Hi,
i want to understand what logic is used behind the water leak detection using sensing cable (called as 'water rope sensor'). How the two wires are used to detect the water leak ?
Could you please help me understand the logic behind this ?
reference: http://gemwel.com/product/monnit-wireless-water-rope-sensor-commercial-aa-battery-powered/

 

It is detecting the resistance between the 2 wires reducing via the conductive liquid that they are placed in.

 

It is detecting the resistance between the 2 wires reducing via the conductive liquid that they are placed in.

Won't that mean that the electricity is flowing through the water? Is it not dangerous?

 

Hi Dendad,
thank you so much for valuable answer.
I am thinking will length of the wire and moisture/dust cause any impact on measurement?
Can it be done with 5V supply for the rope wire >4m ?

 

hi raja,
The two core wire rope would be one 'arm' in a Wheatstone bridge, the bridge would drive a comparator and alarm.

Could you post more details of the application.

BTW: Using a voltage of 5V is NOT dangerous.

E

 

Hi,
I am interested to do the same type of leak detection to get more idea, i have tried to use water sensor to detect rain/water drops in single point. Now i like to use water rope sensor to detect liquid or water falling inside my computer room.
i am interested on doing electronics hobby projects, so started playing with that. I have strong knowledge in firmware but lacking in hardware side. So, need help/suggestion from experienced developer/designer like you.
I need some reference or details to design this myself.

 

Just for interest, a one off moisture detector that I saw in an article, used in a homemade sub, was a peg with a couple of contacts on it and they were held apart with a soluble tablet, like an Aspirin or something like that, and placed in the lowest part of the container. When it dissolved, the 2 contacts met and completed the circuit and so that switch closure was used to raise an alarm.

 

hi raji,
What is the area you want to cover in checking for leaks in your room.
Is it walls, ceiling or floors?
E

 

Hi Eric,
It is floors mainly

 

hi,
From what you are saying, you want a water detection method that is resettable which can be used over period of time, not just a one time leak detector.??
It should be possible to make a leak sensor using tinned copper wires fixed to a backing insulator, what is the total leak detect area ?
E

 

Hi,
i want to understand what logic is used behind the water leak detection using sensing cable (called as 'water rope sensor'). How the two wires are used to detect the water leak ?
Could you please help me understand the logic behind this ?
reference: http://gemwel.com/product/monnit-wireless-water-rope-sensor-commercial-aa-battery-powered/

These devices send a small electrical signal through 2 conductors, at the end of the "rope" it uses another resistor to ground and a signal to an analog to digital converter.

Between the impedance of the rope(r1) and the impedance of the resistor(r2) you have a voltage splitter. If it gets wet than the two wires short and decreases the impedance thus changing voltages. This change is registered by the ADC and you can determine where on the rope a short has occured