# Anyone Have A Diagram?



## Roger (May 17, 2003)

Some friends of our are having problems with teenage yobs congregating outside their premises at all hours causing some lack of sllep and distress.

They have read good reports of a device called "The Mosquito" whicch emits an ultrasonic noise which people under the age of about 18 find annoying and which causes them to move away.

Folks over the age of about 18 cannot hear it.

I am guessing that it works at about 18 to 20 Kilohertz.

I have the facilities to build such a device....does anyone have a circuity diagram?

Thanks

Roger


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## Regal325 (Aug 5, 2005)

Roger

If you are successful,

I would be more than happy to pay you to build one for me.

Ken


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## jasonm (Nov 22, 2003)

I thought that was a wind up?


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## Roger (May 17, 2003)

Jase,



> I thought that was a wind up?


No.... 12vDC I think









No..its available...Â£400 there is a website......supposedly endorsed by Avon & Somerset Police....mind you...they are bottom of the recently published league table....


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## jasonm (Nov 22, 2003)

I walked into that one...

Im still sceptical









I cant think of a physiological reason why/how it would?


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## Roger (May 17, 2003)

Jase,

The cat-scarer versions defineatly work...I have a commercial one...that runs at about 23Kilohertz, but humans need a lower frequency....they do seem to work...some users are reprting great success...

personally, I would prefer to use a 410, but that doesn,t seem acceptable any more


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## jasonm (Nov 22, 2003)

I get that a ultrasonic noise would do it but its the adolecent only aspect I cant get my head around...

Just play Cliff Richard a bit loud at em....


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## neil_s (May 29, 2006)

Hi,

I bought this thing to keep mice away. Its called a pest clear 2000. It has two settings , "Ultrasonic" for mice and rodents, and "Mosquito" for ...

Anyway neither me (36yrs) nor my 13 yr old son can hear it when it is on "Ultrasonic". However, when set to "Mosquito" I can't hear it but my son can and finds it really annoying.

Here is a circuit that gererates sine waves in a range of 16 to 22000 Hz

http://www.redcircuits.com/Page82.htm

Neil


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## mattjg01 (Jul 3, 2006)

Presumably after you reach a certain age the range of sounds that you can hear deteriorates. I'm surprised that it's such a precise cutoff at 18 I'd imagine it varies by person.

Roger if you do manage to rustle up the circuit diagram I'm sure you're gonna have a line of people waiting to get one from you.

Matt


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## marius (Mar 11, 2005)

I though anyone 18 and under were completely deaf! They never hear when I tell them anything, I thought the bassboxes in their cars had finally made them all deaf.


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## mach 0.0013137 (Jan 10, 2005)

How about this for a solution to the truancy problem in schools, have these things set up everywhere except the actual school so the little darlings would want to stay there for some peace and quite









It could also be used in the evenings to keep them off the streets


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## Roger (May 17, 2003)

neil_s

Thanks for the link...a good start...I quesstimate the cost of those bits at abot Â£4 plus the fabrication of a PCB...added to this you would need a high power audio amp, say 25 watts or so and a piezo tweeter capable of handling the 25 watts....certainly not Â£400 as per the commercial item...I am wondering if the tone needs to remain constant or does it need to modulate slightly....whichever is the more annoying.

Jase...

your hearing of higher frequencies dies off rapidly with age....at, say 20, many people cannot hear 18 kilohertz (not everyonel of course)...I cannot hear much above 12 kilohertz....so gawd knows how much Roy hears!























I will look further into it

Roger


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## mach 0.0013137 (Jan 10, 2005)

Roger said:


> so gawd knows how much Roy hears!


Mostly he just hears this constant ticking noise


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## marius (Mar 11, 2005)

Roger said:


> neil_s
> 
> Thanks for the link...a good start...I quesstimate the cost of those bits at abot Â£4 plus the fabrication of a PCB...added to this you would need a high power audio amp, say 25 watts or so and a piezo tweeter capable of handling the 25 watts....certainly not Â£400 as per the commercial item...I am wondering if the tone needs to remain constant or does it need to modulate slightly....whichever is the more annoying.
> 
> ...


I have a (quite old) book about human factors in engineering, which makes a blanket statement that "a child can hear 20000 Hz. At age 20, one can only hear up to 15000 Hz. Hearing loss is at a constant rate with advancing age, from 2% minimum to 3,5% per year, (based on pitch)." How accurate is this? I dont know, the same book says nobody can distinguish colours from the corner of the eye!


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## neil_s (May 29, 2006)

Roger said:


> Thanks for the link...a good start...I quesstimate the cost of those bits at abot Â£4 plus the fabrication of a PCB...added to this you would need a high power audio amp, say 25 watts or so and a piezo tweeter capable of handling the 25 watts....certainly not Â£400 as per the commercial item...I am wondering if the tone needs to remain constant or does it need to modulate slightly....whichever is the more annoying.


There is an easier way in terms of part count. The "Microchip PIC" programable IC.

They sell ones for about Â£4 that have analogue outputs but you have to program it.

Also you should be able to find some PC software that is a sound generator for a PC sound card. The sound card would have to support the high freq required though.

Or perhaps you prefer Linux;-)

http://www.baudline.com/index.html

test your hearing with this...http://www.dogstar.dantimax.dk/testwavs/sweeplin.zip

"This starts with one second of 20 Hz, followed by a fast "sync pulse" which might conceivably be useful for synchronizing a storage 'scope. Immediately thereafter, it sweeps linearly from 20 Hz. to 20 kHz. at a level of -3 dB (relative to 0 dB = 100% modulation). Total duration of the sweep is ten seconds." quoted from ...http://www.dogstar.dantimax.dk/testwavs/

neil


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## Stan (Aug 7, 2003)

Roger said:


> so gawd knows how much Roy hears!
> 
> 
> 
> ...


I worry about his eyesight and sanity after he's read all the demented e-mails he gets.


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## Roger (May 17, 2003)

> There is an easier way in terms of part count. The "Microchip PIC" programable IC.
> 
> They sell ones for about Â£4 that have analogue outputs but you have to program it.


true... we use Atmel PICs at work, so I have access to a programmer.


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## Mrcrowley (Apr 23, 2003)

neil_s said:


> Roger said:
> 
> 
> > Thanks for the link...a good start...I quesstimate the cost of those bits at abot Â£4 plus the fabrication of a PCB...added to this you would need a high power audio amp, say 25 watts or so and a piezo tweeter capable of handling the 25 watts....certainly not Â£400 as per the commercial item...I am wondering if the tone needs to remain constant or does it need to modulate slightly....whichever is the more annoying.
> ...


I tried Dogstar. Couldn't hear anything past 5 seconds. What does this mean?


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