Hi,
in the catalogue stands:

input clamp current: +/- 20 mA. It means it is enough to put such
resistors which limits to this value, i.e. instead of my first suggestion
2 x 250 ohms must be sufficient (2 x 5 V = 10V, 10V / 500 ohm = 20 mA). I
think here won't suffer the volume.

Regards,
Imre


On Sat, 30 May 1998, David VanHorn wrote:

> >I think that what David is suggesting is right.  Perhaps one could think of
> it
> >as a first approximation of a sinewave that is being sampled at the peaks
> and
> >the zero-crossings?  Since the slope of the sinewave at the zero-crossing
> is
> >more steep than the slope at the peaks, the 0-0 period could be very small
> in
> >respect to the period of the signal.
>
>
> Interesting, that wasn't my intention, but that is the result.    I've
> scoped the lines
> on a piezo driven with the "wrong" cadence, and I have seen the voltage
> doubling
> effect working. It wasn't double, as it was dumpng into the uP protection
> diodes,
> but that's the whole point. We don't want to put much current into those
> diodes,
> and the basic limit here is the uP's own output current.  I think if you ask
> your
> uP vendor, they won't reccomend dumping 20mA into the protection diodes :-P
>
> >I have not used this idea, but I will incorporate it the next piezo element
> that
> >I drive.  Thank you, David.
>
>
> :)
>
>
> An additional note, someone suggested that impact or vibration could cause
> the
> same effect, and I agree.  I'm leaning twoard a pair of zeners out there.
>
> A magnetic beeper wouldn't have as many potential problems, maybe that's a
> better
> path.
>
>