I am onto a simple project with Arduino, SR04 and a buzzer for "Car reverse parking assistance". The aim here is to make a buzz when the car gets too close to the objects.

I was thinking what if it's raining when a person is driving (assuming I somehow achieved to water proof the sensor) - will the buzzer make continuous sounds?

Is there any alternative solution for ultrasonic sensors?

  • 1
    Try it and see? Wrap your sensor in something waterproof like a latex glove finger, and then put it in the rain. See if you get false readings. Or just take it into the shower with you. ;)
    – Nick Gammon
    Commented Aug 25, 2015 at 7:09
  • @NickGammon Wouldn't you just be sensing the distance of the latex from the sensor?
    – Majenko
    Commented Aug 25, 2015 at 10:23
  • Yup, @Majenko is right!
    – Lokanath
    Commented Aug 25, 2015 at 10:25
  • 2
    @narzan I think the person asking the question was referring to water droplets in front of the sensor (assuming i somehow achieved to water proof the sensor).
    – Gerben
    Commented Aug 25, 2015 at 19:00
  • 2
    I tested the idea of covering the sensor with latex and can confirm that it does not work. :)
    – Nick Gammon
    Commented Aug 25, 2015 at 22:04

3 Answers 3


will the buzzer make continuous sounds

If you mean the sensor will detect the rain drops in the air Nop it's tiny to read it in the air But if there is drops on the sensor your sensor will not gives you the right reading

There is a water proof ultrasonic sensors available.

I am working on water level devices, after long path of searching in different ultrasonic sensors and after I tried a lot of method like using water proof Cloth, I found the best way is using water proof sensors PLUS water proof cloth.

water proof sensors work perfectly in high humidity but at the same time if there is a water drop on the sensor the reading will be different, and for that some cars manufacturers used not only one sensor, to avoid the errors. and calculate the differences.

enter image description here

The left car used old technology with separate sensors, but that's make errors the only good thing was to detect more things, in the next generation they mix them together.

water proof cloth will make the water drops not stuck at the sensor, but you will need to replace it every 5-6 months. "in your case because the sun will destroy the cloth" in my case and because my sensor inside tanks that's will least more.

I tried to spray the sensor with a different material to make my sensor not catch any water drops, it dose not work too.

And to make my cheap sensor water proof, I tried to use ceramic layers, and that's not work too, they use it with ultrasonic fog maker, these layers not work with cheap ultrasonic sensors, it's need a lot of power to vibrate it and different frequency. and of course you need to replace the layers "depending on the environment"

If you find ultrasonic car sensor with special material for water drops just let me know, I am searching on that too.

NOTE These days car manufacturer use different ways, in the past the cover was vibrate itself and made from aluminum, now they cover it and make different filters to ignore the plastic cover, How?! maybe it's different plastic or material maybe they find away to vibrate the plastic! sorry I could not find the secret.

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    thanks for sharing the information:) ,,,,As you said i will use two sensors and compare among the data to make decisions ..
    – Lokanath
    Commented Aug 25, 2015 at 11:25
  • Ya that's will be more better :) you are welcome
    – Narzan Q.
    Commented Aug 25, 2015 at 11:28

It would probably be easier to use an IR distance sensor. That would also be easier to waterproof.


Just a thought, a lot of cars use them, why not try your local salvage yard you may be able to get them on the cheap.

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