Nathan.Rivard
Posts: 37
Joined: Tue Sep 10, 2019 3:28 pm

Looking for a relatively low-cost electrical conductivity sensor that gives the signal in digital output

Mon Oct 07, 2019 6:34 pm

Just as the title says. I am looking for a low cost electrical conductivity sensor that gives the output in a digital signal, but if that is impossible I can make do with an analog output. I have looked around and not found much in terms of affordability and would just like a little assistance.

btidey
Posts: 1636
Joined: Sun Feb 17, 2013 6:51 pm

Re: Looking for a relatively low-cost electrical conductivity sensor that gives the signal in digital output

Tue Oct 08, 2019 8:17 am

You need to give a bit more info to get some suggestions.

What type of material are you trying to measure; liquid, solid?

What range of conductivity are you trying to measure?

What accuracy are you trying to achieve?

Conductivity is normally measured by sensing the current flow across a known geometry of substance with an applied voltage. In some cases, particularly liquids, it is desirable to use an AC voltage to prevent electrode effects.

Nathan.Rivard
Posts: 37
Joined: Tue Sep 10, 2019 3:28 pm

Re: Looking for a relatively low-cost electrical conductivity sensor that gives the signal in digital output

Tue Oct 08, 2019 1:17 pm

btidey wrote:
Tue Oct 08, 2019 8:17 am
You need to give a bit more info to get some suggestions.

What type of material are you trying to measure; liquid, solid?

What range of conductivity are you trying to measure?

What accuracy are you trying to achieve?

Conductivity is normally measured by sensing the current flow across a known geometry of substance with an applied voltage. In some cases, particularly liquids, it is desirable to use an AC voltage to prevent electrode effects.
I am measuring through a liquid, in this case its water. I'm looking for a relatively high range as I will have dissolved solids within the liquid. The accuracy I am trying to achieve is ±.01mS.

Crowbot
Posts: 24
Joined: Sat Jul 13, 2019 2:03 pm
Location: NYC

Re: Looking for a relatively low-cost electrical conductivity sensor that gives the signal in digital output

Wed Oct 09, 2019 5:38 pm

I found this on Amazon. Look for "Arduino water sensor". I believe it has a digital output but would need to be calibrated to the specific fluid.
arduino water sensor.jpg
arduino water sensor.jpg (55.95 KiB) Viewed 875 times

pcmanbob
Posts: 9456
Joined: Fri May 31, 2013 9:28 pm
Location: Mansfield UK

Re: Looking for a relatively low-cost electrical conductivity sensor that gives the signal in digital output

Wed Oct 09, 2019 5:58 pm

Crowbot wrote:
Wed Oct 09, 2019 5:38 pm
I found this on Amazon. Look for "Arduino water sensor". I believe it has a digital output but would need to be calibrated to the specific fluid.
I think you will find it has an analogue output, as more water lands on the sensor strips or the probe in lowered deeper in to water the the more the transistor will be turn on, resulting in a higher voltage on terminal S, until at full conductivity S = +
We want information… information… information........................no information no help
The use of crystal balls & mind reading are not supported

PhatFil
Posts: 1680
Joined: Thu Apr 13, 2017 3:55 pm
Location: Oxford UK

Re: Looking for a relatively low-cost electrical conductivity sensor that gives the signal in digital output

Wed Oct 09, 2019 6:13 pm

Cheapest easiest EC meter i know of is built into the £10-£15 Miaflora plant sensor from Xiaomi which if not paired with its suggested app (as this will apply incompatible updates) can be queried via Bluetooth BLE by your Pi as detailed in these 2 older projects
*As far as i am aware all devices are shipped with an old firmware and rely on the app to update.. But its always a punt when buying equipment with unintended use intentions

https://zsiti.eu/xiaomi-mijia-hygrother ... pberry-pi/

https://github.com/ThomDietrich/miflora-mqtt-daemon

If you use node red there is a contrib node you can add from the pallette to communicate/query the sensors all you need is the b/tooth mac addy of the device which you can easily deduce using hcitool lescan as explained in the above links

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