Mosquito Repellent

The summer this year is too hot, the heat is not really a problem but mosquitoes ...! ,especially i camping.

So after i tried some solutions i got the idea to make an electronic mosquito repellent that i can take with me wherever i go. this circuit is just a transistor multivibrator that generates high frequency sound ,and mosquitoes don't like this sound.

I am not gonna use a PCB i will just solder components together to make it a simple and cheap

Update : here is the Kicad project + (the PCB , the schematic , the components view ) in PDF

Mosquito repellent.rar

Step 1: Components

1. two BC548 transistors or equivalent
2. two 100k resistors radio shack link
3. two 1.5k resistors radio shack link
4. one 4.7k resistor radio shack link
5. one 2nF ceramic capacitor radio shack link
6. one 560pF capacitor radio shack link
7. 5mm Red led radio shack link
8. Toggle switch radio shack link
9. 9v battery radio shack link
10. 9v battery snap connector radio shack link
11. Piezo element radio shack link
12. a small project enclosure radio shack link
13. some wire

This components i salvaged them from my older projects ,but i put links to Radio Sack

Step 2: Tools

1. Cutting plier
2. Needle nose plier
3. Solder iron
4. Some solder
5. Philips screwdriver
6. Hot or super glue

Step 3: Circuit Soldring

solder the components in order like in the pictures

1. Bend the collector and base pin of each transistor
2. Solder the emitter pins together
3. Solder the 560 capacitor then 2nf one solder the two 100k resistances then the other 1.5k
4. bend the free pins of 4 resistance and so

Step 4: Preparation

1. Make a hole for the toggle switch with the soldering iron then enlarge with the screwdriver
2. Screw the switch in place

1. Solder the 4.7 resistor to the positive pin of the led
2. Make a side hole on the box with the soldering iron for the led
3. Solder the led current limiting resistance to one one switch pin

1. Solder two wires to the Piezo element ,positive pin is the middle disk
2. Make a small hole on the lop next to the switch for the Piezo element wires
3. Insert the wires in the hole and glue the Piezo element to the top

1. Solder the red wire of the snap connector to the other pin of the toggle switch
2. Solder the black wire to the negative pin of the LED

Step 5: Final Assembly & Testing

1. Solder the common pin of the resistors to the pin of the toggle where the led limiting resistance is soldered
2. Solder a wire from the emitters to the negative pin of the led
3. Now solder the two piezo element wires ,between the positive and the 2nf capacitor junction with the collector

First testing:

1. Connect the 9v battery
2. Turn on the switch , the led should light
3. If you don't hear nothing put in parallel a capacitor approx 100nf with the 560pf capacitor ,if you hear a buzz everything is alright ,you're just not sensible to the high frequency
4. Put the battery in place and close the box

final word:

If you are sensible to the high frequency this can drives you nuts

Step 6:

Comments

[HETG]

Can you explain we working in of
your circuit

[vanditpatel2000]

Please Explain me it's working

[PirateKittyK]

All these devices are supposed to imitate wing beatings of dragon flies.
Well, dragon flies make sounds in the 30KHz to 70KHz range. You do the math.

[Yonatan24]

This doesn't really work, It was proven scientifically that these noise repellents don't work:

http://www.bbc.com/news/magazine-20669080

[Aleator777]

Now to deploy these in swamps everywhere! Mosquitos be-gone!

[raven.sirius]

and teenagers!

[علیرضاق]

I MADE IT
I couldn't find 2nf capacitor so I had to use 2.2nf
When I connect the circuit to the 9v battery I can hear the noise (buzz) without using 100n capacitor!!!
what should I do?
please help me
dirt for bad English

[amgworkshop]

It's okay to use the 2,2nf instead , and you should hear a high pitch sound.
The 100nf capacitor is just for the test to make sure the circuit is working.

[smooney2]

This does not work .. Mosquitos are neither attracted or repelled by ultra sound in the 20-70 KHz range or sound generators capable of a wide range of frequencies . These frequency generators are a marketing ploy aimed at people who are not wanting to use pesticides .. I work in the mosquito field .. I wish they did work it would make my job easier

[DangerousTim]

what kind of oscillator is this? How would you calculate the frequency?

[Dave Kruschke]

First thing, the details of your instructable are as clear and understandable as any instructable I've ever seen.

But do let us know the results of any testing you do with actual mosquitoes. I've read that mosquitoes don't even hear ultrasonic frequencies. Instead, male and female mosquitoes keep in touch with each other using audio frequencies around 400 Hz, NOT 40,000 Hz. Moreover, I've read that there have been more than a couple of tests of ultrasonic mosquito repellers that revealed that these repellers didn't work at all.

However, there is hope for your device as I've read that some shopkeepers in Dear Olde England have deployed devices like yours set to about 16000 Hz with the purpose of repelling unwanted teenagers who can hear these frequencies. Check out Howard Stapleton - teenager repellers. Note: the use of these devices has been challenged by some EU agencies that consider these devices "cruel to young humans and other creatures, treating them as unwanted birds or insects."

[stubbsonic]

I'm like flavor-blasted Doritos to mosquitos. They bite me once, then they go find all their friends and come back for more. And DEET really is the only thing that works for me.

Have you tried your high-frequency device "in the field"?

I'm skeptical as to how well it will work in more intense circumstances.

[amgworkshop]

yes i thinks it's working .but i can't stand those ultrasonics.

maybe i will increase the frequency or lower the operating voltage

[baecker03]

there are all sorts of pest control devices using ultrasonic frequencies. like the above poster, unsure of how well it would work in this case.

[Bashey]

Is it a 2nf or a 2.2 nf capacitor? 'cause i can't find some 2.2nf capacitors in my favorite electronic store.

Does operate on diferent voltages too?

And can i use some ultrasonic transmitter either (instead of the Piezo speakers)

very nice Project by the way! :)

[amgworkshop]

it's 2nf ,yes it does operate on different voltage from 1.5v to the max voltage of the piezo buzzer and the transistors . i think you can use an ultrasonic transducer if that's what you mean.

thanks Bashey