Hi everyone, I was using fft with electret microphone. I looked the power consumption and it seems too high. So, I searched microphones. Then I realize mems microphone has higher performance then EMC with lower power consumption like uA.
What I want to do, microphone will be really really close and it will detect certain hertz (for example 2 kHz with FFT.) Microcontroller will count how long the signal lasts. (for example 10 minutes 2kHz signal at a day. (it will count only 2kHz signal) )
I watched a video about mems microphone with FFT, he added op amp and capacitors to the breakout board.
I really need to use this microphone lowest current, what happen if I don't add op amp ? can't I detect certain frequency with fft ?
I was thinking of buy Adafruit Silicon MEMS Microphone Breakout SPW2430. It says it is good with fft but it doesn't have op amp.
No additional opamp is included, the output peak-to-peak voltage has a 0.67V DC bias and about 100mVpp (peak-to-peak) when talking near the microphone, which is good for attaching to something that expects 'line level' input without clipping. The peak-to-peak can be as high as 1Vpp if there's a very loud sound.
Thank you for share it but I don't think I understand that clearly.
" which is good for attaching to something that expects 'line level' input without clipping "
I guess 'line level' means is the loudest signal we handle in audio. But in my case I am not trying to handle loudest signal, I want to find how many minutes this certain signal (ex: 3kHz) has been coming.
As you can understand, I am not and expert of these.
Audio Line Level is what comes-out of CD or DVD player, or the RCA analog outputs from your TV. It's rather loosely defined (and consumer audio is uncalibrated) but it's about 1V.
Headphone outputs are also about line-level but they are capable of driving headphones which have lower impedance than a line-input. And, headphone-outputs are more variable because there is always a volume control. (Some line-outputs are volume controlled and some are not.)
Audio outputs are usually a high-enough, and inputs are usually sensitive enough that everything works together. A "real" microphone preamp has a gain control because the signal into the mic varies depending on the loudness of the sound, how close you are to the sound, and the sensitivity of the mic.
The regular 5V Arduino can read 0 to +5V (5V peak-to-peak) so that's a 2.5V biased signal of 1.76VRMS.
Why? The processor and other components draw far more current than the microphone or its amplifier.
I will let this microphone work with arduino and battery. I won't charge it (it will work years), so I was thinking use this mems with deep sleep mode.