We recently had the misfortune to have an 'inconsiderate' young couple to move into the cottage next door. The guy uses 4 letter words frequently and loudly. The girl has a loud voice and raucus laugh. A neighbour 3 houses away can hear every word of their conversations/arguments/phone calls but whats worse is that on warm summer evenings this goes on in their back garden. Yes I asked nicely for them to keep the noise down but was told p*ss off and had the girl saying 'bring it on' etc (believe it or not she teaches kids art!!!). So now the time has come for 'retribution' or should this be 're-training'?!
What I want to build is a HF audio generator that will cover around 14k to 20k. I want to amplify this to a lot of watts and put it into a powerful tweeter or HF horn. Here's the clever bit - I only want it to fire off when it detects noise above a certain level in the speech spectrum, so when these people or their friends are noisy they get blasted with a shot of HF noise back. When they stop to 'listen' to what the noise is and where its coming from - nothing! Hopefully they will find it so unpleasant they will go indoors. I already tried playing frequencies around 15k to 17k to my kids from the laptop (minute speakers) and they say its quite loud and annoying (at 2m distance). I sat in the garden and played the sound clips and got the comment between the girl and the guy next door "Is that a phone ringing?". So - how bad will this be for them at xx watts at midnight or 1am when they are having noisy conversations in their garden?!
Now for the technical bit - a circuit for the sound generator - adjustable please for the most annoying frequency - should this be sine, square, sawtooth? Should it 'warble' or be a constant tone? Then I need an amp powerful enough to amplify it and make it unpleasant. I also need a circuit I can connect to a mic I can hide in the hedge that will 'trigger' the HF generator and amp. It needs to have an adjustable threshold and filter so it doesn't trigger with the HF sound (feedback). Finally I need some sort of high power rated HF tweeter but should I go for piezo or conventional? How does one drive a high impedance piezo compared with standard 8 ohm unit? Can one obtain directional tweeters that would direct the sound mainly in their direction? The people we are aiming at are region 25 yrs old whereas we are in our 50's and can't hear higher frequencies. Would there be any possibility of hearing damage if we can't actually hear the sounds?
I need to cover a distance of around 10 - 20m from our hedge boundary so how many watts at HF? Also at HF would our neighbours be able to pinpoint the source? I guess if it only comes on when they make a noise this would be difficult for them.
So circuits and suggestions please! And thanks in advance!
What I want to build is a HF audio generator that will cover around 14k to 20k. I want to amplify this to a lot of watts and put it into a powerful tweeter or HF horn. Here's the clever bit - I only want it to fire off when it detects noise above a certain level in the speech spectrum, so when these people or their friends are noisy they get blasted with a shot of HF noise back. When they stop to 'listen' to what the noise is and where its coming from - nothing! Hopefully they will find it so unpleasant they will go indoors. I already tried playing frequencies around 15k to 17k to my kids from the laptop (minute speakers) and they say its quite loud and annoying (at 2m distance). I sat in the garden and played the sound clips and got the comment between the girl and the guy next door "Is that a phone ringing?". So - how bad will this be for them at xx watts at midnight or 1am when they are having noisy conversations in their garden?!
Now for the technical bit - a circuit for the sound generator - adjustable please for the most annoying frequency - should this be sine, square, sawtooth? Should it 'warble' or be a constant tone? Then I need an amp powerful enough to amplify it and make it unpleasant. I also need a circuit I can connect to a mic I can hide in the hedge that will 'trigger' the HF generator and amp. It needs to have an adjustable threshold and filter so it doesn't trigger with the HF sound (feedback). Finally I need some sort of high power rated HF tweeter but should I go for piezo or conventional? How does one drive a high impedance piezo compared with standard 8 ohm unit? Can one obtain directional tweeters that would direct the sound mainly in their direction? The people we are aiming at are region 25 yrs old whereas we are in our 50's and can't hear higher frequencies. Would there be any possibility of hearing damage if we can't actually hear the sounds?
I need to cover a distance of around 10 - 20m from our hedge boundary so how many watts at HF? Also at HF would our neighbours be able to pinpoint the source? I guess if it only comes on when they make a noise this would be difficult for them.
So circuits and suggestions please! And thanks in advance!
