Hi Mike!

Thanks for the post... I worked on a very lengthy reply and then lost it unfortunately =(...
The main pointers of that message were:

I'm looking for a small solution that can run on for example 3.3 volt, and haven't been satified with inverted pin output which is shown so often

Unfortunately I came to the conclusion that I don't understand enough to design a flyback solution in the limited time I can currently allocate.

I checked several resources, and then availability and size of split smd coils and their pricing. I had doubts as to whether there was much of an advantage of using a flyback converter here..

I had uncertainties on whether I could build the coils myself (aircoil? pcb inductor?)

Reading the schematics I had several difficulties as well...
(for example @ http://en.wikipedia.org/wiki/Flyback_converter) I was unsure how the split inductor should really be connected to the PCB.

PCB Die bonding made close analysis of the dissected circuit difficult.

Thats why I decided to follow a different route at the moment....

Anyway, in my search for a reasonable solution I did find some very nice chips from maxim (~1$) which I indend to try out. For example the MAX9738...
These also typically have 14-16VP-P so I hope my RS232 method will work... I do hope it will work because many hobbyists already have that chip at home.

I also figured the max3232 solution may also offer protection from Voltage spikes (from trauma or intended tapping) of the piezo (sensing by linking rs232 input and RS232 output).

Here some interesting links:
http://www.instructables.com/id/Extr...ep14/All-Done/
http://video.google.co.uk/videoplay?...7327995034061#

I'm still missing some caps for my test but I will post soon...

regards,
Michael