One for the plumbers...

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1

I’ve been pointed at the following circuit for amplifying the output of
an electret mic and smoothing it before feeding it into an A2D to get an
indication of sound level - integrating the electret output for
somewhere between 10-500ms is probably about right. The electret will be
biased with 5V and then through a cap before being fed into this
circuit, as normal.

Question: How do I calculate the values of R1 & C1?

I’m aware this could be done with op-amps but I don’t need audio
quality, just a smoothed indication of volume and size/part count is
more important.

Thanks,

Alan Burlison

miller.png433×517 14.8 KB

2

Grumble…I am not a plumber!

I will respond presently

AlexOn 15 May 2014 14:39, “Alan Burlison” alan.burlison@gmail.com wrote:

I’ve been pointed at the following circuit for amplifying the output of an
electret mic and smoothing it before feeding it into an A2D to get an
indication of sound level - integrating the electret output for somewhere
between 10-500ms is probably about right. The electret will be biased with
5V and then through a cap before being fed into this circuit, as normal.

Question: How do I calculate the values of R1 & C1?

I’m aware this could be done with op-amps but I don’t need audio quality,
just a smoothed indication of volume and size/part count is more important.

Thanks,

–
Alan Burlison

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3

Grumble…I am not a plumber!

I know, but I also knew the subject line was guaranteed to get you to
read the email :wink:

I will respond presently

Thanks, it’s appreciated :slight_smile:

Alan Burlison