Hi guys

I want to be able to pick up human voice/speech from 3 meter away, can I do that with an electret microphone? what specs should I be looking for in a datasheet?

Or if not practical to use an electret microphone, what else can I use?

Thanks guys!!

 

Sure.
If I remember the numbers right a wm61 is a good one.
you will need to amplify it as they put out very low voltage (mv).
Edit: Part number

 

Hello,

Perhaps the following pages might interest you:
http://sound.westhost.com/articles/microphones.htm
http://sound.westhost.com/project93.htm

And for a home made directional microphone this page:
http://www.bambooturtle.us/ParabolicMicrophone.html

Bertus

 

@bug13
Even a cheap electret will work. I was trying to build a small, high gain, low noise microphone circuit and used all low noise components yet I still had a hiss. I changed everything. I even tested if I could make the noise louder with a cheap electret from RadioShack. The noise was the same. It turned out to be the refrigerator motor 4-meters away. Voice at 3-meters will be fine.

 

Sure.
If I remember the numbers right a wm61 is a good one.
you will need to amplify it as they put out very low voltage (mv).
Edit: Part number

Years ago I built a very high gain electret booster with a TL431 programmable zener - its not exactly Hi-Fi, but perfectly adequate for speech.

For a 5V rail; start with 2k2 from cathode to Vcc, put the mic from sense to GND, hook a 47k pot from K to sense and adjust the output quiescent point - don't forget that K can't swing lower than about 2V. Once you've determined the bias resistance, hang a 1k2 resistor from K and shunt the other end of the resistor to GND with a 100uF cap, take the bias resistor from the top of the cap to the sense input.

If it picks up local radio - put some resistance in series with the capacitor.

 

TL431.. Neat part.

 

TL431.. Neat part.

My very first prototype of that project was with an 80 Ohm speaker and 12V Vcc.

Once I'd included the 100uF capacitor to shunt AC nfb out of the DC nfb that stabilises the operating point - the only way I could prevent howlround was with the mic on a length of twisted pair and placed in another room.

With 12v and such a low Ohm load, the TL431 ran uncomfortably warm, but I'd proven the point and quickly devised a power MOSFET stage to follow it.

 

... I even tested if I could make the noise louder with a cheap electret ...

Do I miss something or you type the wrong word → make the noise louder, why you do that ?

 

My very first prototype of that project was with an 80 Ohm speaker and 12V Vcc.

8 ohms or 80 ohms?
I bought an indoor intercom system long time ago, they used an 8 ohms speaker to replaced the mic, but I can heard the voice from another intercom very clear, even my wife far from the speaker about 100 cm, the speaker still can pick up the voice easily, so I think the amplifier is very important.

 

8 ohms or 80 ohms?
I bought an indoor intercom system long time ago, they used an 8 ohms speaker to replaced the mic, but I can heard the voice from another intercom very clear, even my wife far from the speaker about 100 cm, the speaker still can pick up the voice easily, so I think the amplifier is very important.

8 Ohms would be a bit stiff for a chip in a TO92 package running off 12V.

 

Picking up sound from 3 meters away is not hard. 35 years ago I built a big ear I experemented with several mics then finally after lots of experements I learned an 8" diameter speaker is extremely sensitive to very small sounds I am able to hear people talking 1/4 mile away. I built a 2 IC op amp, both ICs have a gain of 200 with a volume control on both amps.

http://www.talkingelectronics.com/projects/HearingAid-2/HearingAid-2.html

 

Thanks a lot guys, thank you for all the inputs, I believe my problem is solved!!