hi folks, do you think this can be modified to emit super hi khz above 15khz? and what will it take?
my aim to emit frequencies inaudible to man but audible to animals
regards
gabriel
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Usually those are resonant only at one frequency, so you could make it emit other frequencies, but at a significantly reduced output level.
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Hi Gabriel
I’m not sure what you are looking for, but I found these to be very effective.
Ultrasonic transducers could have multiple resonant frequencies (although not all of them will necessarily be resonant in the longitudinal direction which is what you want for maximum acoustic energy). You can find the resonant frequencies (at least at low power) by driving it with a signal generator and monitoring the voltage and current while doing a frequency sweep. If you have a decent oscilloscope that can multiply the two measurements that can help as it will display power directly. You are looking for the frequencies where the power peaks. Since the resonance you are looking for is a mechanical resonance, you can tune it. The way we used to tune the transducers I worked with was to adjust the compression (We used toroidal shaped piezo elements with a rear mass on one end and a feed horn on the other with a bolt through the center holding it all together. You can increase the resonant frequency by increasing the compression i.e. making the bolt tighter)
tx @Solarphile , i have to smile at the ‘newspeak’ [ala george orwell ‘1984’] of deterrent which now resorts under the pc term ‘pet training’ for indeed what was once acceptable disciplining of children has now become ‘guidance’ and many a just plain naughty and belligerent child is the victim of the latter-day pc adhd, a victim and hence has to receive medical attention costing thousands if not ‘government assistance’.
but lest i drift into another thread - in the weeds i presume - thanks again and yes, indeed, the purpose of modifying the ‘sound bomb’ is indeed to ‘train pets’, since training their owners is not an option.
for the more sensitive and pc reader i can state that attracting swifts and swallows in order to occupy and breed in little boxes is one of my aims.
the ‘dazer’ though is a hand held unit whereas i am looking for a unit which will be fixed with a 12 or 220 volt supply and which i can switch on and off via wifi - the latter being the easy part through a sonof. obviously something like that can be purchased but being allergic to exploitation i’d rather purchase readily available parts and tinker with them.
regards
Me too! I had such a device, because I lived in an estate with small houses and small/no gardens. I had one of the houses WITH a small garden, which meant my lawn was the neighbourhood dog latrine.
I installed one of those devices, and it worked perfectly. The reason I know it works, is because all the dogs moved to the upper corner of the lawn, where the PIR detector could not see them. Since that was out of the way of foot-traffic, it was an acceptable outcome.
The device also kept the neighbourhood kids away to some extent. Teenagers can hear it… 
Anything to keep young adults away from home? 
Which brings me to another thing I forgot to mention. Just because you can’t hear a very load sound, doesn’t mean it won’t cause hearing loss. The device linked in the original post supposedly puts out 118db, which is enough to cause hearing loss. If you did manage to increase the frequency to just above the audible range, it would still be a bad idea to spend a lot of time near it while it’s working.
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tx @stanley - in my case it will not be aimed at myself and only used in short bursts, like yap yap - i’m aware of the dangers of ‘being assaulted by noise’ - even inaudible frequencies from my microwave and mobile 
I assume you’re joking, at least a bit, but those ‘frequencies’ from your microwave and mobile are electromagnetic, while the sound from that pet training device is a pressure wave, so they have very different effects.
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it was tongue in cheek… yet both are energy 
Did you have the Dazer (which looks like a button) and modified it to work off PIR?
Or something else altogether?
It was a complete product sold for the purpose of chasing off animals.
interesting, it states a frequency of 23khz - at the volume of a low powered unit like that no physical harm can be done. if provided in short bursts in response to pir activation it will provide a ‘pavlov’ stimulation deterring [irritating] whatsoever can ‘hear’ that frequency … most probably fish as well, i.e. training the animal to avoid that space. if the frequency was kept the same over a long period the target will get used to it and it will loose its effectiveness. in effect the pc way of referring to a unit like that would b a training tool hehehe. as man was given dominion over the animals in gen 1:26 he can certainly use stuff like this to responsibly control his surroundings - a right thus!
This is the device! This exact one in the picture. Bought it in 2004. It works perfectly, but I could actually hear it (probably the lower frequency parts), and the kids in the street reported that it hurt their ears. So definitely don’t use this where your kids or grand kids are around.
It does have an easy on/off button though for those occasions.
There are free phone apps that do this. Fun to play with kids to see who can hear the highest frequency. Kids can hear long after I can’t.
Before you spend money, try this app on your intended victim. Dogs can definitely hear the frequency.
I have tried it on at least six or more dogs. The first time you turn it on, they look at you quizzically and then, with great speed, they go back to sleep.
It does not make them stop barking or run away or even stop snoring.
… the irritation/pain/deterrent ‘quality’ depends on the power and frequency - is that not true in all cases? - and a mobile phone will have very little power although the frequency might be ok - sound, it is used as weapon as well, pretty clued up info here LRAD vs "Volunteers" - Field Test - YouTube
I prefer this one:
Probably not at the mobile phone level. The above green device was uncomfortable even to MY ears (which at the time was around 30 years old, along with the rest of me).