Ultrasonic circuit

[John10b]

I’ve been asked to recommend or make a hand held ultrasonic dog deterrent. I’ve looked into it and there are plenty on the market, but with very different results and opinions that don’t give me the confidence to recommend any one.
I thought I would construct one myself, I understand that 25khz is the preferred frequency rather than 40khz?
So I was hoping if any one who has experienced the same problem or constructed one can suggest a circuit that will work and produce a decent level of output. Many thanks
John

[paulsherwin]

I don't think there's much point in building one yourself. Either the concept works or it doesn't, and who builds it won't make any difference. It all depends on what you want one for - they seem to be mostly marketed as training aids. If you're being attacked by a pitbull then it's unlikely to be deterred by a bit of ultrasonic noise.

Apparently a bag of pork scratchings thrown on the ground is a very effective distraction.

[John10b]

Thank you for your comments, I tend to agree with you Paul.
The person who asked me about the ultrasound devices has a noisy dog next door, so they were hoping by just pressing a button the dog would stop barking.
I might just knock one up and give it a try!
Cheers
John

Apparently a bag of pork scratchings thrown on the ground is a very effective distraction.

I couldn't leave a packet of same in my pocket for long!

Back on topic, a tweeter, hifi amplifier and one of the free soundcard signal generators would be useful for an experiment.

[AC/HL]

If it was powerful enough to be a deterrent from a distance you'd get complaints from other pet owners. I'd guess that if they're effective they would be widely advertised as it's a common problem in built up areas. Tricky problem to solve, our Scottie has a powerful bark for a pint pot, we just have to be considerate.

[John10b]

Yes Bill I agree, our Yorky had a very loud yap, after 18 years he is sadly no longer with us.
Unfortunately many people are not very considerate and can cause a lot of unpleasantness.
Cheers
John

[Refugee]

They have a springer spanial next door to us and when it comes out into the garden it barks until I lean over the fence and say "hello" to it then it stays quiet.
If it sees a cat it turns into a rocket

[joebog1]

I did extensive research into keeping fruit bats out of mango orchards.
An LM380 driving a $6 piezo speaker ( yes SPEAKER ) driven by four random frequency oscillators ( running "about" 20 - 25 khz , from a quad op-amp )resistive mixed also at random intensity, worked extremely well. You cannot hear it!, it was effective for bats!,
I havent tried it for dogs.

Just an idea I thought I could add to the discussion.

Joe

[Steve G4WCS]

A quick Google brings up a couple of circuits.

https://www.electroschematics.com/6/...ry-dog-chaser/

I've a couple in the the garage somewhere that use ex TV remote type transducers ( shows how long ago I made them ), driven by a CD4047 configured as an astable multivibrator.

I could power one up and point it at the dog I suppose to see if it's any good, but I would imagine to be any real deterrent you would have to go to higher power, maybe oscillator ( modulated ?) power amp, and P.A type piezo horn tweeter.

Or just buy one ready made

[Terry_VK5TM]

I made one years ago using a Piezo tweeter (from an old magazine article), didn't seem particularly effective.

You might also want to make the frequency adjustable, as some dogs will respond to one frequency while another won't.

[Al (astral highway)]

Originally Posted by John10b

I’ve been asked to recommend or make a hand held ultrasonic dog deterrent.

Hello John,

What's the purpose of this, I mean, specifically how is it to be used? I can't imagine why someone would want to 'deter' dogs unless they are particularly phobic of being attacked at random.

In which case, the thing will be 'transmitting' all the time at random. It doesn't sound very sociable!

40KHz is a common frequency for ultrasonic baths. You might want to search the circuit or pop one open to check the power side of things.

[PsychMan]

A neighbour near me has 2 such devices installed in the lawn, they are set off by motion when I pass them walking my 2 dogs. I can hear them, but my hearing is quite good at the top end and I don't know what frequency they operate at.

My dogs don't seem to care about them whatsoever, so not really sure what purpose they serve.

Maybe they work better for foxes? Or maybe they're just a waste of money

[John10b]

Thank you all for your various comments and suggestions.
To answer some of your comments.
The lady in question enjoys sitting in her small garden, unfortunately her neighbors have just got a dog (don’t know which breed) which seems to bark at the slightest thing. She was hoping that by just pressing a button it would deter the dog from barking.
I’ve no experience in such devices so that is why I asked the question, yes there are plenty of circuits and components out there and ready made units, but the reviews vary dramatically. So I was hoping that someone with actual knowledge of the problem and the devices could provide some useful practical information.
From what I’ve gleaned 25khz is preferred to 40khz, and the suggestion of having it to vary around 25khz seems sensible, hope that makes sense.
Cheers
John

[Radio Wrangler]

Something which disturbs the dog is more likely to start it barking, I would have thought.

David

[Al (astral highway)]

I agree with David.

Dogs live in an auditory and olfactory world and have acute sensitivity to sound. This will be like noise torture. Since dogs are unable to communicate distress other than by barking, more barking is what your neighbour will produce!

Perhaps she should make friends with the dog, it is a pack animal and needs company (maybe not given by the owners). Once a chum they tend to respect you as the "upper hand" and calm down. Cats are the other way round, alone quiet, with another one or few lots of noise. I find that if I go out for a walk having parked my motorcycle somewhere scenic and having motorcycle gear on (unwashed and probably a bit smelly, the gear not me) dogs bound up and have a good sniff, a stroke is always appreciated. Never been bitten I must be a dog magnet.

[John10b]

Thank you all, after further discussions the matter has been put on hold for the foreseeable, once again thank you.
Cheers
John

[David G4EBT]

Originally Posted by PsychMan

A neighbour near me has 2 such devices installed in the lawn, they are set off by motion when I pass them walking my 2 dogs. I can hear them, but my hearing is quite good at the top end and I don't know what frequency they operate at.

My dogs don't seem to care about them whatsoever, so not really sure what purpose they serve.

Maybe they work better for foxes? Or maybe they're just a waste of money

I think they're most likely to be cat deterrents. We have flower beds at the front of our house which local cats decided to adopt as their toilet some time ago. I put a couple of ultrasonic motion detectors in the flower beds maybe five years ago and it solved the problem. The batteries last for ages as the device only comes on when it detects motion - it lights up blue to show that it's working.

(If dogs bark incessantly, the local Council will take action with/against the owner).

[Refugee]

I have found that a reduced power electric fence works on veg seedling beds.
If bright red insulators are fitted they alone work as a visible deterrent for some distance.
Even butchers string between sticks also works once the initial training is done with an early bed with fake rows in it.
I usually put the lines in and observe the scratch marks where they go along looking for the seedlings so that they can stamp them back into the ground.
It is usually a minority of cats that do it and also kill baby birds.
I managed to get one owner to admit that it was their cat with the help of CCTV.
The owner agrees that it had earned itself a clip around the ear like the ones earned for pulling the threads on soft furnishings.

[ms660]

I'd be careful if attempting to shut someone else's dog up, things might turn violent.

Lawrence.