Calibrating an Analog pH Sensor (with Linear Algebra)
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- čas přidán 6. 09. 2024
- DFRobot Analog pH Sensor is compatible with both Arduino and Raspberry Pi. Our friend DavyBot gives you a general overview of linear functions and interpolation in this video. Plus he will show you how to write custom code to use this sensor on an unsupported platform (Espruino).
Davy's CZcams channel: / @davybot
DFRobot Analog pH Sensor: www.dfrobot.co...
Arduino Library: github.com/DFR...
Python Library: github.com/DFR...
DFRobot ADC Converter: www.dfrobot.co...
Espruino IDE: www.espruino.c...
It's a little misleading to call this linear algebra, since that suggests matrix methods, transforms, and other actual linear algebra methods.
What you've built is a 'calibration curve' (sometimes called a 'standard curve').
This is very useful in chemistry but you must obey some rules.
1) You have zero certainty when extrapolating a reading beyond the two points you measured (above the highest and below the lowers). The reason being that you cannot guarantee the approximation you've made (the linear function is an approximation of some unknown 'perfect' pH v. voltage function) is still valid in those regions. You did mention this but it should have a more prominent focus since this is a video on calibration.
2) Sensitivity of the device is usually not the same at all points along this line. The probe might be overwhelmed at high very pH or it might not be able to pickup an accurate signal at very low pH. It's important to know the limits of the device so that you avoid calibrating (and therefore, measuring) in those regions. Some of these regions may also have a nonlinear response and your linear approximation will definitely be invalid.
There are some other important details but these two should always be mentioned when discussing probes and chemical measurements.
Such a good video. Thx man!
nice information, is there a non-linear analog to linear out function? 🤔 thank you. 👌
sorry, i am working with stm to read sesor PH and i have the following problem!
STM has VREF + (3.3V) while arduino with VREF+ (5V) so I cannot use the arduino formula to apply to STM. Do you have a suggestion for me?
Hi, maybe you could do the calibration job on a non-Arduino MCU with VREF+(3.3V) referring to this video. Otherwise, there is a 5V pH Meter Pro for you which you can use the Arduino formula perfectly: www.dfrobot.com/product-1110.html?tracking=5b603d54411d5
Hello, would this sensor be appropriate for long-term usage such as continuous monitoring for water quality systems, or just for short-term dipping?
Can I use this to measure the ph value of soil
I have the library of dissolved oxygen sensors don't let me ask