The OP may build a resonant circuit using an inductor and the
capacitance of the piezo.
At the resonant frequency the voltage will build-up and it may become
very loud.

Isaac




Em 1/2/2011 21:53, IVP escreveu:
>> My first thought is "will +/-24V be enough"? If so, can you run the
>> piezo in bridge mode
> There's an example of that (Fig 73, p24) in the OPA454 datasheet
>
> "Bridge Circuit Doubles Voltage for Exciting Piezo Crystals"
>
> http://focus.ti.com/docs/prod/folders/print/opa454.html
>
>> If not, and you really need +/-30V supply, can you wind your own
>> magnetics? If so, and it doesn't need to be very efficient, a two
>> transistor astable multivibrator type of upconverter would be pretty
>> easy.
> Most switchmode controllers have application notes for boosting DC
> to higher positive and negative supplies
>
> eg the cheap old MC34063
>
> www.onsemi.com/pub_link/Collateral/AN920-D.PDF
>
> Fig 26, step-up  Figs 33/34, inverting
>
> There are plenty of others, some quite efficient if that's important
>
> Basically any oscillator can be used to switch an inductor in and out
>
> Joe

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