amplifieraudiocondenser-microphonemicrophone
So I am using MAX9812 amplifier to build a microphone module, but from the pic you can see it requires 3 wires, vcc, ground and output.
I was thinking to wire Vcc with output to get rid of one wire, making it a 2 wire system, is this possible without losing the amplification?
Thanks for any help.
Do NOT tie any of the speaker pins of the BT module to ground! This will likely damage the module.
You can wire the speaker and microphone as shown, but as you say, you'll lose half the drive voltage.
As an alternative approach, you could use a 1:1 audio transformer; connect one side to the two speaker terminals of the BT module, and connect the other side between ground and your speaker.
As far as I understood, you are trying to make some kind of a sound level detector, which will let you detect if there is a sound with a certain volume or not. You can do this with minor changes to the schematic you have. But before that, you should understand the circuit.
Let's break that circuit down. First of all the part with the microphone.
R1 is for supplying power that is needed by the microphone and this is called biasing the microphone. A microphone generates an AC voltage, which is sometimes negative and sometimes positive and it changes most of the time. Think of a sine wave. But remember, we had some biasing to it which is a DC voltage. We have to take that out and give only the AC voltage to the amplifier. And doing this is easy with a simple, single capacitor. A capacitor does not let the DC to pass, but lets AC pass easily. We have blocked the DC portion of the voltage on the electret microphone.
Now, let's look at the amplifier itself. Imagine that there is nothing else but the below schematic:
In this configuration, the transistor is biased to be in the linear region. It is in the edge of being turned ON or turned OFF, but it is neither of it. If it was fully ON, it would be saturated. If it was fully OFF, it would be not conducting at all. But it is in the middle, which is called the linear region.
When it is configured like that, if you touch (not literally) to the base of it, creating a small change, the output will be changing largely. This is what amplification called. You can beg Google for more detailed information.
What if we combine the two circuits mentioned above. A biased electret microphone with a capacitor will output small changes with respect to sound. The transistor will amplify these small changes so they can be viewed easily:
Notice that I have changed C1 to 1uF. You can use values up to 100uF. You will probably need electrolytic capacitors. Also, notice that there is no more an output capacitor. This means that you will have an output voltage somewhere between 0 and 5 V, depending on the sound level. If you have an oscilloscope, view the waveform on the output. If you do not, try lighting an LED if the analog read is higher than, for example, 750. Experiment with different values than 750, then report me the results.
Best Answer
It's called phantom powering and works fine for balanced stage microphones and will work OK for short runs of cable connected to an unbalanced microphone but be aware that noise will eventually become a nuisance because the unbalanced microphone.