Siren Project

Audioguru

Joined Dec 20, 2007
11,249
The 560R and 220nF are supposed to be a low pass filter at 1.3KHz.
No.
It has the fairly low 560 ohms resistor in series with the same output impedance of the PIC so the cutoff frequency is about 649Hz.

The 100R and 20R are a voltage divider to take the 5V peak to peak signal down to 1V for my stereo line in socket
No.
The 100 plus 20 ohm resistors load down the output of the filter so it doesn't filter anymore. they also load down the 560 ohm resistor and also load down the output from the PIC. The output of the 20 ohm resistor will be about 0.069V peak which is too low for a line output.

Your problem is that your resistor values are so low that they need the very low output impedance of an opamp to drive them. But many opamps also cannot drive resistor values so low.
The Pic should drive a load of at least 5k ohms, not just 680 ohms.
The filter should feed a load of at least 10k, not just 120 ohms.
 

Markd77

Joined Sep 7, 2009
2,806
Nice, thanks.
It's got a bit louder with changed values of 4.7K and 22nF for the filter and 6K8 and 1K8 for the divider. It also sounds a bit harsher so the filter frequency must have gone up as you say.
The PIC should be able to source and sink 20mA so the issue may have been more with the voltage divider, but it will be happier with less current.
Final values will probably change because the police probably won't want to carry my amp around with them and I don't want to part with it anyway.
 

retched

Joined Dec 5, 2009
5,208
Final values will probably change because the police probably won't want to carry my amp around with them and I don't want to part with it anyway.
I dunno, you can probably get them to pay a pretty penny for it. ;)
 

Thread Starter

R!f@@

Joined Apr 2, 2009
9,750
Nice Piece of software Sgt. Thanks.
I need a wave file to convert it to 1 bit.
Mark cud hard code it since he mentioned something about it
It will come in handy if I could get a recording from the current siren they have.

Things a getting a lot easier when I have you guys around.
Don't like to even think about where wud I be if you all are not there.

I hope to meet Staff Sgt with contractor of Siren Project today at around 900 Hrs or later.

By the way Mark, I do not think they would want a heavy duty amp to carry around a two wheeler. :D

and retched.
How's our little thing ;) going on. I have a few plans to light the inside.
I will send a clip soon on the lighting.

I need to contact BMorse abt the lighting.

So Many things, and so little time.

My sister's due date is today and still she show's no signs of a contraction.

And today the lean concrete is going to be layed on my home foundation.
Just came home to have breakfast. Going to take off now.

See you guys tonight.

Thanks a lot to all of you.
 

Thread Starter

R!f@@

Joined Apr 2, 2009
9,750
I met them yesterday.
And here are some things that I found about from both parties.

* The police doesn't know what the siren they are using now. So they cannot recommend any thing from UK to US sirens. They want it as loud as possible but they have no clue what is a decibel level or power rating. Typical.

* The cycle company decided to use the 3.5A battery that is now currently used in the cycles. Previously at first when I bought the same model it had a 7A Lead acid, which I switched to 12A SLA and did not have a charging problem. Provided that I drive it. :D

* The techs at the cycle dealers thought of putting another battery since it has plenty of space underneath the seat. And was preparing to switch the battery through a relay. They would switch the battery thru switches mounted at the handle. But have no Idea when they should be switched and would the driver will have any idea on when to switch them.

* another point what they never thought of was in order to make the cycle cheap the new ones have low dynamo rating and charger circuit. I asked them how well they were informed on the capacity of the dynamo...the tech went :confused::confused:. Go figure.

* Even though they have planed on putting a new battery (extra) and installing a built in bull horn siren, they had no idea on how long will it last or their method will work on charging battery without hassle form the buyer.

* They want it done in 3 months in addition to the flashers.

Given the schedule I have, a miracle has to happen :eek:

So here is my opinion which I explained to them quite clearly

The police siren is something unique to each country, it did not need to be a UK or US based one, what we need is a siren that will make a bystander **** in his pants. not literally though.
Even though they are Police they have no idea on how the Maldivian young crowd will respond to them, these youngsters have far more powerful horns and sirens. If the police installed a siren that is easily available the crowd will get them just to annoy the cops. They have no respect to the police.

Did you know that these guys have built in 500W car amps into the cycle extra space and mount speakers on the sides, they play loud music while they drive. They really annoying but quite funny. Even though their battry goes flat with in minutes they do not care, cause they have garages and they customize the cycles to show off.

So, If it was for me, the cops should have something that is hard to replicate and something which is not available in open market, cause I can guarantee that these young dingbats will try to copy it, they would even steal the cycle to take out the circuitry.

I explained then the typical power rating of a bull horn and explained them ways to have it mounted out of sight yet produce deafening siren.

I showed them how I could make the siren circuitry fool proof too.

And also online battery voltage monitoring circuitry to keep an additional 10A battery topped up. Automatic switching between batteries to keep them both fully charged.

But I said I cannot finalize a prototype in 3 months period. I can make them the flasher but to built a loud reliable siren they have to give me type and invest in it :D.

Guess what?
They agreed if they win the bid. the bid will be due soon, this time their were 3 more parties, I donno where the heck they sprung from.
OK..we have Honda and Yamaha ...cool well known brands here.
Being here as long as I can remember.
but I really donno what the other two are.
And how they can get the timing of the flasher that I built which by the way is already in use.

Any one can make a flasher, but the way you guys helped me to make it is very different. Ofcourse their are programmers here but I am sure they cannot customize it as much as I did and install 1000 Leds in the cycle side lights. There is just one who can do what I do, and he is a good friend of mine, some one I can really trust, as he lives and works same way as I does. And I know he won't touch anything that I am involved as from time to time I help him to repair the SMPS units of the submarine here.
Yes..he is the a very good tech running a fire alarm company totally customizing the items plus he is the tech taking care of the submarine where tourists go for tours. I am the one repairing SMPS as he is not familiar with them.
See the relation I have. These are the types we need here but are only few. He would do anything for me and I would do the same. He is very good at what he does but still he asks me, but I cannot sometimes do what he does cause I am not a programmer.

Well so much for that.
Mark I will keep in touch and I too have some file that I would like u to see. With the help from a wonderful member Sgt. I too managed to get a ASM file from a wave file.

I will check mark's ideas in due time as I have not been able to get time on my hand.

Later
 

Markd77

Joined Sep 7, 2009
2,806
ASM from a wave file, sounds useful.
I had a bit of a play for my amusement and came up with a fairly interesting sound. I think it would be more penetrating than a simple note.
I also found some code for a white noise (static) generator. I've heard them in the UK alternating with the siren. Might have been on a fire truck.

http://www.marksphotos.info/siren/MOV00269.3GP
 

Thread Starter

R!f@@

Joined Apr 2, 2009
9,750
Hi there. No news yet.

Just something I have been thinking that would make a great yet effective addition to the new flashers.

I was thinking of a way to sync the flash timings.
At most of the time there would be one or two cycles on siren flash.
But if a motorcade is there then all will be cycles will be active. Won't it be pretty if all the cycle's were in sync, it will make one hell of flash.

To do this, the way I think would need one transmitter to transmit the timing pulses.
The slave will just follow it.
The slave program must be modified to look for sync, if there is then sync it, if not, go on normally.

Of course slave should have a receiver circuit. This is where I will need help.

What I suggest to go for 2.4Ghz transmitter. I really donno how I should go abt it and what I will need. So I open this for discussion since I think I have time.

But bear in mind that a motorcade like this will probably have a jeep with cellular jammers active. Since all of the cell in the area loose network when the black jeep with antennas from all sides is in the vicinity.

Question is what it would do to a 2.4Ghz pulses that I will need to transmit to close range
 

Potato Pudding

Joined Jun 11, 2010
688
Broadcast the siren across the Public Broadcast FM band. Everyones radios will be tuned to Siren Radio. (This is probably illegal so they might have to arrest themselves.)

:)
Call it a feature to prevent people with loud radios from drowning out the Sirens.

If the bikes use transceivers then their PLLs should be able sync up their transmitters almost automatically. With some kind of feed back to the sirens syncing up their sirens should be nearly as easy.

The bleats of the sirens are used to sync the flashers. Flashers flash and sirens scream at the same times, once all the bikes sirens are in tune.

In theory you don't need to use radio at all. You should be able to just include a microphone and use an audio frequency PLL circuit.
 

SgtWookie

Joined Jul 17, 2007
22,221
Use the broadcast time signal to synchronize an internal clock in the uC's. Either that, or have an internal (accurate) timekeeping routine in the uC (see Roman Black's site) and only allow it to be set at the police station.

If you rely on a radio transmitter and multiple receivers, your mischief-making Maldavian miscreants will soon figure out how to interfere with it.

As far as the civilians with annoyingly loud systems - they should pass a noise abatement ordinance to prohibit such activities. Someone's blasting a stereo loud enough that it's an annoyance, their equipment should get confiscated and they should be fined. That kind of stuff isn't funny; it's downright stupid, annoying, and can certainly cause loss of hearing.
 

Kermit2

Joined Feb 5, 2010
4,162
I am still puzzled by the need to run this on 4 A batteries.

Don't police cars in your country have 12 volt batteries in them?
 

Audioguru

Joined Dec 20, 2007
11,249
Do the police in your country (which country?) drag the bad guys along the road behind their little bikes?
The police in Canada use powerful sports cars and SUVs that have plenty of room inside for the bad guys to go to jail. Sometimes they use a huge bus.
 

Kermit2

Joined Feb 5, 2010
4,162
Do the police in your country (which country?) drag the bad guys along the road behind their little bikes?
The police in Canada use powerful sports cars and SUVs that have plenty of room inside for the bad guys to go to jail. Sometimes they use a huge bus.

Perhaps they slap a tire boot on them so they can't go anywhere till the paddy wagon can come around and tow them off.

:)
 

Thread Starter

R!f@@

Joined Apr 2, 2009
9,750
Do the police in your country (which country?) drag the bad guys along the road behind their little bikes?
The police in Canada use powerful sports cars and SUVs that have plenty of room inside for the bad guys to go to jail. Sometimes they use a huge bus.
Here in Maldives, Police use buses or vans..no cars but they do have jeeps.
There cycs are for emergency cases and chasing runaways
 

Audioguru

Joined Dec 20, 2007
11,249
Oh. The Republic of Maldives near Sri Lanka and India.
Its population is about as small as my neighbourhood. It does not allow any religion except Islam. It has a very low average height above sea level (1.5m) so it will be sunk soon by the rising oceans.
 
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