On Tue, 18 Oct 2005, Neil Baylis wrote:

> Hehe, see the other thread about the fried PIC. Your friend is probably
> using a wall wart, or some such thing. Unregulated power. The hum, is
> probably ac line frequency ripple that's on his power supply.
>
> Neil
No, It's not a PIC pin. It is a CTS or RTS pin from a
bluetooth device. The pin can be set high (4.5V) or
low (0.1V). But I would like to prevent the hum in the piezo
when it is low, by blocking the 0.1V.


>
> On 10/18/05, Kevin <kben@universal.dca.net> wrote:
> >
> > A friend has a circuit that turns a pin hi 4.5V to low 0.1V,
> > current is about 10ma. He has a piezo speaker connected to
> > the pin and to ground. So when he sets the pin high
> > he wants the piezo speaker to buzz, and when he sets
> > it low he wants it off. However, when it goes low it's not
> > at 0V so their is a noticable hum from the piezo. What's the
> > easiest way to keep the pin at OV, to keep the piezo from
> > humming when it should be off.
> >
> > Thanks for any suggestions,
> > Kevin
> >
> >
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>
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