Capacitive Rain Sensor

Hello together!

I want to built a capacitive rain sensor for Arduino which can tell me when it rains and how much about (drizzle, normal, heavy rain), maybe 4-5 possible states, depending on the heaviness of the rain.

I currently using a normal eBay rain sensor from China, which is based on resistance but its not very "precise" and does not work with drizzle and oxidizes after one week.

I have found the Arduino "CapacitiveSensor" library and tried to used the shield from the actual rain sensor with a plastic tape on it. I basically works, but the values fluctuate heavily. I used a 1M, 2M and 4.7M resistor between the two pins and a 100pF, 1000pF and 100nF capacitance to Ground.

Maybe you have a better idea to solve this problem, with other components or values or also a complete new circuit.

Thank you in advance for your suggestions!

Before attempting to design and build a capacitive rain sensor, I suggest to investigate how commercial capacitive rain sensors work and how many categories of precipitation are reported.

Here is one example: TeleControlLi.com is for sale | HugeDomains

jremington, thank you for your reply!

I have already seen this document and I know how this sensor works. I don't want such a complex sensor with heater and temperature sensor. I need support with designing or creating a simple sensor.

I need support with designing or creating a simple sensor.

What reason do you have to believe that a "simple" sensor can be made to do what you want? The lack of such commercial options suggests that this is not an easy task.

you could try something like this to see it works
http://www.techlib.com/electronics/raindetectors.htm

modified to just the penny-insulator-nickel with 100k ohm and read with the analog:

// rain_detector
// +-----------A
// |
// ||----+----100K---5+
// +-----------------gnd

penny to gnd
insulator
nickel - analog - resistor - 5v+

see attached to compare rain bucket vs the 6cent sensor

pantonvich:
you could try something like this to see it works
Rain Detectors

modified to just the penny-insulator-nickel with 100k ohm and read with the analog:

// rain_detector
// +-----------A
// |
// ||----+----100K---5+
// +-----------------gnd

penny to gnd
insulator
nickel - analog - resistor - 5v+

see attached to compare rain bucket vs the 6cent sensor

Thanks for this idea!

I will try this, as I have a bit more time! Maybe you can share your code or the formula for this sensor?

sure

#define rain_detector_apin 4
analogRead(rain_detector_apin)

I take a reading every 5 mins and save it to a flat file

also you could put some type of heat on it when it gets wet to make it dry quicker - I've not done that

pantonvich:
sure

#define rain_detector_apin 4
analogRead(rain_detector_apin)

I take a reading every 5 mins and save it to a flat file

Thank you! I thought that you have used the analog value to calculate the "heaviness" of the rain. Maybe I will try to interpret the analog value to get a more descriptive result!

if you look at the plots - it looks like harder rains give lower values - if you experiment with the resistor value you likely can get more range - sticking the 6cents in water gives lower values than what I get from rain events

The Telecontrolli Rain Sensor now is:

By

This explains the theory.

It is relativley easy to make your own sensor by etching a thin ds pcb.
A simple resistive sensor has the wrong footprint for a reliable capacitive sensor

This may fit the bill, i think all the car ones are optical.

rain sensor

Interesting RAIN SENSOR thread!

My car has a rain sensor for the wipers.
It is optical.

This can be had but is a bit pricey.

Used optical car rain sensors are on eBay , and are cheap

  • need a hack to use ?

Look up the Kelvin water-drop generator but don't build one. Just notice how the water drops take energy through induction from the charged loop they pass through.

Actually, they add energy to the system, not take it. It is converting gravitational potential energy to electrical energy.

I'm not sure how this helps, though.

The more rain that falls through the loop, the more change. There's probably a circuit that will hold a voltage dependent on how many drops pass through over time.

That's not really how a Kelvin water drop static charge generator works.

polymorph:
That's not really how a Kelvin water drop static charge generator works.

You're right. Did I say to build one?

Hint, read 1st sentence of reply #15.