How can you be sure of what the frightened dog will do? There are few people on this planet I'd take on a vicious dog for myself. If you walk up on an alligator, you don't poke it with a stick. If you do see someone actually getting mauled, this device will need to be extremely powerful to have any effect. Load like a gun shot. Your hearing, the victim of the mauling, and the dog's will be put at risk.

Now, most dogs bark, growl, and put on an impressive display of aggression, but seldom actually bite. Most people who get attacted, seriously mauled, not just a little nip, usually provoked it in the first place. They over reacted to the warning the dog was giving, or thought they were so vastly superior to some stupid animal...

For a hand held device as you have described, you can only hope for a dog teaser. Might as well poke it with a stick. Pepper spray would be a thousand times more effective.

 

I thought the discussion was about a device to stop a dog from peeing on a lawn. So few of the thread messages are in their original form (due to editing), I can't confirm it.

"They" don't make a sprinkler that comes on when a dog enters my lawn, it's mine. It's not operational; it was triggered by an electric eye at 1 ft. Another electric eye at 3 ft disabled it, on the assumption that the mailman and gardener would be more than 3 ft high. (Delays are required).

Neighbor with the dog has moved, so it's no longer needed. I may hook it up again, this time to a camera, for home security.

 

This thread was never about dog barking or peeing except for the many who didn't read it. Or didn't bother asking.

Incidentally, my sister project is an identical 1.5" x 3.3" pellet lined with Nordihydrocapsaicin and an ultraviolet dye. I'm still engineering the dispersal method.

To have any practical use, I need between 120db - 130db (sustained for under than 20 seconds to prevent hearing damage) which certainly seems plausible for a specialized piezo. My search for components might be moot if I can somehow confirm the existing products have this sound pressure.

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I don't remember the datasheet for an ultrasonic piezo in this thread that produces 119dB at 1m. Maybe the 400W tweeter with 400W.

I think a tiny 1.25" diameter piezo ultrasonic transducer would produce 119dB at a distance of only 10cm with a power input of 10W if it survives. An amplifier to produce 10W would need a pretty big and heavy battery.

Sound decreases in level 6dB with each doubling of distance. Humidity reduces high frequencies. Wind also "blows away" high frequencies. High frequencies are very directional.

119dB at 10cm.
113dB at 20cm.
107dB at 40cm.
101dB at 80cm.
95dB at 1.6m.
89dB at 3.3m.
83dB at 6.6m. That is about 20 feet and is not loud.

Is it worth it?

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Uncle $crooge

 

My last dog was a Rot mix, big dog. Wasn't real aggressive, just had a taste for pitbull. Once he was on the attack, only physical means could stop it (no easy task). I think they use very low frequencies to provoke each other. My dog's breathing would change, could almost hear something.

I know you don't want to hear anything but parts and circuits, but this stuff is also important to the design, otherwise its just a dangerously false sense of security, and more likely to provoke an attack. I've raised several dogs, mostly large breeds, couple considered dangerous (think that's mostly in how you raise them, never a huge problem). They are very quick, not 100% predictiable (have a few scars to prove it), and extremely strong. An animal in pain is a danger to everyone in biting distance, its defensive. Even the dog's owner isn't exempt.

I really don't know all the details of how and why some people get mauled by dogs. I'm not talking about a single nip or bite, but a full on attack. Never witness that sort of behavior in my dogs. Even when a male dog gives challenge for leadership rights, it's not about inflicting damage, but I learned how to play that game, maybe it's not so common.

Personally, counting on a gadget that makes noise isn't going to be enough to stop an attack in progress, and you really don't have time to fumble around for it. Best you can do is report a vicious animal, and get your neighbors involved. If the owner doesn't handle the animals correctly, they shouldn't have them.

 

1. Read my "keep it electrical" comment. Appearantly it didn't sink in.
2. Re-read.
3. If you aren't audio, nigel, torben, chemelec, jemch, mneary, Hero, or gramo; press ALT+LeftArrow and spare me these inane distractions.


That much dB loss huh? Yeah, barely justifies the cost in that case. It makes me wonder if the commercial stuff only works by being highly directional. If at all. I'll keep my eye on the piezo tweeters. They could still be useful in some other context. Maybe a car backup warning for dog owners or something. I'll do some more sleuthing and see if 119db has any application against less aggressive animals.

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Here are the spec's for the big piezo tweeter used in cheap old PA speakers. The frequency response graph has been heavily smoothed to make it look "smoother".
With a 64W amplifier, its sound pressure at 8m is not very loud.

Attached Thumbnails

 

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Uncle $crooge

 

A single Mosfet cannot drive a piezo transducer properly. You need the drive to be push-pull. A bridged output will effectively nearly double the supply voltage for the driver circuit. A CD4047 oscillator IC has two opposed outputs for driving a bridge.

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Uncle $crooge

 

Whether you like it or not, ethics will be part of the discussion. It really is important. Deal with it.

 

I find this thread useful because of a cat that poops in my lawn and my veg garden and my kids sand pit... there are too many stray cats, I wish I could identify the owner and drop off the poop at their front door.... anyways I want to have a motion sensor connected to this loud device so when it detects motion it annoys the cat enough it does not take the time to use my backyard as its toilet. Maybe one could use some cheap car audio amplifier to drive the tweeters and input HF square wave to the amp through a pic. Should try modulating the HF in some annoying lightning sequences and varying frequencies. Getting a good tweeter would be a starting point.

Kim

 

2/3 milk 1/3 antifreeze. Its clears up a yard / Kids sand box with a cat infestation surprisingly quick.

And its much quieter and less traceable than a 22 with bird shot!

Plus any cat owner who does get a sick cat at home cant prove it was you who supplied the antifreeze.
Kitty could have just found it anywhere while spending the night out on the town.

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oh.... The thing is I love these animals and antifreeze is torture, I had a friend who had her cat ingest some of the AF, and I have seen how both of them suffered, it is too cruel to me... and it is not the animals fault anyway. I have gotten over getting angry and upset. Me and my kids have taken it up as a challenge to protect our yard from the cats and one part of it is cleaning. This also not a one time occurrence it is ongoing for years all kinds of cats and possom and other unknown nocturnal creatures. I rather harm a human who tries to break in... which you cannot legally in California.

Anyways back to topic I have read through the net and aware of the different methods but I would like to make one that is effective in the long run and humane.

Kim

 

Why do people let their cats roam the neighbourhood all the time and mess it up?
My dog doesn't.

__________________
Uncle $crooge

 

My dog just did, and might have made some puppies too. Neighbor didn't seem to mind. Drove around for over an hour looking for him, seems he just invited himself into one of the apartments next door.

This thread is a couple of years old.

As someone who spent a while messing with trying to scare off cats with high frequency sound, can say it's a waste of time. Only effects a few cats, some get use to it and start hanging around again. Some just ignore it all together. Loud is loud, regardless of whether you can hear it, and it can still do some damage. The best cat deterrent is a large dog, cats walk past my house quickly and cautiously since I got my Labrador puppy. There is also a motion detector lawn sprinkler that soaks them pretty good.

When I was having major cat problems, it was do to over population. I had a neighbor who took in strays, but never bother to get them 'fixed', so he also had lots of kittens. Had about 29 cats+kittens for a while. Cats don't like to share their toilet, so they have to find a special place... Maybe my old neighbor moved in down the street... You should look around and see if someone is running an animal shelter on your block, might be the reason your yard is a toilet for cats, and see if they might consider getting rid of a few. A lot of places have limits on quantity of pets as well. They mean well, but aren't doing all the good they think for the cats, or the neighborhood. All those cats, also brought fleas, roaches, fire ants and rats, and probably other nastiness, besides the poop. Cats won't hunt, if they are well fed. I took 2 years to get rid of the pests, after the cat man moved, this was the first year I didn't have to fight, or catch anything in the traps.