Tats à Rotterdam

I have much problem trying to get a sound signal into the Arduino. I have to say I feel a bit frustrated by this: we're getting closer to the end of the workshop and the first part of the project isn't working at all. I'm thinking about changing my sensor: audio input is fucking tricky, I realize now.

Anyway, the images attached to this post show the circuit I've been building, with operational amps. The problem is there are many places where the thing can break: type of microphone, size of the condensors and resistors, voltage, etc. so it's really hard to debug, and I don't understand well what is going on.

Here is a link to a discussion about inputing a microphone into a Arduino.

Here is an extract of an IRC chat I had on the #arduino channel today:

johnseb: hi everyone
[21:27] johnseb: has anyone here ever tried to get audio input in a arduino?
[21:28] mumptai: hi
[21:28] johnseb: i just can't get the audio loud enough for the arduino to recognize variations
[21:28] mumptai: the AVR has a may. sampling rate of about 15kHz, not that much
[21:28] mumptai: you need an amp
[21:28] johnseb: well it will be enough for my app.
[21:29] johnseb: yes i'm trying with an op amp
[21:29] johnseb: but it still feels like the audio variations are not amplified enough
[21:29] mumptai: a few transistors or one/two opamps might be sufficient
[21:30] mumptai: it might be the best to adapt some other circuit for you needs
[21:30] mumptai: there are some guitar tuner circuit out there
[21:31] mumptai: and switches reacting on handclaps
[21:31] mumptai: maybe even ultrasonic rangefinder might have an appropriate pre-amp for the mic
[21:32] mumptai: microphone pre-amp might be the best thing to google for
[21:32] mumptai: and watch out for the type of mic you are usung
[21:32] mumptai: ehh, using
[21:33] johnseb: mumptai: yeah i was told about dynamic mic vs condensor mic..
[21:33] johnseb: .. but i just dunno how to differentiate them
[21:34] johnseb: oh ok.. condensor mics need a power supply, heh?
[21:34] johnseb: so the mic i use is dynamic
[21:34] mumptai: iirc, yes
[21:34] johnseb: hmmm... well.... not sure actually
[21:34] mumptai: just compare it to picures in an cataloge?
[21:35] mumptai: small aluminium capusules are probably not the dynamic typer
[21:35] mumptai: -r
[21:36] johnseb: fuck... it's hard to tell actually
[21:37] johnseb: is there an electronic way to test it?
[21:37] johnseb: i mean, to know which type it is?
[21:39] mumptai: there probably is, i don't know it