I read your thread about getting a piezo buzzer to work on the pic. This I have done. However what I don't understand is why you can't drive the piezo very loudly through a mosfet. It doesn't really work at all just a faint noise. however if a 1k resistor is connected in series with the piezo it works ok but not that loudly. I think the frequency is OK. driving a loudspeaker through the mosfet works fine. There must be something about driving a piezo i don't understand. Any help gratefully received.