Extremely Loud Piezo Buzzer (multifrequency)

[GTechno13]

I'm building a security system for my car and would like a (piezo) speaker loud enough for the alarm under the hood. I would like it to work just like the little ones where you can feed it whatever frequency square wave (50% duty) and it produces that tone. It just needs to be really loud! On mouser, I'm having a hard time finding anything like this. All the loud ones are a single frequency or a siren. Maybe I'm not looking in the right places.

I assume this needs to be piezo based and it will need to run at 12VDC. Oh and be $20 or less but more expensive examples are welcome.

Thanks!

 

[Sceadwian]

Why? Use the cars horn, it's easy to tap that, and it's free cause it's already built into the car.

 

[GTechno13]

Why? Use the cars horn, it's easy to tap that, and it's free cause it's already built into the car.

I want to have more control, customization, options, and just to plane sound more fancy. When I lock my car now it honks. A "chirp chirp" would be much more likely to deter a would-be thief if they were casing a parking lot I just pulled in. This security system is running on a micro controller with a host of different sensors and will be controlled from my cell phone via GSM so I have unlimited range. All that and then just the horn to communicate to the outside world? I want to program in a wolf whistle too.

 

[Grossel]

Hi.

A simple multi tone generator could consist of t.ex:
Two adjustable multivibrators, and a XOR gate. The output should be a sort of mix between those frequensis.

 

[Sceadwian]

As far as the transducer goes, do you have any friends that work at car shops or what not? Make friends with someone that does car alarm installations and see if you can get them to let you take a look at the transducers that they use, they're loud as hell and make all the buzzs whirs chirps and tones you can throw at them.

 

[GTechno13]

Most of these car alarms seem to have the sound effects built in. Apply 12v and they go through a whole gamet of annoying sounds. I just found this interesting thing on ebay. It says it's an "**broken link removed**". It looks like a normal speaker but says 12v. I suppose I could drive it my square wave at 12V and it would work? I don't know much about regular music speakers and how they are driven. (volts/amps and such) Is there something special about this little guy that differentiates it from a normal speaker? Would it be as loud as a piezo? At $10 it might be worth a shot.

 

[Sceadwian]

It'll sound like a square wave though. Piezos naturally filter out a lot of the harmonics, a speaker will not so it's going to sound quiet different than the clean tone you're probably looking for, you'd need to feed it a real sine wave for clean sound. I'm a little iffy on the specs given for that horn as well. It says it's rated for 12 volts and 100 watts, but that means the coil resistance calculates out to 1.44 ohm which sounds low, most car speakers are 4ohm which means the REAL power output of that speaker would only be 36 watts absolute maximum. The 100watts listed is probablhy maximum peak power that it is capable of taking, which you'll never hit. For the price though it seems like a good bet to try you'll never get bass out of it but it should do midrange and highs just fine.

 

[SNIPE]

you could use a 150dB electric horn and a relay

 

[cr0sh]

A "chirp chirp" would be much more likely to deter a would-be thief if they were casing a parking lot I just pulled in.

That, or it might say to the would-be thief "Hmm - he has something to steal...".

I am not even sure people pay attention to when car alarms go off anymore, and even if they did, do you think they would a) call 911, OMG - he's stealin'!, or b) NMP, let's keep walkin'! In this day and age, people tend to ignore anything and everything up to rape and murder, and sometimes even that.

You really want to protect what you have? Don't show it off. Drive a beater. Roll up your windows and lock your doors. Have good insurance.