Arduino Forum

Using Arduino => General Electronics => Topic started by: Delta_G on Jan 17, 2015, 05:39 pm

Title: Water on the Floor Detector
Post by: Delta_G on Jan 17, 2015, 05:39 pm
Can anyone recommend a good sensor for detecting water on the floor?  I need to be able to shut a pump down if a leak is detected so I don't flood my house.  Bonus points if it is something that can easily DIY.  I was thinking of using two wires closely spaced and checking for continuity, but I don't know how reliable that would be.   
Title: Re: Water on the Floor Detector
Post by: larryd on Jan 17, 2015, 05:52 pm
For the sensor, two bare wires placed in different holes in corrugated cardboard.
Title: Re: Water on the Floor Detector
Post by: pwillard on Jan 17, 2015, 06:11 pm
This makes a good "water on the floor" sensor.

leaf wetness sensor (http://www.hobby-boards.com/store/products.php?product=Leaf-Wetness-Sensor)
Title: Re: Water on the Floor Detector
Post by: Boardburner2 on Jan 17, 2015, 06:34 pm
I used a 5 kit from maplins as a leak detector under my sink.
Was a kit i think
Title: Re: Water on the Floor Detector
Post by: jremington on Jan 17, 2015, 06:54 pm
I use a piece of PCB with fingers, like this one: http://www.circuitstew.com/pcbs/water_alarm.html
An Arduino is certainly overkill as you need only about four parts to make a very reliable leak detector. Google "water leak alarm circuit" for thousands of possibilities.
Title: Re: Water on the Floor Detector
Post by: Delta_G on Jan 17, 2015, 06:57 pm
Thanks for the suggestions.  So it doesn't look too hard. 


I use a piece of PCB with fingers, like this one: http://www.circuitstew.com/pcbs/water_alarm.html
An Arduino is certainly overkill as you need only about four parts to make a very reliable leak detector. Google "water leak alarm circuit" for thousands of possibilities.
The arduino is already involved.  It's the thing deciding when to turn the pump on and off in the first place. 
Title: Re: Water on the Floor Detector
Post by: MorganS on Jan 17, 2015, 07:26 pm
A float switch is more reliable than wires. The DC current through the wires will corrode them relatively quickly. You may need to build a dam around the pump to get a deep enough puddle for the float switch to float.

Sump pumps and bilge pumps do the opposite. (Turn on when water detected.) Perhaps their float switches are available separately?
Title: Re: Water on the Floor Detector
Post by: larryd on Jan 17, 2015, 07:30 pm
Quote
A float switch is more reliable than wires
Not if the wires are always dry ;)
If it is just for an alarm then you simply replace the cardboard sensor as needed.
Title: Re: Water on the Floor Detector
Post by: raschemmel on Jan 17, 2015, 08:53 pm
I've used this ic before. It works great.

LM1830 FLUID DETECTOR IC (http://www.engineering.uiowa.edu/sites/default/files/ees/files/NI/pdfs/00/57/DS005700.pdf)
Title: Re: Water on the Floor Detector
Post by: Coding Badly on Jan 17, 2015, 09:08 pm
I've used this ic before. It works great.
At 5V?

Title: Re: Water on the Floor Detector
Post by: Delta_G on Jan 18, 2015, 02:18 am
A float switch is more reliable than wires. The DC current through the wires will corrode them relatively quickly. You may need to build a dam around the pump to get a deep enough puddle for the float switch to float.

Sump pumps and bilge pumps do the opposite. (Turn on when water detected.) Perhaps their float switches are available separately?
Yeah, it's just an alarm.  I have a float valve at the top of the tank that physically stops the flow to prevent overflow, but I don't have anything to detect water on the floor starting to puddle if I had let's say a leak in a hose like the one I had this morning.  Even if it has a 50% chance of working, that's 50% better chance that I don't do this again.  I like those odds. 

Title: Re: Water on the Floor Detector
Post by: raschemmel on Jan 18, 2015, 03:23 am
Quote
I've used this ic before. It works great.
Quote
At 5V?   
No.  It won't work at 5V. It requires 16V minimum.
Title: Re: Water on the Floor Detector
Post by: Delta_G on Jan 18, 2015, 06:29 am
I've got 5V and 12V DC and 120VAC, but no 16V.
Title: Re: Water on the Floor Detector
Post by: Paul__B on Jan 18, 2015, 07:59 am
For the sensor, two bare wires placed in different holes in corrugated cardboard.
(http://forum.arduino.cc/index.php?action=dlattach;topic=293052.0;attach=110066;image)
Plausible circuit - almost - but why do people always dash off something straight from "Electronics for beginners" rather than thinking about the design?

Having one sensor terminal connected to 5V is just asking for corrosion to occur, and for the device to fail if either or both sensor wires are more strongly conducting to ground (such as perhaps - a floor?) than to each other.  At least the 1k resistor prevents such a short to ground from affecting the power supply itself.

The more appropriate circuit would have the sensor between the input terminal (of the Arduino directly would be OK if isolated by a 47k resistor) and ground with a "shunt" resistor to 5V of 47k or so.  In fact, that "5V" could be provided by another Arduino pin which was only pulsed HIGH occasionally when necessary to make a reading, and the sensor connected only via a capacitor (maybe 1µF, ceramic or plastic) to remove any DC current which could cause electrolysis.

D-question-mark?
Title: Re: Water on the Floor Detector
Post by: larryd on Jan 18, 2015, 09:13 am
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dash off
If it's beyond ones  capability they can decide to do otherwise.
This is under General Electronics.
I thought this was a place for idea exchange.

I have used this cct. for years.
I have experienced zero corrosion as this is a dry sensor (until there is an alarm, then you exchange the cardboard). There is no electrolysis.
The cct. power supply is from a wallwart isolated from earth.
The cct. is designed like this to support long cable lengths (some of mine are 30+ feet).
I have used multiple sensors attached in parallel to the same input point.

Quote
The more appropriate circuit . . .
Offer what you want.

I didn't realize this was a contest.
Title: Re: Water on the Floor Detector
Post by: Paul__B on Jan 18, 2015, 12:55 pm
I thought this was a place for idea exchange.
...
I didn't realise this was a contest.
Well, if you see it that way, that is rather unfortunate.  Sad, really.

There are varying expectations of engineering - "just enough" to get the job done, or robust.

I am sure your circuit works - given the constraints of your particular application.  But the danger is that it may then be assumed to be applicable in the more general sense, for water level indication - a not uncommon question (http://forum.arduino.cc/index.php?topic=289393.msg2024880#msg2024880) here.
Title: Re: Water on the Floor Detector
Post by: dave-in-nj on Jan 18, 2015, 04:34 pm
http://www.homesecuritystore.com/extra-floodstop-sensor-pad

simple board with parallel serpentine etching.

looks nearly identical to the wet leaf sensor
Title: Re: Water on the Floor Detector
Post by: larryd on Jan 18, 2015, 04:59 pm
Quote
Sad, really.
Issues with life, or just everything in general.
Quote
given the constraints of your particular application.
OP is looking at detecting water on the floor in his home not a art gallery.
Quote
I am sure your circuit works
I does, has been since 2005.

Aapologies to the OP
Title: Re: Water on the Floor Detector
Post by: raschemmel on Jan 18, 2015, 07:52 pm
I have 30 yrs experience with electronics and both of the circuits suggested are equally simple and appropriate for a beginner and both should be reliable. If I were in the OP's shows shoes and couldn't use (or obtain) the fluid detector ic I would use either of the circuits. (whichever seems more convenient to fabricate).  My sensor leads for the fluid detector ic were two wires inside of plastic straws taped together  flat on the floor with the bare wires extending 1" from the end of the straws and taped 1/4" apart to a thin piece of stiff plastic (like a piece of credit card cut off of an expired credit card). It worked perfectly . I tested it by dipping the bare ends in a glass of tap water. I really don't see the need to be overly critical of the design for this application.
Title: Re: Water on the Floor Detector
Post by: dave-in-nj on Jan 19, 2015, 05:39 am
Aapologies to the OP
Ras...  
Aapologies  - Middle French or Late Latin; Middle French apologie, from Late Latin apologia, from Greek, from apo- + logos speech -- more at legend
First Known Use: 1533
this one is from the middle french, but we expect to read it in English.



Quote
Quote from: raschemmel  (http://"http://forum.arduino.cc/index.php?msg=2048619")Sun Jan 18 2015 

...If I were in the OP's shows...
then you would be an actor.......


Title: Re: Water on the Floor Detector
Post by: dave-in-nj on Jan 19, 2015, 05:41 am
just to touch on the technology.

a float switch often has to 'lift' about an inch before tripping.

a circuit on the concrete, be it in cardboard, in straws, or a PCB, only needs the presence of water.

lots of good ideas in this thread.  I think the OP cannot go wrong with any of them.
Title: Re: Water on the Floor Detector
Post by: dave-in-nj on Jan 19, 2015, 05:43 am
just to touch on the technology.

a float switch often has to 'lift' about an inch before tripping.

a circuit on the concrete, be it in cardboard, in straws, or a PCB, only needs the presence of water.

lots of good ideas in this thread.  I think the OP cannot go wrong with any of them.
Ras...  
Aapologies  - Middle French or Late Latin; Middle French apologie, from Late Latin apologia, from Greek, from apo- + logos speech -- more at legend
First Known Use: 1533
this one is from the middle french, but we expect to read it in English.



then you would be an actor.......



I probably should not be commenting on grammar and spelling as I offer more fodder than most when it comes to offering mistakes for others to find.

Title: Re: Water on the Floor Detector
Post by: raschemmel on Jan 19, 2015, 04:22 pm
Quote
then you would be an actor.......
ha, ha, ha, very funny.... ;D