On Thu, 26 Aug 1999, John Waters wrote:

> Hi All,
>
> I have built an automated lawn spraying system for my backyard. A PC is used
> to turn ON and OFF the water valve periodically according to a preset
> schedule. The problem now is, it may sometimes be raining during, or shortly
> before the spray time, which would simply waste water. Is there any
> commerically available rainfall detector that could be interface to my PC? I
> want to use it to stop unnecessary spraying. Or, I could build my own
> circuit for doing this, does anyone get such a circuit?


Stephen Bolt in the Netherlands has a *great* site --
http://www.xs4all.nl/~sbolt/e-index.html

One project is the "Green Thumb" --
http://www.xs4all.nl/~sbolt/e-groeneVinger.html ; it uses a very simple
circuit to flash a LED when a plant needs water.  Doesnt need batteries!

For your circuit, you'd prob write the LED into an input port, or maybe
trigger a solenoid directly.


- j