Interfacing TDS/EC Tester/Meter

Projects General Guidance
1

I am working on a project regarding the water pollution and I am using a TDS Meter to indicate the Total Dissolved Solids (TDS) of a solution, i.e. the concentration of dissolved solids in it. Since dissolved ionized solids such as salts and minerals increase the conductivity of a solution, a TDS meter measures the conductivity of the solution and estimates the TDS from that. Dissolved organic solids such as sugar and microscopic solid particles such as colloids, do not significantly affect the conductivity of a solution so a TDS meter does not include them in its reading.

So I bought a TDS Meter from ebay and it’s a cheap one

I tried to hack on it in order to get the output readings and interface them to an Arduino board. However, I couldn’t locate the output readings because I faced some problems with this IC which was completely new for me. I couldn’t identify either its model or its number

This are the front and the back pictures of TDS meter after being hacked . However, I couldn't find the output of the IC so can anyone help regarding this issue? and thanks.

So do you guys have any suggestions of what I am supposed to do in order to locate the place of the output and interface it with the Arduino board ?

Thanks in advance.

2

The output may not be available, you may have to interupt the signals to the lcd to get what you need, then just "push" the buttons with the arduino to get the info

3

Or figure out how it does it and do it yourself

4

I'm trying to check those lines under push-bottoms and take readings for clear water and salty water

I've already found http://www.octiva.net/projects/ppm/ but I prefer to hack that meter and take the reading directly.

5

Now when you say directly you mean the final value or the raw value from the sensor? Maybe the value from the sensot would be more accessible

6

unfortunately all control lines of the LCD give me 3V (which is the VCC) whatever the meter is in water or not :frowning:

now I'm trying to take the I/P of the sensor then search about a relation to give me the exact TDS

7

KG77:
So I bought a TDS Meter from ebay and it’s a cheap one

Have you confirmed that the meter does actually work, before trying to reverse engineer it?

8

PeterH:

KG77:
So I bought a TDS Meter from ebay and it’s a cheap one

Have you confirmed that the meter does actually work, before trying to reverse engineer it?

Yes, it's working perfectly

9

Even if you found which traces the output was on, how would you get that info? And the actual number is in the processor, the only info outside it is the i/o to the lcd