limjix:
I have some questions which I hope you will be able to help me with:
I am going to order a pH sensor on ebay, which comes with a BNC connector. I am perplexed at this BNC thing. I was wondering why bother using a BNC connector when I can just use the individual wires in the coil to connect them to the inputs on an arduino?
Is there any advantage of using a BNC connector and how should I harness it?Any other input or ideas of how I need to improve this further?
Thank you so much!
If it's going to be used more than a few times, are there any issues relating to the sensor life? For example if it's possible for it to be damaged or wear out or go out of calibration, you'll need to replace it. Having a nice clean reliable BNC connector will be much better for that than having to disconnect cables hardwired to the Arduino pins.
Would you consider adding a display of the current and target PH values, and a knob/buttons to give control of the target?
Your proposed linear algorithm relies on the zero point of the servo exactly matching the zero flow condition. If it is off even slightly, the servo will shut the flow off above or below your target PH. I suggest using a PID or similar algorithm to control the servo. When set up correctly, this will ensure that the PH settles at the target regardless of any slight variations in the servo/valve mechanism.