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Convert GS-WDS07 433Mhz Door sensor to Water sensor


Further to the previous post, I opened a new post.

I have this GS-WDS07 433Mhz Door sensor and i want to connect instead the REED Switch a water leak sensor (2 pins only with cable).
So I dismantled the REED and measured its resistance and it came out at about 50 ohms, I tried to put a similar resistor but it immediately turned on the sensor, I also connected only the wires instead of the REED and tested with a glass of water but it did not activate the sensor. I only measured the resistance of the sensor and it gave 1.5M ohms and put it in a glass of water (obviously disassembled and not connected to the RF module) it gave me the same 1.5M ohms value sometimes cut to 2.5M ohms.

any idea how to make its work ?

If when into the glass of water you are around 1.5-2.5Mohms you should add a transistor in your circuit.

Nevertheless could you explain the goal of using GS-WDS07 instead of off the shelves 433mhz leakage sensors?

I ordered a lot of such door sensors and I stayed 5 and thought of turning them into water sensors, I didn’t think it was that complicated.
Why are you going to add a transistor? What exactly would he do?

The transistor will act as an amplifier of the current detected when water goes through your sensor, it will let pass more current compared to the water sensor itself.

In my point of view for a security related device like a water detector I would go for off the shelves, just my thoughts.

There is something I do not understand, REED SWITCH is just a standard two pins switch, the water sensor I have is two-pin with two wires that once the water touches both legs is short-formed.
My question is why can it be used this way? Doesn’t water shorten?

I would love some circuit diagram for the transistor if you can of course

Your sensor is returning a too high impedance to replace the reed switch as it is.
1500 000 ohms cannot be handled electronically like 50 ohms.

any chance to get more info how to add transistor ?

i measure only the water and get 1.5M ohm and only the sensor is 40-50 ohm

Sorry but I don’t get it, could you be more accurate please:
-Water sensor impedance without water
-water sensor impedance with water
-reed switch impedance when close
-reed switch impedance when far

here is the reslt :

Water sensor impedance without water


water sensor impedance with water


reed switch impedance when close


and when reed switch impedance when far there is no measure (open circut) .

also the volt on 2 leg is

Hope now its OK…

You should measure the impedance between the blue and the orange I think?

ok, that’s clear

ok, seems like a wire contact

I did it, its doubled the result and its about 40-45 ohms

so any idea why its not working ?

Yes, to make it works you should build a circuit that generate an open switch when you have water and a close switch when you don’t have water.
You should better ask on a forum dedicated to electronics, you will have better chances to find support.