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I am not a smart person, but I do like performing a bit of science

cstanton

It's too warm in the United Kingdom, so I figured I'd invest in a fan/humidifier combo. 

image

The downside to this hardware, is that it will burn itself out. There's nothing detecting when the water reservoir doesn't have water in it. It's convenient enough, 3 modes to the fan, 3 levels of humidifier, battery, and USB rechargeable. 

So I figured, why not try to detect how much water is left in it with the hardware I have available? I couldn't wait for looking up too much detail or ordering parts from an online store.

I've no idea what I'm doing, so I figured, let's stick a couple of paperclips in there and connect it to an arduino uno.

image

So I read a bunch of values, do some buffering with an array, average them out. I get a very rough sine wave into the analog pin.

And then I notice the pattern, the water's low, the values are higher, the water's high, the values are lower. Setup some ranges, great.

Then I realise what I'm measuring when I turn off the humidifier, the paperclips are picking up the electrical noise from the humidifiers in the water

image


Not quite how I expected to measure if there's water left, but it appears if it's working harder, it's easier to pick up the noise, water isn't the best electrical conductor after all.

Still, I'm sure I should find a better method, but it is a small reservoir, I considered 3D printing something to be able to screw a bottle in to expand it a bit more though.

What do you think?

  • Hi ..

    As we say in Boston Massachusetts USA, your "Wicked Smart" and your "Wicked PISSA" tooJoy....  Seriously I would have never thought of that.  

    I found an easier way to measure water level by using a groove water sensor and a Arduino MKR WAN 1300

    I used the sensor for a design challenge I did here on the community a few months back.image

    The part is

    • Grove - Water Sensor   SKU 101020018 
    • I purchased mine from MOUSER for $2.13 (USD)image
      • Grove - Water Sensor detects the presence of water using exposed PCB traces.
      • The sensor is made up of interlaced traces of Ground and Sensor signals.
      • The sensor traces are weakly pulled up using 1 MΩ resistor.
      • The resistor will pull the sensor trace value high until a drop of water shorts the sensor trace to the ground trace

    You can use the  sensor, the opposite way I did. you can test the sensor to detect no water dry = 1. Hopefully, it will sense the dryness before the unit burns itself out !!!  It does use a groove connector but you should be able to connect a jumpier from one end of the groove connector to the digital pins on the Uno. You then can do a DigitalRead() to check the value as I did

    the CODE is  in MKR_LoRa_Sender_E2.ino Which you can view in my comment under my blog in the Design challenge series at BLOG#5 Testing Part 2 Test#2

    Here a snippet where I check if there is water.

    //GET THE WATER DETECT VALUE  WET/DRY 0/1
String GetWaterStatus(){
  String stat;
  int val;
  val = digitalRead(WATER_SENSOR);
  
  if (val == 0){
    stat = "WET";
  }
  if (val == 1){
    stat = "DRY";
  }
//  if ((val != 0) || (val != 1) ){
//    stat = "Water Sensor ERROR";
//  }  
  return stat;
}

    Good Luck with your Fan/humidifier.
    Cheers
    Steve K
     

  • If you have an Arduino and a couple of pieces of hook up wire how about connecting one piece to a digital io with pull-up so it reads high, dangle the other end in the empty reservoir.  The other piece connect to a gnd pin and dangle the other end in the empty reservoir.  Slowly fill the reservoir and when the input pin goes low, water has reached the leads; conversely when it goes high, water level has dropped.  By varying the heights of the leads, and maybe using a 3rd input you could measure high/low levels.  I’ve not tried this by the way and I’m not sure it will work if the reservoir contains water from the dehumidifying process as thst maybe too clean to conduct.

  • in reply to Andrew J
    Andrew J said:
    I’ve not tried this by the way and I’m not sure it will work if the reservoir contains water from the dehumidifying process as thst maybe too clean to conduct.

    Looks like it's a humidifier so the reservoir will likely contain tap water and empty as time goes on.

  • Is there actually anything to burn out ? What is the mechanism being used to humidify ? 

    A float switch (get creative with that wine bottle cork - screw top ? darn !) or perhaps ultrasonic sensor if you want more detail for water usage over time.

  • in reply to beacon_dave
    beacon_dave said:
    Is there actually anything to burn out ?

    However these humidifier units work I suspect the act of water being in contact with them / flowing through them help to keep them cool, since they heat water and shoot it through an exit hole.  I wouldn't trust leaving it running without water.

    beacon_dave said:
    What is the mechanism being used to humidify ? 

    I don't really want to take it apart to identify how it works.


    beacon_dave said:
    A float switch (get creative with that wine bottle cork - screw top ? darn !)

    The hole at the top's relatively small but perhaps there'd be something to that Slight smile

  • in reply to beacon_dave
    beacon_dave said:
    Looks like it's a humidifier so the reservoir will likely contain tap water and empty as time goes on.

    That's correct.

  • in reply to skruglewicz

    Thanks, this looks suitable - I was concerned about the contacts corroding with the water / over time though, have you experienced that at all?

  • in reply to cstanton

    I wouldn't have expected a steam based humidifier to be USB/battery powered.

    Some of the evaporative ones just blow air through a wicking filter or use ultrasonics or an impeller to create a mist that gets blown out by the fan.

  • in reply to cstanton

    The principle still works though, right.  I know this approach is similar to the 'paperclip' approach you've tried but instead of using ADC conversions, you can treat it like an on/off switch.  Essentially, whilst the pin is LOW, there's water there and it doesn't matter if the humidifier is generating noise - unless of course that is peaking between TTL HIGH / LOW ranges!  You might then be looking at something like a Hall Sensor or a dedicated float sensor, like Dave suggests, but you're back to ordering parts if you don't have one on hand.  I still think you're on the right track with leads dipped into the water.