Sound Generator

Hello all,

I would like to built a sound generator for my Room Monitoring system.Can someone suggest me any electronic design as I would not like to use HT2810 or HT2812 sound generator integrated circuit, being quite expensive to purchase.
Does anyone know if using Microphone can be another alternative? Thanks in advance.

What kind of sound do you want to generate? What is the purpose?

This is from the "HT2812 datasheet":http://html.alldatasheet.com/html-pdf/114860/HOLTEK/HT2812/215/1/HT2812.html in place of the key connect it to your microcontroller.

As I am designing a Room Monitoring System using PIR sensor , I would like to generate some sound so that I can alert others that someone is in the room.

So you just want to make a indicator sound? If so, you don't need anything special.

You can use one of those buzzers that makes a sound by itself when you apply power, or a passive transducer driven from a microcontroller pin via a transistor. There are lots of other ways too, depending on how loud, small, low power, etc, it needs to be.

Your circuit surely has an output right? Simply use a transistor or a 555timer as an astable to generate a variable frequency output that can sound a buzzer or any other beeper or sounding device, use them at the output of your main circuit.

Check out the "Buzzers" category under "Audio Products" on the Digi-Key Website (see attached picture). Buzzer is a little misleading, they don't all just buzz, one of the parametric columns of the search lets you filter by type of sound they make.

Try to parametrically filter down to a suitable option via your available voltages and how much current you can source from them. Like Olin mentioned, you will likely have to drive it through a transistor (which of course conveniently acts as a switch too) for the needed drive current. If you find one with an internal drive/transducer that can run off a DC voltage rail you have available then you are pretty much all set, just connect the wires and your switch correctly.

If you want something cool and fancy though you could check out this "PUI Recordable Indicator":http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=US&KeyWords=recordable+indicator&x=0&y=0 that lets you use a free software tool from the manufacturer to put any short MP3 you want on the device.

One of the engineers at Digi-Key put the nuclear attack warning siren sound on one just for fun when he was launching a model rocket. I bet they get a lot of customized doorbell sound do it yourself types that like them too.