allanhurst:
Try it my way with a signal generator. And do some sums .And download and learn to use simulation programmes such as 'PSPICE' or 'LTSPICE'.
You'll find them very useful.
Allan
edit : you may find the enclosed driver useful - put the inductor/piezo where I show the loudspeaker.
Ok good news! I got it working with the signal processor, and i finally understand the entire setup, and how the capacitor, inductor and waveform signal processor work together. Managed to get around 16-17vAC from the 3v power source - Amazing!! 
Works like a charm, however when i try to move from the waveform generator towards a transistordriven circuit i get into trouble. I've made the setup as shown on the attachments, however it seems like i only get power from the transistor-gate and nothing form the actual DC power source. How can this be?
By the way, thanks for the tip with simulation-software, it has saved me lots of hours!
