I think, there is no fundamental difference between driving a pi想o from one
pin or from two pins in counter phase. Only, cause of the doubling of the
voltage, the problems are bigger.
I have thousands of 4093 running on 9V driving pi想o's this way with no
problems.
Is it possible that troubles come with the use of big pi想o's as used in
alarm systems?
Is there any other experience driving small pi想o sounders this way?

> -----Oorspronkelijk bericht-----
> Van: pic microcontroller discussion list
> [mailto:PICLIST@MITVMA.MIT.EDU]Namens Dave VanHorn
> Verzonden: zondag 12 september 1999 22:20
> Aan: PICLIST@MITVMA.MIT.EDU
> Onderwerp: Re: RE: RE: Driving a pi想o sounder
>
>
> Subject: RE: RE: Driving a pikzo sounder
>
> This is one way to have real fun with your micro.
> Driving a piezo from a micro usually follows a pattern..
>
> One lead grounded, one lead to the micro. Too soft.
> Both leads to the micro, driven in opposition.  Nice and loud.
>
> Then the strange behaviour begins.
>
> After a while, you notice the similarity in the schematic
> between a charge
> pump voltage doubler and your piezo element and port pins,
> and you realize
> that every time you flip the piezo, you are flirting with SCR
> Latchup or
> glitching your micro.
>
> Then you drive it through a pair of HC inverters at least,
> and get "happy
> beeps"
>