Author Topic: Waterproofing the Sonar Mote  (Read 1780 times)

designDemon

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Waterproofing the Sonar Mote
« on: October 11, 2018, 02:00:21 PM »
Hey

Has anyone had any luck on waterproofing the HC-SR04
sensor? The Sump pits here have a 8 inch thick solid
concrete lid, so the entire mote has to be placed inside and
even though the chances of the sump pit overflowing are
rather rare, the humidity inside >95%.

Also are there low power waterproof alternatives available for
the HC-SR04 with a range of 10-20ft? I've had a look
at the one's form MAXBOTIX, but they are prohibitevly
costly. Looking for something in the sub $20 range.

-Karan


Felix

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Re: Waterproofing the Sonar Mote
« Reply #1 on: October 11, 2018, 04:05:12 PM »
Hey Karan,
The SonarMote kit from LPL has this acrylic lasercut case, you can pretty easily "waterproof" it with various more or less intrusive methods, but  I would still not consider it a long term proofing. I service my sump pump SonarMote about every 1-2 years, sometimes I find small amounts of corrosion that I clean up. Then I re-tape it all around in clear tape but not around the sensor openings.

The sonar sensor itself cannot really be waterproofed, and it has a limited range, works at 5V (requires a little booster, included on the SonarMote board).

I do not know of another reliable low power sensor to reach 20ft. I would try making some kind of resistive sensor for such an application.

Felix

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Re: Waterproofing the Sonar Mote
« Reply #2 on: October 12, 2018, 04:23:11 PM »

TomWS

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Re: Waterproofing the Sonar Mote
« Reply #3 on: October 13, 2018, 10:54:31 AM »
Just saw this on tindie:
https://www.tindie.com/products/jbruell94/i2c-liquid-level-sensor/
Good find! I've thought about making one using air pressure as the sensor. If anyone gets this let us know how well it works.  Note that the code would have to factor the density of the liquid.

Tom

Kilo95

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Re: Waterproofing the Sonar Mote
« Reply #4 on: October 15, 2018, 08:31:57 AM »
I replace the sonar sensor about every 10-12 months. my water softener back washes into my sump and some of the salty water splashes up on the sensor. so eventually there is some corrosion.

As far as waterproofing...what about making a wire pigtail so that you could leave the Moteino/battery outside the sump and place the HC-SR04 inside the sump? Just a thought.

Felix

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Re: Waterproofing the Sonar Mote
« Reply #5 on: October 15, 2018, 10:56:24 AM »
I replace the sonar sensor about every 10-12 months. my water softener back washes into my sump and some of the salty water splashes up on the sensor. so eventually there is some corrosion.

As far as waterproofing...what about making a wire pigtail so that you could leave the Moteino/battery outside the sump and place the HC-SR04 inside the sump? Just a thought.
Are you replacing just the HC-SR04 or the whole mote? Surely you shouldn't have to replace the whole thing... in my sump pump I do see some rust building inside the sonar sensor but I see no difference in readings and so I did not replace it so far and It's been in use for years.

And yes you could totally use a dupont wire to extend just the HCSR04 sensor in the hazard area rather than the whole mote.

wile1411

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Re: Waterproofing the Sonar Mote
« Reply #6 on: October 15, 2018, 08:11:11 PM »
Thought I'd add something to the conversation from my research. I may not help with the sump overflowing and water getting into the sensor for you guys.

I've only just got my sonarmote and have been racking my brain with trying to work out how best to use it to measure the pool level while it's mounted in the filter box. Similar issue in that I didn't want the electronics / HCSR04 sensor getting wet and it'd be a humid environment sitting above the water in that box. Other factor is that when people are in the water, the level will get a bit choppy from the both the displacement of people in the water at various times, as well as their movement creating waves.
 
Finally stumbled onto some clever lateral thinking person who seems to had an idea on how to enclose the unit and still have it perform it's measurements using a ping pong ball captured in a PVC pipe.
Old 2004 project link (not mine)

I figure it would stop the majority of the splashing risk I was worried about when people are in the pool.

Kilo95

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Re: Waterproofing the Sonar Mote
« Reply #7 on: October 16, 2018, 07:38:00 AM »
Felix, i replace just the HC-SR04. I get a salty crust on the sensor. It doesn't give nice crisp readings on the gateway anymore. i replace just the sensor and that fixes it.

With the ping pong ball....How do you get good readings? I tried using PVC before but the HC-SR04 wasnt giving accurate readings                   

wile1411

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Re: Waterproofing the Sonar Mote
« Reply #8 on: October 16, 2018, 09:07:43 AM »
ah good point. Sorry  :-[  I hadn't thought about how the echo reflection off the side of a pipe might effect the reading. That makes sense seeing as the example was using an IR sensor for that project.

i670

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Re: Waterproofing the Sonar Mote
« Reply #9 on: October 17, 2018, 08:29:28 AM »
I got tired of replacing corroded HC-SR04s and went with the JSN-SR04T.  The version 2 runs fine on 3.3v, it has a single transducer and seems quite weather resistant.  I power it from two output pins that are switched to save power.  No issues in over two years outside 1km from the Southern Ocean with a fair bit of salt in the air.

dave