Quiet Noise Secret Weapon. Advice please.

Thread Starter


Joined Jan 8, 2015
I'm having a problem with people hanging out in the vicinity of my home front entry stoop. Looking to cause them subtle discomfort and thus to avoid loitering. Came up with a 200 W amp setup for a 22 K Hz. tone generator. The sound should be very disturbing without the source being evident, hopefully then people will move on quickly. Although I'd like to shoot, or release the hounds, I must be practical and legal.

I'm having problems identifying compatible components and don't want to screw it up. I have four horn tweeters, each rated at 100 watts, wired in series / parallel, to give me 8 ohms impedance. The amp is a Sanyo chipset, rated at 200 watts, linear, single channel (STK4050XI) into 8 ohms, which requires between 66 and 90 VDC (details attached). I've purchased a 300W toroid audio transformer rated as 110/220 primary, w/ 50-0-50 and 12-0-12 secondary outputs. So, I should be able to get outputs for my amp and for the signal generator. I'm very concerned about the power supply filter stage output voltage being on the money here. I'm using a dual rail six 10,000 uf capacitor / and 4 switching diode power supply assembly, rated at 80 volts (schematic attached).
The tone / signal generator is a simple 5 vdc module with which I can finely adjust my output frequency with a trimmer pot. I'm wondering how clean the power supply needs to be on this module. My plan was just hooking up a simple bridge rectifier on one of the 12 v secondary legs of the power transformer, with maybe a small capacitor (value suggestions would be appreciated) across the output feed.
I trust that I can simply hook up the 50 volt CT leads to the rail inputs of my filter and get the correct voltage output, at roughly 66 volts DC.

Are there any items which I'm improperly addressing, particularly with the power supply portion of this setup?
I've tried to be clear in my presentation and I'm attaching a couple of schematics, perhaps TMI. I'm hoping that I'm not making some newbie mistake in protocol. If so, your tolerance please.
Your advice, of any sort, is truly appreciated.



Joined Oct 2, 2009
You could bathe me in 22kHz sound all day long, and I wouldn't even know it was there. You will drive all the dogs that live on your street knuts, but people wont even notice...


Joined Sep 17, 2013
How about a stink generator? A few watts should be enough to heat some noxious substance (any chemists out there who can advise?) to give off fumes, and a small PC fan could distribute them.


Joined Nov 30, 2010
Another idea: 200 watts of Metal Halide or High Pressure Sodium light in a couple of hundred square feet would make most people uncomfortable. (Human rats don't like bright lights.)


Joined Nov 30, 2010
Post #1, line #1: "home front entry stoop". That might be 100 square feet, 400 square feet...need to know, please.

Thread Starter


Joined Jan 8, 2015
Hello All:
Thanks for taking an interest here with my project. To clarify a few points, The materials have been for the most part already purchased or may have been already on hand. The area I'm trying to cover is open, grass lawn with a small gravel road used by adjacent property owners and guests, about 100' from my door. Problem is that they tend to gather with their dogs at my frontage and chat. It drives my dogs crazy, and there's the rub, as it disturbs our quiet household.
I want to do this without anyone knowing that it's going on. I've seen some studies about sound frequencies just above human hearing negatively affecting the subject, making them uncomfortable. So thus my action. Would've loved to hit them with the sprinklers, but it just can't be done.

My major concern is transformer output voltage and power supply output voltage being correct. I have learned all of my electronics by reading and or doing, and making the mistakes that teach us all so well. I've not worked previously with center tapped transformers or split power supplies, and this was the most expensive portion of the project, so I don't want to screw it up.

Thanks for your help and commentary.


Joined Sep 9, 2010
The TV in my living room drives my kids crazy with a high-pitched hiss. The older adults can't hear it at all and there's no way it would drive them away. Of course the volume is minimal, but it's enough to make the kids wince.

So I'm very skeptical that there is a frequency where this will work reliably for people with a range of hearing acuity. Younger people will know what's going on and the older people won't care.

But, experiment and prove me wrong.

I'd supply the tone generator with a nice regulated supply using a 7805. Actually, until I had proof-of-concept, I'd just use an old iPod or smartphone as my tone generator. There are free apps that enable this. Hitting 22kHz might be dicey, but 20kHz should be in range.

I'm confused about your other questions: Are you using automotive audio equipment? I don't understand why you wouldn't just use a commercial audio amplifier which you can buy very inexpensively. If proof-of-concept pans out and you need to modify things, maybe then build something DIY.

And, have you considered just posting a sign, asking politely? Maybe one like this.


Joined Nov 30, 2010
and yet another opinion:
Dogs bark because they believe they should.
Who taught them to bark?
You did.
Why did you teach your dogs to bark at familiar people standing in a public right of way?
Don't answer that, just teach the dogs new rules or teach everybody else in the world that you own the road and they aren't allowed anywhere near there.


Joined Nov 30, 2010
Don't pretend I don't like dogs. I do. I raised show dogs for 8 years. I understand dogs. Some people even say I can speak "dog". What I don't like is people complaining that their dogs do exactly what they were taught to do. Take responsibility for your own choices.


Joined Nov 4, 2013
So you figure that sending out a ear ripping 22 KHz tone will not drive the dogs off the deep end before the humans? o_O

You might want to think this through a bit more given the audience you are targeting and the critters who will obviously be in the vicinity.

If the barking dogs are the concern this will definitely not help anything. :(


Joined Oct 15, 2009
Sounds like someone needs a flaming bag of poo-poo on their doorstep. :)

I'd be pissed (and probably call a lawyer) to find out the grumpy old man on my street was trying to cause nausea/pain/discomfort,etc.. on me without my knowledge from some DIY device that hes shooting at me.


Joined Aug 1, 2013
Don't confuse inaudible with safe. High frequency ultrasonics, especially just-barely-ultrasonics, are just as dangerous as The Who. 200 W ?!?!? Try 5 or 10 W to start and see if it works.



Joined Aug 21, 2008
It depends on the age of those congregating. Some young people can hear 20 kHz without a problem, but more generally, 10 to 12 kHz would do the job. Also, I read that for people in their 20's and under, playing Frank Sinatra generally gets young people to avoid the area. True!


Joined Nov 23, 2012
I just completed a brake job on an old Camry. Took it for a test drive and 100 yard from my driveway I applied the brakes - I was next to a woman walking her dog. As soon as I applied the brakes, the dog jumped and twisted and yelped like it was in pain. The brakes were silent to me and nothing else was there to scare the dog. I couldn't imagine how the dogs will jump at 200db!