Emmanuel Galleto

user Test Engineer

city ISI

  • Dog Repellent Ultrasonic Circuit

  • Created: Mar 17, 2014

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When we hear the word “Ultrasonic" we often refer it to bats and dolphins communication. Technically, “Ultrasonic" applies to sound that is anything above the frequencies of audible sound, and includes anything over 20kHz. Frequencies used for medical diagnostic ultrasound scans extend to 10 MHz and beyond. This dog repellent ultrasonic circuit will chase away angry dogs. It comprises of a 555 timer IC, a speaker/piezoelectric and a little ferrite transformer.

The main part of this circuit is a 555 timer IC. A 555 timer IC is an integrated circuit (chip) used in a variety of timer, pulse generation, and oscillator applications. The 555 can be used to provide time delays, as an oscillator, and as a flip-flop element. Derivatives provide up to four timing circuits in one package. You can use the 555 effectively without understanding the function of each pin in detail. Frequently, the 555 is used in astable mode to generate a continuous series of pulses, but you can also use the 555 to make a one-shot or monostable circuit. The 555 can source or sink 200 mA of output current, and is capable of driving wide range of output devices.

To use this circuit adjust R3 at resonance frequency of the piezo transducer for maximum amplitude of the repeller ultrasonic sound. At 30 KHz this can reach a value of 108 Vpp. Without the piezo the output voltage is around 200 Vpp.

Note: Ultrasonic frequency must be set with a dog nearby.


EE15 Ferrite Transformer

555 Timer


Switch NO

10nF Capacitor

1N4004 Diode (3 Units)

2.2kΩ Resistor (2 Units)

4.7kΩ Variable Resistor4.7kΩ


3.3V Capacitor (2 Units)


Check out another Dog Repellent Circuit.



hmmm, signed up for this site only to find it not so helpful when people just post a circuit with no values or explanation. Your are not helping to grow the number of participants on this website by posting a circuit with no values or explanation. I'll look around the site and see if this is typical. If so, I won't return and make sure others know it was a waste of time.

Posted: Apr 03, 2014

Emmanuel Galleto

Hi Larzman., Sorry for the circuit that has not yet finished. I just want to create a circuit i want and its still on the process. im kinda lazy in finishing my circuits. Maybe you could see other peoples project if you want. Thanks by the way for the comment God Bless =)

Posted: Apr 09, 2014

Emmanuel Galleto

Hi Larzman, Had done a little tweak with my project hope it would please you.

Posted: Sep 30, 2014


interesting project emmanuel. I dont know anything about electronics but would like to build such fun stuff with my son. May be there can be videos of the physical components to use and how to go about building this over a weekend. That would be very inetresting. Thanks.

Posted: Oct 11, 2014


Umm, im guessing this supposed to work from 2x 1.5v batteries(judging from the cap rating? Also, u missed pin #2(u have 2 #3 pins). Have u actuAlly built this circuit? It seems flawed

Posted: Feb 03, 2015


Hello Emmanuel! How can you drive the piezo directly from the 555? This won't be a very loud deterrent I'm afraid. Unless it's just meant as a whistle for your own dog?

Posted: Mar 20, 2015


You might want to flip C1 and C2 for the correct polarity. The voltage rating on these caps should be higher. I would do it a bit different to get a 50% duty cycle and have RP3 to vary the frequency only. A bypass cap for the power supply would be nice. And should use use a LMC555...

Posted: Mar 26, 2015


Forgot to mention... Can use much lower values for C1 and C2.

Posted: Mar 26, 2015


I would also increase the R1 value by 10X in order to save power and use an ultra-bright LED. :)

Posted: Mar 26, 2015

Emmanuel Galleto

@cicel thanks for the advise i did some tweaking, i totally forgot about the polarity. I agree with you to increase the value of R1 to save more power.

Posted: Apr 27, 2015

Emmanuel Galleto

@henry you could check this other Dog Repellent Circuit http://schematics.com/project/dog-repellent-ultrasonic-circuit-2-18311/

Posted: Apr 27, 2015


well i want to know is how this dog circuit work

Posted: May 23, 2015


A badly designed circuit. Turn the pot and it will blow up.

Posted: Dec 14, 2015


Great Project!

Posted: Feb 22, 2016


Nice project, yeah. But larzman make me think that if your project is not ready, maybe is not a good idea to make it public. Specially if you are too lazy to finish it. I just say because that will give a bad first impression to people.

Posted: Jul 17, 2016


Seems kind of unethical

Posted: Aug 21, 2016

Emmanuel Galleto

Hi @notengobattery the project is already finished FYI. @Katt1n sorry if it doesn't pleases you.

Posted: Aug 24, 2016

Nice project work!

Posted: Dec 14, 2016

hi emmanuel, does this thing work? God bless gabriel

Posted: Sep 13, 2017


R2 is superfluous. The capacitor voltages are WAY too low for a 9V battery. If RP3 is turned to the highest frequency, it will short pin 7 to Vcc and burn out the 555. What are all the diodes for? If you use a 9V battery with 9V connector, you can't connect it backwards. As for D2 and D3, I don't see the purpose. If that is meant to make it a square wave, it is drawn incorrectly. I hope this helps.

Posted: Sep 14, 2017


RP3 is in the wrong place. What is the point of the 63u on the output? What is the point of D1?? What is the point of having a mark:space ratio??? What is the point of R2 on a high-impedance line?? Just a dribble circuit from someone without any electronics experience.

Posted: Sep 21, 2017