I have this up on a breadboard, with a 1N4001 diode, according to the diagram, not the drawing (misplaced diode). I have omitted the 1000uF cap across Vin/GND, didn't have one.
I'm getting a nice amplified signal on my scope from pin 5 of the LM386, but nothing after the diode.
Ideas? Have anyone tried this? Which diode did the designer actually have in mind? Do I need to change the values of the caps/resistors?
Do you have an alternate design? I have LM386's available + a few handfuls of transistors. And there's a bit of urgency, so waiting for delivery of components is undesirable.
If we can't get the circuit to work, do you have an idea to do the integration/envelope in SW on the Arduino?
The application is "how loud is it, on an arbitrary scale, right now". I need to catch peaks of ~100ms duration.