Projects: LM555 Mosquito Pester


My problem started when my girlfriend began complaining about mosquitoes ruining her life every night . I know mosquito sprays will just drive those beast away for sometime then after a while they’ll begin to pest your night again so I suggested she should try using “katol”. It’s a normal thing for my girlfriend whenever I suggest a solution for her problem that she’ll always have a reasons why she wouldn’t agree with my suggestions. She said “katol” might cause fire (which I agree). Then I suggested she use electronic mosquito repellant, as always she’ll complain its expensive and high maintenance, mosquito net would make her uncomfortable. I suggested a few more until I ran out of solutions that could make her satisfied.

Then it came to my mind to design a Mosquito Pester (biological way of taking revenge over those pests). When I was a student I built a project similar to this one based on transistor astable oscillators. Surprisingly, she agreed.

Using the same principle as with my original project I designed the 555 based device to lessen the complexity and increase the reliability of the circuit.


Schematic Diagram:

Below is the schematic (without the ceramic transducer) of the circuit I made, my objective when I designed it was to have an output frequency as close as 5khz without using series or parallel combination of components and use only standard value components.


Circuit Description:

The circuit is based on a 555 timer configured as an astable oscillator that provides a steady output frequency.

The circuit works by imitating the sound produced by male mosquitoes which is around 5kHz in frequency. Studies have shown that female mosquitoes evade their male counterpart like hell when they are pregnant. And we’re lucky that only pregnant female mosquitoes bite us because they use our blood for reproduction.



I ran a few simulations to see how well the circuit would do and did some fine tuning of the values using standard component (5% tolerance) until I get a frequency closest to 5kHz.

Transient Simulation

Simulations at 5.104kHz

On my simulations I managed to obtain a frequency of 5.104kHz by fine tuning the values.



I anticipated that the circuit would produce a loud noise since it is supplied by 9V so included a trimmer resistor to be able to adjust the volume of the circuit.

Mosquito Pester and Schematic

A switch was also included to save battery because we would not need it running when people are not around. It must also be periodically turned off so mosquitoes wouldn’t realize they are being fooled (actually they wont, but they will learn to adapt with the noise).

The circuit was constructed on a small prototyping PCB. After construction, the actual frequency was measured and found to be around 4.75kHz. It was a big offset to the desired frequency since I did not considered worst case analysis due to tolerance on my simulations. Never the less, my girlfriend was happy that it actually worked.

Mosquito Pester Waveform

Bill of Materials:

Circuit Code



Prototyping PCB

Php 10.00

9V Battery Clip

Php 3.75

Ceramic Transducer

Php 10.00


SPST Switch

Php 20.50


9V Battery (Eveready)

Php 62.00



Php 10.00


1K, 1/4W, Resistor

Php 0.25


4.7K, 1/4W, Resistor

Php 0.25


10K, Trimmer Resistor

Php 25.00


10nF, Capacitor**

Php 1.00


27nF, Capacitor**

Php 1.00

Total Price:***

Php 143.75

* Prices are true as of 20090805 and may vary depending on vendor and location

** Capacitors may be ceramic or mylar

*** Total Price does not include the price of the tools that will be used and other constructing materials like solders and wires


~ by glutnix_neo on September 12, 2009.

58 Responses to “Projects: LM555 Mosquito Pester”

  1. nice invention………

  2. san nakalagay ung tranducer at trimming resistor sa diagram?

    • sorry for my diagram, the transducer and the trimmer resistor are connected on pin3(Output), more details on this can be found at Construction section (look at the schematic on paper),of this same post.

  3. ang galing

  4. ala ka bang computations about the maximium n minimum freq? tas duty cycle?

    • I used software(555 designer) to quickly estimate the component values. For the formula you may use the formula found at the LM555 datasheet. I set the frequency as near as possible to 5khz, duty cycle wouldn’t matter much but I kept it close to 50%.

      To know the effect of component tolerances to the output frequency I suggest you perform Monte Carlo analysis but you can always do the old “Trial and Error” trick… 😀

  5. By the way an improvement I’m planning to do is to make it more energy efficient, choosing resistors with larger values and capacitors with lower values should improve it. Playing a little with the duty cycle should cause improvements also.

  6. may nabili akong kit nito sa deeco. it worth 45 php. mga sir, pagnagsolder ako umiinit ung mga resistor, masisira kaya yun? d ko pa napapagana ung akin. hirap magsolder. kainis. bbli ako ng bagong soldering iron. please reply

    • eto ba yung transistor lang ang laman? ano value ng resistors? ano supply voltage mo?
      tingin ko abnormal na maginit yung resistors, baka mataas ang supply voltage mo.

    • may nbili din aq nyan s deeco. ung transistor type. successful ung pgkakakbit q. ang kso prang d rin nkakapaalis ng lamok e. lkas sna ng tunog. wla nmang ni isang pyesa umiinit. nghahanap po uli aq ng pnibagong circuit. 1.5 v lng po supply nun.

  7. yep. sa deeco ko binili. dalawang transistors. ewan ko nga kung pano gawin e. nahinang ko na, di ko alam epekto nun. sir tell me kung ano mangyayari sa lamok? at pano gamitin un? try ko gawin itong sa iyo. sa lunes na deadline ng sken.

  8. kuya kuya… ano b ung triangle sa diagram?… wat kind of item is dat…?? wer only rookies in making electronic devices eh.. ahahah T_T

  9. pre,may maririnig ba ko pra malamng gmgna? gnwa kc nmen wla kmeng mrinig o khit vibrtion mn lng dun s transducer,pareply nmn ASAP XV

  10. mukang pangit pa ata ung nabibili sa deeco, may balak pa naman sana akong bumili…
    i’ll try this one perao sana may formal diagram ka maliban ung na sa construction section.
    Thanks sa project mo pre!
    Hope mapagana ko hahaha 😀

  11. hey… nakabili din ako dati nyan sa deeco. nagawa ko at gumana naman siya. 45 lang yun dati pero ngaun 55 na.

    • oo nga 55 na kakabili ko lang last few days..ask q lng sna kng wala ka pinalitan na mga components dun sa kit para gumana.. yung mismo mga components sa kit pu ba ung ginamit mo?? tnx for ur reply ^_^

  12. hi, we’ll gonna try this project, hope magwork,,,

  13. Gnung battery po ba yung kailangan naming gamitin?

    • if you changed the batteries maaring magkaron ng shift on frequencies but you can design one using as low as 5V using the same circuit but could be different values.

  14. sir, what is the principle of this project as you said on the 3rd paragraph of your abstract…? i will propose this project to my group. 🙂

  15. ah….nakita ko na din itong ganito sa isang issue ng alexan….

    • yes I think I already mentioned that on my post, the difference is I’m using a 555 IC and not a discreet transistors.

  16. ganu kalayo ung distance na kaya nyang irepel ung mga mosquito? reply po asap

  17. may high pitched sound?? edi maririnig ng taong gumamit nyan ung sound?? maingay?

    • same as paano mo naririnig yung tunog ng mosquitos, (-: Ang if you can read schematic diagrams, you’ll see I added a potentiometer so you can adjust the volume but of course it will reduce the effective range of it.

  18. project nmin yan ngayun.

  19. mga sir nakabili din ako ng kit sa deeco sa may raon. maliit masyado ung ceramic capacitor. ung sakin nabasag ung kalahati nung isang capacitor ko. makaka affect ba un? ayaw kasi gumana e nahinang ko na and madali ng naman ung kit. pahelp po mga sirs. thanks!

  20. try nyo muna ang circuit kung magwork try to download PROTEUS, pcb maker yan na software, just install sa pc, it worked for me, i tried to build the circuit using the software at gumagana xa, i even tried replacing the value of resistor, maririnig mo yung tunog, kasi tumutunog xa sa speaker ng pc mo….

  21. kuya pwede bang makupya ang study mo? kasi naghahanap ako ng title for my thesis, ehh wala pa poh akung na isip na title, pwede poh ba itong project mo ang gawin kung thesis? send ka lang poh ng e-mail if anu reaction mo, kasi i was amazed by your project, problema kasi din dito sa amin ang mga lamok… ito pala e-mail ko poh

  22. is there any substitute to capacitor with a value of pF,theres no available nF in our place?

  23. is that capacitor a non-electrolitic?need your reply..i just made it but not correct value of capacitor..i think its incorrect because i just here a clicking sound wen i test it..hahaha

    • I prefer non-electrolytic ceramic capacitor but it should work on electrolytic as well.pico is x10^-12, nano is x10^-9, it’s just a matter of conversion. to convert nano to pico you simply multiply it to 1000, because 1nF is equal to 1000pF.

  24. ayoss ahh..magawa nga din nyan..

  25. try q to…..project din kc amin..

  26. ano po ba ang prenoproduced ng device na yan para mataboy ang lamok?

  27. gano po kalayo yung range nung sound

  28. gagawin namin yn sa major namin pero 100pesos lang ang budget..maganda yan para walang magkadengue..

  29. Sir. Ano if we use a different capacitor and resistor maaapektuhan po ba ung Volts ng ilalagay naming battery? Please Reply Sir. 🙂

    • maapektuhan ng different value ng resistor or capacitor and output frequency, you can do simulations like I did. or simply use a tool (android apps perhaps) to compute for the output frequency of the 555 timer

  30. Good Day Sir! Pde po bang humingi ng iyong recommendations about sa project na ito? Nais po namin itong E inovate at gamitin ito sa aming I.P sa school. Please Reply. Tnx. 😉

  31. Kasama po kami ni Jec’S sir. 🙂

  32. Good Day Sir! Pde po bang humingi ng iyong recommendations about sa project na ito? Nais po namin itong E inovate at gamitin ito sa aming I.P sa school. Please Reply. Tnx. 😉 😉

  33. Good day sir:) ..
    Nais ko pong malaman ang iyong ga suggeations at recommendations sa proj ksi nais ko pong i propose ito sa I.P nmin

  34. Good day sir. nais ko pong malaman ang iyong mga suggestions at recommendations na ma i innovate namin sa project na ito.. Need ko po asap kasi para sa aming I.P salamat po sir.

  35. Sir.. Pde po bang humingi ng iyong suggestions or recommendations tungkol sa mosquito pester na project mo? Plano kaC naming gamitin ito sa
    Investigative Project namin. Please reply. Tnx. 😉

    • One thing I noticed, the effectiveness of the frequency varies sa certain specie ng mosquito and that after sometime humihina ang effectiveness nito. What I usually do is to vary the interval na naka-ON sya, meaning hindi ko palaging ginagamit para hindi maiimmune ang mga lamok, try to experiment din kung ganun nga ang response ng mga lamok, based sa observation ko lang yung(gut feel kumbaga)

  36. pwede po bang taasan po yung tunog na napoprodure niya para mataboy din yung ibang insect katulad ng mga insect na nakasisira sa mga crops?

    • Pwede naman but remember audible din sa tao ang tunog na napoproduce nito so it could be annoying sa iba.

      • paalam po ako sainyo ginamit po namin reference yung proj. niyo para sa proj. proposal namin pero diangdagdagn namn po. salmat po 🙂

  37. wow astig naman tong prototype mu. Tagal m na to nagawa since Aug/2009 pa pero ngaun lng to nakita then ngka interest gamitin. How would you come up na 555 timer ang gamitin instead of transistor? And thank you dito sa blog mo.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s

%d bloggers like this: