Hi everyone, I'm working on a project and I'm in the process of setting up a ph sensor. The problem im having is my ph monitor/pumprelay controller is having some sort of ground loop issue. For my powersupplys I use a 5v Samsung wall charger running to a ams117 3.3 volt regulator for an esp8266 and the LCD screen. I use a 12v 700ma dc wall adapter to power the arduino and the ph sensor controller. The ground from both of these power supplies are connected at the arduino. Now when my ph meter is in the water without any pumps or current leakage I get a perfect reading. But when I set the pumps or anything electrical in the water it moves up by about exactly 1.0 from the ground loop. I am looking at building a dc -dc galvanic isolator to stop this issue but I'm not sure where to place it and how many I need. The ph sensors works on the arduino analog input. Can someone give me some advice. Maybe they even make an breakout board with an isolator to make this easier. Please help me thankyou.
But when I set the pumps or anything electrical in the water it moves up by about exactly 1.0 from the ground loop.
If there is leakage from the pumps or "anything electrical" into the water, you'll have to remedy that. Obviously the sensor needs a contact with the water and any other current through the water from any other source might mess-up the reading.
I doubt that grounding is the problem, but is the Arduino power supply earth-grounded? The Arduino ground doesn't have to be earth-grounded so it can be isolated everything else. ....Until you stick it in the water, and then there may be a path to ground or some other voltage, etc. If the USB is connected to a computer, it can get earth-grounded through the computer.
Maybe you can pump a sample of the water into a separate little tank/bucket to check the PH? That could be completely isolated.
But when I set the pumps or anything electrical in the water it moves up by about exactly 1.0 from the ground loop.
I suppose you could subtract 1.0 from the reading...
The arduino power supply is not earth grounded. However if I earth ground the ph bnc ground then them problem is 50% better. Everything I've been reading from Googling arduino ph ground loop, I've been readying there needs to be a dc-dc galvanic isolator for this to work. I'm not sure what to do here. I've tried a lot of different grounding configuration none make any difference besides putting an earth ground to the ph sensor ground. I would like to try the galvanic isolation but I don't know the correct way to do that?
Just now, so far the solution I found is to drop an earth ground into the water itself with the ph sensor and everything is fine. Is it okay to run a 10kohm resistor to the earth ground on the arduino?