microphone to PIC

hey,
I'm trying to connect a microphone to PIC chip to start a timer but Im a bit unsure of what I'm doing. I've got a circuit which will amplify the signal and then convert it into a square wave, which will then go to the PIC.

I'm wondering if it's ok to use a dynamic microphone as the circuit will be powered by a 9v battery and do I need a pre-amp AND another amp before connecting it to the PIC?

Any other Qs or info would be cool too.

Cheers

The output from a microphone is too low to feed a PIC unless it is inside a loud drum. So a preamp is usually needed.
You might need a circuit to limit the voltage to 0V to +5V.

If you use a dynamic mic then you need a preamp circuit designed for it. An electret mic needs to have a different preamp circuit.