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Author Topic: Rats repellent circuit - ultrasonic sound generator  (Read 6823 times)
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Hi folks,

I've got a bit problem with rats, they are destroying my garden. I don't want to kill them, just keep them away.   So, I would like to build a rats repellent circuit. I've read a lot on the topic; some say it works, some say it's pure fantasy. I'll like to try  smiley

I found different circuit schemas around the web (like http://chill-blogspot.blogspot.it/2009/07/ultrasonic-pest-repeller.html) but I would like to solve the problem using Arduino.

Requirements:

- the frequency should range continuosly from 30 kHz to 50 kHz
- it must be powerful, because it should protect a big garden

It's that possible? Anyone has already tried that?

Thanks a lot.

Matteo
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some say it works, some say it's pure fantasy.
Works about as well as the elephant repellent whistles around my garden.

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- the frequency should range continuosly from 30 kHz to 50 kHz
See if the tone library goes that high.

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- it must be powerful, because it should protect a big garden
Sound waves take energy to create. The Arduino doesn't have that much. You'll need either an amplifier or a cat. Cats are probably cheaper.
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You could build a device and it could be controlled by an Arduino, though you could probably make a circuit to scan up and down the frequency range without needing the Arduino.

Whether or not it will work is a different question, I doubt it. If you were hungry how much noise would it take to drive you away from food? I don't think you will be able to generate the volume you require and, even if it works initially, the rats will probably adjust to the noise. Rats are supposed to be smart. If you are going to have a go then rather than scanning smoothly through a range you might be better trying random bursts to startle them.

Maybe you could catch one and do some experiments before going wholesale for a solution.
If you have enough rats to destroy a big garden you should be thinking about shooting them or trapping them.
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I don't think you connected the grounds, Dave.
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Or you could trap some bankers and experiment on them instead.
That would be a more humane solution.
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That would be a more humane solution.
Or lawyers.
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Oh no. I am only just back on the forum after an absence and already I think this is heading for "bar sport";
You could get the rats to experiment on the bankers and lawyers!

Here is some interesting stuff
http://en.wikipedia.org/wiki/Sound_from_ultrasound

You would have to pump out a lot of energy to fill a large garden with sound, but perhaps you could use a directional beam - that would require motion detection and aiming though.
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That would be a more humane solution.
Or lawyers.

Plus, you can get lawyers and bankers to do things that rats won't. For the rats, I'd much prefer .22 long rifles or even .22 shorts.
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This is amusing, though it relates to deer not rats;
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I like the comment that propane gas exploders and strobe lights can be annoying to humans. There is also a comment that there is no evidence that deer can hear ultrasonic devices attached to vehicles. I was sceptical about these devices on cars, but I fitted a pair to my vehicle and I am beginning to be converted (they are passive devices the flow of air when the car moves is supposed to generate ultrasound).

On several occasions, including this morning, I have noticed deer apparently hearing the approaching car at long range then making off fairly quietly into the woods. Often in the past, without the device, deer have been startled and bolted onto the road. It could be chance, but I am coming round to the idea it works.

With the rats though I am beginning to like the idea less and less. I doubt it will keep them away but it may affect other wildlife like bats and owls - and maybe deer.

Where are all these rats coming from, have you had a good look around the area?

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First of all, many thanks for all your thoughts and ideas smiley

<offtopic>
Here in Italy, right now, we would like to do dangerous tests with our politicians... the sound from ultrasound thing could be a good idea to start with  smiley-cool
</offtopic>

I think I'll buy an Arduino kit and start to play with the sound module. Is the rev3 good for I need to do?

Quote from: radman
Where are all these rats coming from, have you had a good look around the area?

Yes I have: the problem is that all around my garden there is absolutely nothing to eat. The first year on which I planted something, there were no rats. Then they start to increase year by year. Interesting thing about the deers!
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The motion may work, just detect motion then a loud varying burst suddenly, instead of continuous
or maybe some high voltage spikes/fence? Lol 20kv should give them a jump
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So it must be my cat that is keeping the Elephants away from the garden since I don't have any of those whistles.

Don
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Elephants are almost deaf, the big ears are for cooling and they keep out most of the sound.
It could be that your cat is being lazy and not dealing with mice. Elephants are afraid of mice so that might explain why you don't have any.
If you don't believe elephants are afraid of mice look up Mythbusters on youtube.
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The only thing useful i found was: "Just generate a rectangle signal with a frequency bigger than 20kHz and amplify it by power transistors."

the question i have is how to make the rectangle signal with arduino?
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The only thing useful i found was: "Just generate a rectangle signal with a frequency bigger than 20kHz and amplify it by power transistors."

the question i have is how to make the rectangle signal with Arduino?

Actually, a square wave is as I understand it, precisely what the "tone" function in the Arduino IDE generates.

The shape of the waveform is in this case, quite irrelevant because a square wave has only odd order harmonics, so the first overtone of 20 kHz is in fact, 60 kHz and beyond the range specified, so a square wave and sine wave (or any other symmetric waveshape) have the same effect.
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