I'm using Arduino Nano for my Acoustic Project. I'm using the RF24 Library for audio transmission. I'm using a Max4466 microphone and It has a DC offset of Vcc/2. which 3.3/2 In my case. I tried to use a bandpass filter with 680uf and 47 ohm (high pass filter stage) and 10uf and 47ohm (low pass stage) but that introduced more noise to my Arduino. I'm asked to have a 0 DC offset for my recording purposes. Is there a reason why do I have so much noise from filters? Is it the Analog Input perhaps not accepting AC Voltage?
It's Nano v3.0. But I meant that nano will be only used for transmitting the signal but at the same time, that signal will be shared to a DAQ which needs to be AC Signal with a low pass filter. The Max4466 has its own amplifier and outputs a maximum 1.65 V DC voltage without noise. So I thought that Analog Input A0 can accept AC signal as well? I could be wrong that is why I'm asking
You shouldn't get noise but you can get distortion or other issues...
The ADC doesn't read negative voltage, plus the Arduino can be damaged by negative voltages. That's why the microphone board is biased.
As you may know, the high-pass filter will remove the bias. And depending which filter comes first you can end-up with "floating" undefined DC on the ADC's input.
The bias can be subtracted-out in software. If you need a high-pass filter for other reasons you'll need to add-back the bias (one or two more resistors).
Also, note that 47-Ohms is low for most "signals" and the 4466 probably isn't rated for 47-Ohm loads. (I haven't looked at the specs.)
Yeah correct.. I'm getting distortions. How to add back that same bias after applying the HP filter? can you show a simple schematic? Otherwise I think I'll have to only use a LP filter in the end..
Thank you but this thread is talking mostly about coupling audio without an amplifier. There are few who are using op-amps but I don't get the thread. My question is how to add bias after the HP filter or after the AC coupling stage
The thing is he saying that It's not supposed to be used with amplifier because it can output more voltage. So I'm not certain if I'm supposed to use it or not. the output of amplifier has DC offset of 1.67 , a minimum of 1 V, and a Max of 2 Volt for loud noises. Is it safe to apply it on amplifier?
Because it can output more voltage than what? and what amplifier? This thread is just going to frustrate potential helpers and go on and on without real answers, unless you really show solid information about the hardware.
Please, a complete, labeled wiring diagram showing all modules, and schematics of any custom circuits you have incorporated.
That's a 5V device, so Vcc/2 would be 2.5V, not 1.65V. and it's really doesn't have the speed/memory to deal with audio signals with more than lousy quality.
That is the issue here. I can't provide a schematic since I don't use any programs to make schematics. Can you recommend me with a free schematic designer programs?
Not for here you don't. If you want to delay your solution for no good reason, that's up to you. Do you have some mobility issue that prevents you from using your hands? Also do you really need a recommendation from us? You can find one by Googling.