Introduction: 555 Crriter Repellent

Picture of 555 Crriter Repellent

Many of the citizen scientists all around the world might have faced this problem that thier sunflower or any other plant is eaten up by critters before it even fully grows , so I have come up with a very simple solution to this problem , expose the critters to high frequency noise which they wouldent be able to tolereate and will not get near your plant .

This critter repellant is basically a high frequency emmiter ( 61 Khz ) based on the 555 timer . The 555 Timer is a powerful chip for low cost projects by adjusting the values of components that you will be connecting to it you can make it emit various frequencies . The Timer in our circuit will function in astable mode which will put out a continious stream of stream of rectangular pulses having a specified frequency. 

This instructable will explain some basics on how it works , the parts needed , how to prototype the circuit on a breadboard , and finally soldering everything into place.

Step 1: Parts & Tools

Picture of Parts & Tools

Parts :
~ LM555 Timer - Mouser Electronics 
~ 10 k Ohm Resistor - Mouser Electronics
~ 6.8 k Ohm Resistor - Mouser Electronics
~ 1nf Ceramic Capacitor - Mouser Electronics
~ 1 uf Ceramic Capacitor - Mouser Electronics
~ Piezo Speaker - Local Electronic Store
~ 9v Battery - Local Electronic Store
~ 8 Pin DIL Socket - Local Electronic Store
~ 9v Battery Snap - Local Electronic Store

Tools :
~ Soldering Iron - Mouser Electronics
~ Solder Wire Lead Free - Mouser Electronics
~ BreadBoard - Mouser Electronics
~ ProtoBoard - Mouser Electronics
~ Single Strand Wires ( Used As Jumpers ) - Mouser Electronics

NOTE: Use A High Frequency Piezo Speaker Which Can Handle A Frequency Of 65Khz

The Price Of All The Parts Before Shipping Is 5 $ . Assuming That You Have All The Tools Already On Hand.

Step 2: Prototype the Circuit

Picture of Prototype the Circuit

This circuit is pretty straight foreward ,it consists of two resistors , two capacitors , a 555 Timer , a piezo buzzer and a 9v battery . The circuit works around the very versatile 555 timer IC , the values of the surrounding components are set in such a way that it produces a frequency of 61khz . They were calculated using the forumula attached as the last image , if you find it difficult then you can use this calculator . The Timer in our circuit will function in astable mode which will put out a continious stream of stream of rectangular pulses having a specified frequency . The circuit is pretty straight foreward the 10 k resistor is connected to pin 7 and the other end to gnd , pin 8 is connected to +9v , pin 1 to -9v , pin 2 and pin 6 are connected togather , 6.8k resistor is connected to pin 7 and its other end is connected to pin 6 , 1nf capacitor is connected to pin 6 and the other end to gnd , the buzzer is connected to pin 3 via a 1uf capacitor . The schematic is attached to the last image . It was made using Fritzing

Step 3: Testing the Circuit

Picture of Testing the Circuit

To test the circuit you need a frequency counter or a ossiloscope you cannot just hear the sound and make out that if the circuit is working or not as the sound produced of high frequency and you cannot hear it . I did not have any frequency counter on hand so I made a quick and easy frequency counter using the arduino you can find it here . Here are some screenshots of the frequencies that the circuit produces.

Step 4: Soldering

Picture of Soldering

Now that you have built the circuit on a breadboard and tested it lets make the circuit permanent and solder it.If you have no experience of soldering consult this guide.You should always use the lead free solder as leaded could be harmful.Maintain safety while ,soldering use gloves and safety glasses use proper stand to keep you soldering iron as it is very hot and can harm you. You can use single strand wire to make connections as I did . You will require a small piece of protoboard as this circuit is very small too . Use 8 pin DIP socket to keep your 555 Timer safe . As you can see in the pictures that I am not very good at soldering.

Step 5: All Done

Picture of All Done

Hope this project inspires further experimentation. The 555 Timer is extremly versatile and do not need many external components as othe IC's do . This is just one of many simple projects which can be constructed using the 555 Timer. Keep pondering!.Dont forget to follow mores comming up. .For any queries leave a comment below,PM me or contact me heres my E-mail ID


Jsoa (author)2017-10-15

Does this repellent work for raccoons?

And can i make it from my old repeller Hoont Ultrasonic Motion Activated Repeller?

Read more information about him on the

spirit x (author)2017-05-09

does the ultrasonic frequency from the repellent crack glass panes?

MalharC (author)2016-11-26

Does a 60 kHz will repel a mouse?

MalharC (author)2016-11-24

I have made it but can hear the sound ! that means it is not ultrasonic ! :(

Can u help how to fix it?

and also how to use the formula given ????

TilakR4 (author)2016-06-13

please give me the piezo speaker requered technical details

Zeeshana5 (author)2015-04-29

Dear Farahishak ,,use 555 astable multivibrator ,, use r1, 500k ohm, r2 ( 10k to 1M ohm) and 68pf capaicator ,, the frequency range of 8khz to 41khz with 60 to 99% duty cycle best repellent range for mosquito fly, bee, cat, dogs cocroch etc pest,, the piezo buzzer can you order online in ( eveelectronics ) web page...for any further help

farahishak (author)Zeeshana52015-05-13

tq for your help zeeshana5. which speaker is effective? piezo speaker or tweeter speaker?

Zeeshana5 (author)farahishak2015-05-17

40khz piezo buzzer

farahishak (author)2015-04-15

1) this repellent is suitable for wht animal? or just for insects?

2) the piezo buzzer is like normal speaker is it? this repellent produce sound? the human can hear the sound or not?

3) hoe can i maximize the amplitude. i mean that i want to maximize the coverage but at the constant frequency level??

i really need your help. because i must do simple project actually my project is wild boar repellent.


Zatara11 (author)farahishak2015-04-21

Since it's putting out 61kHz this circuit will work great for rats.

The sound that the piezo buzzer puts out won't be heard by humans because our hearing range stops at about 20kHz. Even at 20kHz, the sound is very weak to humans. This will also be a safe circuit to have around any common pets. If you have an exotic animal you'll need to find out it's hearing range.

farahishak (author)Zatara112015-04-24

how can i increase the amplitude of the frequency?? i want constant frequency 40khz and high amplitude?? i have success build 40khz circuit but i want high amplitude?

farahishak (author)Zatara112015-04-21

tq for helping me. zatara11

freedenair (author)2014-11-03

what type of piezo speaker I should use?

Dave Kruschke (author)2014-02-24


In your instructable here you reference another site that allows one to calculate frequency given two resistors and one capacitor. This site also reveals the correct, workable schematic for your device. But both your schematic and your "Fritzing" show the 10k resistor at point X (on my schematic below) going to 0V instead of 9V as also shown on the other site you referenced. The device built using the schematic below oscillated at a measured 61 kHz using a variable resistor (pot) set to 5.9k (rather than 6.8k as shown in the schematic) - a very minor difference. But again, the 10k resistor must go to +9V not -9V.

I'm a little surprised that you measured 65536 as shown on your Instructable as 65536 is exactly 2 raised to the 16th power.

The tip of your soldering iron in your picture looks way, way too blunt to solder up a proto board. I always file my soldering iron tips to a sharp, tapered point, even if doing this shortens the life of the tip.

Finally, and perhaps least important, is the fact that ultrasonic devices have been shown in the US to not work at all for deterring mosquitoes. The wings of the female mosquito vibrate at about 400 Hz while the male mosquito wings vibrate at about 600 Hz. Both mosquitoes listen in for each other at around 1200 Hz, the third harmonic for the female and the second harmonic for the male. These mosquitoes don't listen to any ultrasonic frequencies produced by bats and this is why these device don't repel mosquitoes. And the large wings of the dreaded dragon fly vibrate at a much lower frequency than the female mosquito and are not known to be heard by mosquitoes...

Dave Kruschke

PS; Please click on the above schematic to see the full schematic!

PS, again, some additional comments:

First, a simpler 555 device with fewer parts
is presented here - see schematic below. Notice how the frequency changes with
the battery voltage? Not a horrible problem but something to keep in mind. In
fact, a decreasing voltage that causes a decreasing frequency might offset any
possible "notch effect" raised by another reviewer here.

For my device, I deliberately used common part
values for the resistor and the capacitors. The purpose of using the larger
capacitor is to be able to test the circuit when desired as the device makes an
audible sound to humans when the larger capacitor is used. This capacitor could
be used with a switch to "switch in" to test for an audible sound,
indicating that "all is well" with the device.

When I went on and on about mosquitoes, I
falsely assumed that mosquitoes were being target here. But now I am aware that
other animals (rodents, perhaps) were being target such as those that eat crops
intended for people. I looked up some hearing frequencies for various creatures
and found:

Humans; 20 Hz to 20 kHz, Cats; 55 Hz to 79
kHz, Dogs; 40 Hz to 44 kHz, Bats (ugh); 15 kHz to 90 kHz (typical), mice; 1 kHz
to 70 kHz (baby mouse in distress = 40 kHz) and finally Birds of the Aire; 1
kHz to 4 kHz plus.

If anyone deploys one of these 555 devices
amongst crops, it would be interesting for sure to see what the effective
radius is (if any)....

Dave Kruschke

Hadmahon (author)2013-01-21

I like this idea! Anyway, the first thought that came to my head was: Could it harm bats somehow? That wouldn't be exactly cool.

Dave Kruschke (author)Hadmahon2014-02-26

I wouldn't lose any sleep over bats. In the Northern US, one out of every 100 bats carries rabies and people that get it die a horrible death. So I am not sympathetic to those that harbour bats because they think they are cute or "beneficial."

Bot1398 (author)Hadmahon2013-01-21

This Device Wouldent harm any any animal in any way it will just keep it away from the place where you keep the device

Raphango (author)2013-10-29

Great project!

f2364738 (author)2013-06-15

the cuircuit image file for the yEd software (my post below)is at
if i have made a mistake please correct it.

f2364738 (author)2013-06-15
more info

variable resistor from 1-10k ohms please. she says no have. can we have an image of this beast please. what is an audible frequency and corresponding ohm resister to test the speaker? more info on the piezo speaker would be nice as this is also proving hard to get. PS i am in the third world.

pyrohaz (author)2013-01-28

Brilliant instructable! Voted, also on the VFO thing, you could do that using two 555 timers, something like:

Instead of having the 10k resistor from pin 3 though, take it from pin2 and the frequency will vary between a high and a low point (dependant on the value of control voltage) if you make the 10uF capacitor on the left timer really large like 1000uF, the sweep will take much longer to do.

Still! Awesome instructable :D

J-Five (author)2013-01-20

I agree Genuis, and on the last page was that Spongebob?

Bot1398 (author)J-Five2013-01-20

No , Its Not exactly a spongbob I got that image somwhere on google images and then I edited it

J-Five (author)Bot13982013-01-21

But still it's good use of electronics

dc-labs (author)2013-01-20

Great stuff!

I know this works based on personal experience.

When I was a lad I used to experiment with 555's making audio frequency oscillators. One time I had a tweeter attached and was sweeping the frequency range. I didn't realize until the frequency went really high that there was a mouse behind my bookshelf. When I swept the high-end, the mouse was clearly agitated. I could hear it scrambling, trying to climb up the back of my bookshelf. The sound was driving it nuts!

My understanding is that rodents will develop "notch hearing" if the frequency is kept the same. Any ideas on creating a VFO for this design so as to automatically sweep the frequency?

Bot1398 (author)dc-labs2013-01-20

To change the frequency you can replace 6.8k Ohm resistor with a Variable resistor . You would have to rotate the knob every few days and it will not be automatic .

GorillazMiko (author)2013-01-19


About This Instructable




Bio: Preapering for my medical entrance exams
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