Rain Detector [Embedded]

From: scilent-project on 26 May 2006 07:17

Hi
For final year project,I want to design a rain measurement device which
can be read through parelle port of a PC.
All ideas on this topic are cordially welcome.

thanks in advance.

From: Peter on 26 May 2006 08:38

From: Roberto Waltman on 26 May 2006 09:39

"scilent-project" <Triblesix(a)gmail.com> wrote:
>For final year project,I want to design a rain measurement device which
>can be read through parelle port of a PC.
>All ideas on this topic are cordially welcome.

Please define more precisely what do you mean by "rain measurement".
Do you want just to (a) detect it is raining or (b) measure the amount
of precipitation?
There are many simple solutions for (a), a simple switch activated by
the weight of water collected in a small vessel, detecting the change
in conductivity of "something getting wet", etc.
(b) will require collecting rain water and measuring it somehow.
Weight, height of water in a container of known dimension, pressure
generated by the collected water, changes in light transmission
through the water, etc.

You should focus first on the physics of the problem. Once you know
what to measure and how to measure it, the interface to the parallel
port will probably be the least important part of the project.

From: Tom Lucas on 26 May 2006 09:43

"scilent-project" <Triblesix(a)gmail.com> wrote in message
news:1148642231.507115.158470(a)j33g2000cwa.googlegroups.com...
> Hi
> For final year project,I want to design a rain measurement device which
> can be read through parelle port of a PC.
> All ideas on this topic are cordially welcome.
>
> thanks in advance.
>

1) PC sends constant stream of data from Parallel port
2) PC is left out side.
3) Rain kills PC
4) Stream of data stops. Rain detected.

Seriously though, I'd be inclined to use the serial port because it is
simpler and needs fewer wires. Use USB and get power thrown in for free!
However, the PC end is the least of your troubles (but don't leave writing
the driver until the day before the project is due because it can take a
while)

As for the detection, the water level detection in the Industrial Boiler
Control I'm working on uses capacitance probes and is pretty sensitive. They
work by using an oscillator whose frequency varies with the capacitance of a
probe dipped in the water. Measure the frequency - know the depth. The
concept will probably work with a large flat probe to be spattered by rain
instead of a long thin dipper. Or you could have a bucket with a dipper in
it.

Of course I have seen simple rain detectors which are just two wires beside
each other. When a drip bridges the two then the circuit is completed.

From: Oscar on 26 May 2006 10:49

> Hi
> For final year project,I want to design a rain measurement device which
> can be read through parelle port of a PC.
> All ideas on this topic are cordially welcome.
>
> thanks in advance.

Look at web sites for commercial irrigation systems. Most of them have a
rain detector nowdays to prevent watering when its raining or has rained
recently. Get some ideas from them and then design a better one.
Conductivity through collected water and periodic cup dumping are common.

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