20kHz signal generator amplified to 400 watts dog alarm?

[gary350]

I have to watch my step when I walk in my yard dogs in the neighbor hood run loose after dark and take a dump in my yard. I know dogs can hear higher frequency than people so I have this idea to use a signal generator, motion detector, 400 watt amp to scare the dogs away. I think people can only hear about 17kHz so no one should be able to here 20kHz when it blasts the dogs after dark. I wonder if this will scare dogs away?

 

[Ian Rogers]

Dog whistles are 23 - 54 khz according to wiki...

 

[alec_t]

....and if dogs have been trained to 'come here' when they hear a whistle, you may attract rather than repel them

 

[unclejed613]

400 watts worth of amplifier wouldn't be difficult, but 400 watts worth of tweeters (especially ones that can emit efficiently in the range you want to annoy dogs) wouldn't exactly be inexpensive. also realize, while you don't "hear" above 20khz, you can feel it. and 20-40khz at the SPL you're looking for would have the side effect of giving you (and other humans) a terrible headache.

 

[tcmtech]

A 22 caliber bullet to a non vital area works pretty well too!

 

[unclejed613]

OP is in TN.... that might work.... i used to use a paintball gun myself. that way the owner knew when Rover had been a bad dog......

 

[gary350]

400 watts worth of amplifier wouldn't be difficult, but 400 watts worth of tweeters (especially ones that can emit efficiently in the range you want to annoy dogs) wouldn't exactly be inexpensive. also realize, while you don't "hear" above 20khz, you can feel it. and 20-40khz at the SPL you're looking for would have the side effect of giving you (and other humans) a terrible headache.

What is SPL?

If 400 watts is painful than maybe the dogs will run away. GOOD. At 2am everyone will be asleep in the house so it won't both us or anyone else. Motion detector will only stay on about 1 minutes.

As much as I would like to I can not do anything dangerious. You never know who is sneeking around in the dark at 2am. If I catch a thief, child molester or rapist in a trap instead of a dog it would be me that gets in trouble not the thief. What kind of screwed up justice is that. Sentence the child molester to 20 years in the low voltage electric chair.

I never see the dogs, I can not shoot them in the dark anyway, can't shoot a gun in the city limits, plus I don't own a gun anymore. Sold them all 25 years ago. Can't shoot guns anymore not even on your own property someone will call the police they don't want you shooting in their direction and they don't want to hear Boom, Boom, Boom, Boom, Boom, Boom, Boom, Boom, Boom, Boom, Boom, all day.

 

[audioguru]

Who says people cannot hear above 17kHz? Old people cannot hear above 17kHz but most young people can. Your idea will wake every young person in your neighbourhood. Their parents will call the cops on you for disturbing the peace.
I agree that 400W worth of tweeters will be VERY expensive and they will probably burn out anyway.

 

[tcmtech]

As much as I would like to I can not do anything dangerous. You never know who is sneaking around in the dark at 2am. If I catch a thief, child molester or rapist in a trap instead of a dog it would be me that gets in trouble not the thief.

What 3rd world slum do you live in?

Get a pellet gun pistol and load it up with little rock salt pellets. Quiet, hurts like hell, hard to trace, and really fun all in one!

The other option is to identify who's dog leaves you the yard mines and simply go around and return them to their owners the next night or better yet save them up for a while, soaking in water, then give them a big present in their front walkway!


For ultra sonic purposes piezo tweeters would probably be the most effective and efficient plus rather cheap as well. They could be driven off a simple HF power oscillator circuit/ step up transformer combo unit to get the power levels up high enough with a minimum of parts involved.

 

[gary350]

How about you come to my house and set up all night waiting for the dogs, maybe the dog will come before you fall asleep. Maybe the dogs won't come until tomorrow night. You can not shoot a dog in the dark if you can not see it. You also have to own a gun too so bring one with you. Now do you see why I want to use a motion detector.

I have a pickup truck load of speakers. For the past 30 years I have taken speakers out of every thing I threw away, old TVs, old stereo systems, old speaker cabnets, old radios, toys that make noise, anything that had a speaker in it I saved it. It will probably be an all day job to connect 200 speakers in the correct series/parallel or parallel/series connection to equal the correct ohms for the amp.

When I was in college electronic class we tested everyone in the class with a signal generator to see what frequency they could hear. No one could hear above 17KHz. With the signal generator I can set it to 20KHz or 22KHz or what ever it takes so it does not bother anyone. Then when the motion detector set it off at 2 or 3 am it won't bother anyone except the dogs.

I would be nice to buy some tweeters that can produce 150db at 200 watts but that costs money.

 

[jpanhalt]

I'm with tcmtech. When I lived in a Baltimore row house (1960's) , my room mate and I used a similar non-lethal method to control barking dogs. Clearly, the dogs were smarter than their owners. In one memorable case, the dog wouldn't even go out the back door. The owner was completely frustrated. We got our revenge without touching her.

John.

 

[audioguru]

Ordinary speakers do not produce 20kHz. In your school's hearing test you tested the speaker, not the hearing.

If you don't live in a ghetto where slobs let their dogs roam free at night then maybe you are mistaking the dog droppings for coyote or bear droppings.

 

[duffy]

I made a 50 W version of this when I was a kid, used a piezo horn tweeter mounted in place of the light in a lantern, 555, power transistor, and a step-up transformer to drive the tweeter. Looked great, ear-piercing when I cranked it down to 17 khz, but all it did to dogs was make them angrier.