hear the sound and get scared easily, but new borned and old ones cannot hear the ultrasonic frequency. Also, some dogs become more aggressive. Cats can hear it too but most of them are not scared by the sound, probably because it’s not an annoying frequency.

    40. This circuit is incorrect and will not work as drawn. For a start, the output of both 555 timers are connected together, and the transistors on the right side are being ‘driven’ by one of the 555 timer inputs.

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