Cheap mini microphones

[Sceadwian]

I'm thinking about a small audio/visual project, of extreme simplicity but very scaleable. Basically all I want to do is use a small cheap 8 pin micro controller, microphone, LED, and coin cell to create tiny little sound sensative LED, thing is the package needs to be small, I don't want them larger than the size of a quarter, preferably a dime. Price is also a problem as I'd like to build perhaps 100 of them at least that's my goal. I'll start off with one which is easy and cheap enough and see what happens when I scale up to 10. Price is the real problem though, I can't seem to find any compact microphones that would fit the bill and still be cheap enough to eventually buy 100 of. I'm looking for a normal audio frequency responce of 30hz to 20khz and a price as close to a dollar as possible, not finding anything even close to that price range though. Suggestions would appreciated.

 

[dknguyen]

I thought most earphones don't even cover 30Hz to 20kHz. Isn't it usually 20Hz-15kHz or something like that? Microphones are expensive....I don't know of any. Any idea what kind of microphone you want? Piezo or electret?

Maybe look at surplus? These surplus "spy mikes" might interest you
2/$1 - https://www.goldmine-elec-products.com/prodinfo.asp?number=G1841A
100/$45 - https://www.goldmine-elec-products.com/prodinfo.asp?number=G1841

But perhaps these 20Hz-16kHz SMD Mics are more to your liking (more info and cheaper too):
2/$1 - https://www.goldmine-elec-products.com/prodinfo.asp?number=G1820
100/$38 https://www.goldmine-elec-products.com/prodinfo.asp?number=G1820A

Why do you need such a wide bandwidth anyways? I would think just enough bandwidth for recognizable sounds is good enough.

 

[audioguru]

You will need an opamp for a microphone preamp.
A little 3V lithium battery won't last long powering a flickering red LED. Two wouldn't last long powering a flickering blue or white LED.

What will the microcontroller do?

My Sound Level Indicator project blinds everybody who makes a noise in my house. It can hear and indicate a pin dropped that is pretty far away, or very loud sounds.

 

[Sceadwian]

Don't a lot of electret condensors have a built in jfet pre amplifier? Those look about what I was looking for, price seems about right too thanks.

 

[Nigel Goodwin]

Don't a lot of electret condensors have a built in jfet pre amplifier?

They all do, it's required to match the electret element.

 

[ericgibbs]

hi sceadwian,
Have a look at the 'SiSonic' silicon microphones.they are about 6mm sqr,
cost in UK 10pence each. They are surface mount 'die' mic's 100hz thru 10khz. They are also useful if you ever need to construction an acoustic
array. Let me know if you have problems locating the device.

Regards
EricG

 

[Nigel Goodwin]

You might try looking at Velleman kits (and steal the circuit, which should be on their website) - they do a small kit with an electret mike, that feeds a string of five LED's - it just uses a few small transistors, no IC's.

I had a quick search, here's the one I was talking about.

http://www.velleman.be/ot/en/product/view/?id=339224

I also found this one!.

http://www.velleman.be/ot/en/product/view/?id=337995