Car alarm sirens - does the siren make the diff sounds, or the CPU?

[MichaelD]

In more detail:

A car alarm siren: I know it's a speaker, but does the speaker itself have a chip that makes the diff sounds, or does the CPU make the diff sounds and sends them thru the wire (like a home stereo--->speakers)?

Inquiring minds want to know. I 'm going to build the biggest, baddest car alarm this side of insane. You'll go deaf from 100 feet away.

 

[bmacd]

bump
i wanna know too.

-=bmacd=-

p.s. i would have guessed that the it's the physical siren making the noise, otherwise, it'd be called a speaker.

 

[MichaelD]

Originally posted by: bmacd
bump
i wanna know too.

-=bmacd=-

p.s. i would have guessed that the it's the physical siren making the noise, otherwise, it'd be called a speaker.

I am thinking along these lines too...I'd like to know for sure, though.

 

[sohcrates]

the "siren" is basically a speaker in a tunnel (to amplify the speaker) i.e. a "horn speaker"

the speaker "diaphram" is vibrating at different frequencies to produces different sounds (or "warbles" in the case of car alarms)

the "cpu" of the alarm is basically sending certain pulses to an amplifier which drives the horn speaker

so basically, yes, it's like a home stereo...think of hooking a pair of klipsch horn speakers up to a stereo, and playing a cd with test tones...same concept..except here the "cpu" is the cd (i.e. different sounds are hard coded most likely in some form of non-volatile onboard memory)

 

[MichaelD]

OK, thank you Socrates. I wonder how many sirens I can hook up to the alarm brain? Guess I'd have to check the impedance of the sirens and what impedance the output of the brain is rated at.....

 

[sohcrates]

[Guess I'd have to check the impedance of the sirens and what impedance the output of the brain is rated at.....

yessir...it's just like figuring out how many speakers you can hook up in parallel or series or whatever.

horns will have an impedance rating just like any other speaker...only difference is that they're VERY efficient, which most speakers are not (i.e. very little power makes a VERY loud sound....)