555 Crriter Repellent




About: Preapering for my medical entrance exams

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

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

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

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

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

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 r1398ohit@gmail.com

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    29 Discussions

    spirit x

    2 years ago

    does the ultrasonic frequency from the repellent crack glass panes?


    2 years ago

    Does a 60 kHz will repel a mouse?


    2 years ago

    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 ????


    3 years ago

    please give me the piezo speaker requered technical details


    4 years ago on Introduction

    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 zeeshantalash@gmail.com

    2 replies

    4 years ago on Introduction

    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.


    3 replies

    Reply 4 years ago on Introduction

    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.


    Reply 4 years ago on Introduction

    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?


    4 years ago

    what type of piezo speaker I should use?



    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

    555 schematic corrected.jpg
    2 replies

    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

    555 simplest.jpg

    6 years ago on Introduction

    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.

    2 replies
    Dave KruschkeHadmahon

    Reply 5 years ago on Introduction

    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."

    Fishing Dr Morgan.jpg

    Reply 6 years ago on Introduction

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