> I would use a opamp configured as a comperator to measure the resistance
> between two electrodes in the Plant pot. By using this approach you will
> have a 0 or 5 v signal to the 12c508, and you can add a pot to adjust the
> sencivity of the moist sensor.
>
> Regrads Henrik Holmgaard
A LDR arangement could be fitted to this opamp configuration to meet
your demand 'not to beep when it is dark' Cool, just switch the light
off when it squeels for water...........
Regards Cassie.
>
> > -----Original Message-----
> > From: Benjamin Petersen [SMTP:benjamin@MARK-INFO.COM]
> > Sent: 10. maj 1999 09:47
> > To:   PICLIST@MITVMA.MIT.EDU
> > Subject:      "Plant out of water project"
> >
> > I have an (old) idea for a new pic project.
> > I would like to attatch this device to a plant and make it beep when the
> > plant needs water.
> >
> > I was thinking about using :
> > 1 3v litium batt
> > 1 PIC12c508
> > 1 Pizo-beeper
> > 2 metal pins pluged into the plants pot (or what ever you call it)
> >
> > I would like to make some kind of A/D converter, and as far as i can
> > recall
> > it can be done with a cap and a res.
> > And something with pulsing an output and reading an input.I was thinking
> > that the water alarm should NOT beep during the night, messured either by
> > an
> > internal clock or by a photosenser. Dryness alarm should be dynamic.
> >
> > When this project is done it will ofcause be public.
> >
> > Regards
> > Benjamin Petersen
>