Hi everyone , i m on a project that record sounds. i am using arduino nano. my device successfully record sound with Max9814 sound module. But unfortunately didnt record the microphone which i send you picture bellow. i plugged a0 and 3.3v to mic. i also try 5v input. and try different polirity. i can record waw file but only noise. i can hear parazites when i disconnect vcc and connect. but no voice. my questions are
1- do u have any idea why it didnt work?
2- is there any easy way of test way of new microphone ? because i plug some cable ro mic, then record then un mound sd card go pc and listen. it takes time. maybe serial plotter or something else.
thank you
No, because it's not entirely clear what you're doing. More specifically: what kind of Arduino board and what does the full sketch look like?
It really helps if you have more information about the microphone module. Apparently you took this from some piece of equipment; that often has some clues as to how (and if) you could use it.
Do you have any specs or any more information for the mic in the picture? Is it a "computer mic"?
I assume the "sound module" has a built-in mic? (The MAX9814 is just an amplifier chip.)
You do need a preamp. Microphones put-out a few millivolts and you need about 1V. I see a couple of transistors on that circuit board but I'm not sure if that's a "regular preamp" and of course I don't know if it runs from 3.3V or how it's supposed to be hooked-up.
NOTE - The input to the Arduino also has to be biased because the Arduino can't read the negative-half of the AC audio waveform. The bias is built-into most "sound modules" but not built-into a standard mic preamp. That's NOT your problem right now... Without the bias, you'll still get sound but it will be distorted.
I can see an electret condenser mic element (I think) in the center of the PC board. You should be able to use that with the MAX9814, bypassing the unknown circuit board.
Telephones have their own requirements, and there is about 40VDC on the telephone line, which would have been used unless the phone had it's own power supply. Of course cordless phones have a battery.
i dont want to spend money to buy max9814 and also dont want to lose time for replace modules. Maybe there is a way to use this orginal telephone micrapohone. i can use its speaker. its ork fine with 5 v dc. but i cant run the micraphone.
Like I said, you need a preamp!!! You can build one with an op-amp (but IMO it's not worth the time & trouble).
It doesn't have to use the 9814 chip. Here is a schematic. This is an "Arduino compatible" design with a biased-output (1) but it doesn't have adjustable gain. You can change the gain by changing the values of R4 & R5 (2) or you can add a potentiometer, etc.
Almost any op-amp will do but the schematic shows "rail-to-rail" op-amp so you can get the (nearly) 0 to +5V swing.
(1) R2 & R3 make a 50/50 voltage divider to provide the 2.5V bias.
(2) The gain of an inverting amplifier is calculated as R5/R4.
