WaterTight Ultrasonic Sensor

Hello all,

I am looking for a watertight ultrasonic sensor to make a sonar for my underwater robot (based on Arduino) and I would like to know if there any comercial ultrasonic sensor which I could use for this purpose. Thank you all! Regards! Javi

Its not just a case of being watertight. It has to be in direct contact with the water.

So you need a proper sonar transducer and they are not cheap.

Ultrasound transducer for air will not work for water and vice-versa, the acoustic impedances are many orders of magnitude different.

What prices are we talking about? Do you have a link? :astonished:

Thank you

Google on fish finder. About 130 I think.

May or may not be suitable but its the only one I can think of.

I n this field pretty much everything is custom made.

jups! and do you think it would be possible to make a HC SR04 available for water?

No .It would require a driver crcuit total redesign and custom sensors I think.

It would be expensive and without a demand I cannot see it happening.

Technically possible though.

I was thinking in a more home solution as filling the circuit with epoxy or something like that :roll_eyes: :sweat_smile:

Would some of this work?

https://www.futurlec.com/Ultrasonic_Sensors.shtml

http://www.ebay.com/itm/Ultrasonic-Module-Distance-Measuring-Transducer-Sensor-Waterproof-DC-5V-Voltage-/231458217811

More solutions:

underwater transducer: http://www.rapidonline.com/electronic-components/underwater-ultrasonic-transducer-200khz-plastic-case-35-1810 http://www.prowave.com.tw/pdf/undertx.pdf

Or, making a waterproof ultrasonic sensor completly watertight like this?

https://www.youtube.com/watch?v=Z3vIcjI8Lmc

Regards! Javi

by using an air sensor underwater, you will significantly reduce operational range, possibly completely.

a regular piezoelectric transmitter can easily vibrate the light air particles with little effort, and getting the piezo component to resonate is easy.

doing this in water is much more difficult, as water is much heavier and resonates at a different frequency.

javikomu: Would some of this work?

https://www.futurlec.com/Ultrasonic_Sensors.shtml

http://www.ebay.com/itm/Ultrasonic-Module-Distance-Measuring-Transducer-Sensor-Waterproof-DC-5V-Voltage-/231458217811

No, sensors for air do not work in liquid, we told you this already.

Oh, I thought that transducer was thought for that. My idea is doing an underwater robot which would be able to avoid obstacles.

Didn’t thought it was going to be so difficult to find the sensor.

If you're really determined to make an underwater robot, it might be easier/cheaper to use a raspberry pi and camera for the obstacle detection. It's probably possible to whip something up with opencv that'll detect objects near the bot, and cameras work just fine underwater as long as you find a way to keep them dry and add a nice bright led to light up the area.

Liquid ultrasound is usually much higher frequency to get better resolution (speed of sound in liquids is far higher than in air, order of magnitude, so wavelengths are much larger, for 40kHz the wavelength in air is 8mm, in water 37mm... Ultrasound scans for instance use perhaps 1MHz or so.

I suspect the transducers are just more specialized and thus expensive for liquid use.