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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?

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  • cstanton said:
    I couldn't wait for looking up too much detail or ordering parts from an online store.

    Guys, I think this is the key line: what can be done with what is to hand rather than buying sensors or such.  Obviously, we don't know what Chris has to hand but I'm assuming for this experiment, little more than resistors, capacitors, wires, battery, Arduino and the like.  I guess it's ok to assume standard household stuff as well: perhaps a cork, paperclip(!), plastic milk bottle cap, wire coat hanger etc.  Simple stuff.  It's an interesting problem.  So suggestions that don't require logging on to a parts store!

    "....detect how much water is left" is a different proposition to "...is it about to get empty" as it implies either steady readings as the water level drops, or an indication of the water level at pre-specified points, e.g. 3/4, 1/2, 1/4, 1/8 full.

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  • cstanton said:
    I couldn't wait for looking up too much detail or ordering parts from an online store.

    Guys, I think this is the key line: what can be done with what is to hand rather than buying sensors or such.  Obviously, we don't know what Chris has to hand but I'm assuming for this experiment, little more than resistors, capacitors, wires, battery, Arduino and the like.  I guess it's ok to assume standard household stuff as well: perhaps a cork, paperclip(!), plastic milk bottle cap, wire coat hanger etc.  Simple stuff.  It's an interesting problem.  So suggestions that don't require logging on to a parts store!

    "....detect how much water is left" is a different proposition to "...is it about to get empty" as it implies either steady readings as the water level drops, or an indication of the water level at pre-specified points, e.g. 3/4, 1/2, 1/4, 1/8 full.

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