Just connect the diode in parallel with both the piezo and the storage cap
"+ve" pulses will charge the cap and "-ve" ones will pass through the diode.

Richard P

> -----Original Message-----
> From: Paul B. Webster VK2BZC [mailto:paulb@MIDCOAST.COM.AU]
> Sent: Monday, April 17, 2000 9:45 AM
> Subject: Re: [OT] More on piezo-electric generation please
>
>
> Russell McMahon wrote:
>
> > I say
> > 1 diode or 4
>
>   I've jsut been through this argument with Graham Zimmer
> (off-thread -
> it seems we should perhaps have copied it on-thread).
>
>   Produce your circuit based on one diode, please.
>
>   Before you answer though, do consider - the piezo (pee-ate-zoh)
> element is actually a capacitor.
> --
>   Cheers,
>         Paul B.
>