Sound sensor help needed

Hello, I have the mic preamp from the attached picture and i need to modified it so that i can use it as sensor for an Arduino. The preamp works, but the output signal is centered at around 2.2V and i need that 2.2v to become 0(at analogRead from sensor pin - i only need the upper "positive" part of the wave to be taken in to consideration). Basically i need to bodify this preamp to be used as a sound level sensor 0(0V on Arduino input)- no sound 1023(5v on Arduino input ) very loud sound

Can anyone help me to modify this circuit? PS: I would like to keep the gain on each stage of the amp if it is possible OMG: How can i attach an image here?

Here is a link to my sensor I can't figure it out what I'm doing wrong

Take R6 and replace it with a pot with the wiper going to pin 3 and the ends to +5 and ground. That should allow you to control the DC level. However it will not turn it into an envelope follower which is I think what you want. For this put a diode in line with the output feeding into an R&C to ground. Then feed that into the analogue input of the arduino.

You are right, i want to create a envelope follower
In my previous attempt i use an RC delay with R=47K and C=100n because i need a small delay (0 will be perfect :slight_smile: ) but instead of a diode i used a 100Ohm resistor.
Regarding the R6 replacement, if i will use a pot then i will have an offset voltage. If no sound (or sound above a threshold) is present the i need my output to be 0, in this case i don’t think it is possible. I am wrong?

I am wrong?

yes you need a DC offset, currently you have a DC offset of 0V with respect to the signal ground. However this signal ground it 2.5V above the arduino ground. therefore you want to have a DC offset of -2.5V. This then would give you 0V for no signal.

but instead of a diode i used a 100Ohm resistor

No you need a diode for this to work.

I've modified the circuit Do you think that will do the job?

Here it is the link

Putting R8 will stop you setting the DC bias as low as you want. Take it out ad give it a try.