Timeline for Range of Offset Value in pH sensor module?
Current License: CC BY-SA 3.0
11 events
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| Apr 13, 2017 at 12:50 | history | edited | Community Bot |
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| May 20, 2016 at 12:23 | comment | added | Shiva Teja | After doing a lot of Calibrations, I used offset value as -4.0, For Solution of pH 7, its showing the value same as 7.0.. for pH solution of 4.0, its showing 5.2(4.0+1.2)... for pH solution 10, its showing 8.8(10-1.2).. To get correct values for pH solutions of 4 and 10, What I need to do? | |
| May 20, 2016 at 12:09 | comment | added | Code Gorilla | Something you may also want to consider is what happens if one reading is massively different to the other 5 readings. It probably indicates a sensor fault for that reading, but it will move your answer towards pH=1. I don't think you should be dividing by 1024. This division will loose some precision in your reading and therefore it will make you calibration table less accurate. | |
| May 20, 2016 at 12:04 | comment | added | Code Gorilla | I don't think you mean -3.5v, because the voltage range you are measuring is 0-5v. At the moment all you know is when the variable phValue = 10.5 then the pH of the liquid is 7.0. Like st2000 says you now need to pad out your calibration table what does pH 1 make your device read? pH = 2 ? etc. Then you will get a table that says when the sensor reads 3.9 it means pH = 1, when it read 5.2 it means pH=2, when it reads 4.9 it means about pH 1.8. | |
| May 20, 2016 at 9:50 | vote | accept | Shiva Teja | ||
| May 20, 2016 at 9:50 | |||||
| May 19, 2016 at 21:47 | review | First posts | |||
| May 20, 2016 at 6:41 | |||||
| May 19, 2016 at 13:58 | answer | added | st2000 | timeline score: 1 | |
| May 19, 2016 at 13:42 | comment | added | st2000 | It is doubtful any ADC / sensor combination is exactly linear, of the correct magnitude, slope and w/o noise. How precise / accurate your application needs to be should dictate your efforts. My next steps would be to plot know acid and bases to resolve these questions. | |
| May 19, 2016 at 12:25 | comment | added | Shiva Teja | I tested it for water of pH 7.0. It's showing a value of 10.5 units. So, I considered -3.5v as an offset value..While considering offset value as -3.5v, I got a doubt that is there any limited range for an offset value to consider | |
| May 19, 2016 at 12:13 | comment | added | Code Gorilla | I think you would need to test it by testing known value solutions with your sensor. It is probably going to be different between different instances of the sensor so each will need calibrating in this way. | |
| May 19, 2016 at 12:07 | history | asked | Shiva Teja | CC BY-SA 3.0 |