everything works technically and im getting realistic values from the sensor via ESPhome.
i let the project rest for a few weeks and when i took it up again my measured values are all over the place.
[04:44:02][D][sensor:093]: ‘pH Sensor’: Sending state 11.42803 pH with 2 decimals of accuracy
[04:44:22][D][sensor:093]: ‘pH Sensor’: Sending state 11.62944 pH with 2 decimals of accuracy
[04:44:42][D][sensor:093]: ‘pH Sensor’: Sending state 9.49443 pH with 2 decimals of accuracy
[04:45:02][D][sensor:093]: ‘pH Sensor’: Sending state 7.68169 pH with 2 decimals of accuracy
[04:45:22][D][sensor:093]: ‘pH Sensor’: Sending state 9.01104 pH with 2 decimals of accuracy
[04:45:42][D][sensor:093]: ‘pH Sensor’: Sending state 9.85698 pH with 2 decimals of accuracy
[04:46:02][D][sensor:093]: ‘pH Sensor’: Sending state 11.22661 pH with 2 decimals of accuracy
[04:46:22][D][sensor:093]: ‘pH Sensor’: Sending state 9.13189 pH with 2 decimals of accuracy
[04:46:42][D][sensor:093]: ‘pH Sensor’: Sending state 6.51348 pH with 2 decimals of accuracy
[04:47:02][D][sensor:093]: ‘pH Sensor’: Sending state 9.97783 pH with 2 decimals of accuracy
[04:47:22][D][sensor:093]: ‘pH Sensor’: Sending state 10.09868 pH with 2 decimals of accuracy
[04:47:42][D][sensor:093]: ‘pH Sensor’: Sending state 10.09868 pH with 2 decimals of accuracy
[04:48:02][D][sensor:093]: ‘pH Sensor’: Sending state 10.86406 pH with 2 decimals of accuracy
[04:48:22][D][sensor:093]: ‘pH Sensor’: Sending state 9.41387 pH with 2 decimals of accuracy
The PH Scale only goes from 0-14 so this movement up and down over a few minutes is not realistic. there is no change in the water that im measuring.
Do you have an oscilloscope? If so, measure the signal across the potentiometer.
Otherwise, give it a few turns back and forth (you’ll need to recalibrate, of course).
Potentiometers are notorious for carbon buildup, leading to resistance issues. My suggestion would be, once calibrated, put a fixed resistor in place. Otherwise, buy a higher quality pot or use an optical rotary encoder instead.
Interesting, I already ordered a fixed 5v to 3.3v converter because I wanted to exclude another moving variable. There is already a trimpod on daughter board for the probe (right in picture) that is hard to dial in.
Altough I dont think the potentiometer is new enough for that not to happen, ill exchange it with the converter.
i measured the signal voltage at the earliest point on the daughterboard and it jumped quite a bit. so i must have shorted up something on the daughter board.
Luckily i had another one from earlier experiments and although the variance still seems a bit high this looks normal enough now
[09:13:03][D][sensor:093]: ‘pH Sensor’: Sending state 10.09868 pH with 2 decimals of accuracy
[09:13:23][D][sensor:093]: ‘pH Sensor’: Sending state 9.77642 pH with 2 decimals of accuracy
[09:13:43][D][sensor:093]: ‘pH Sensor’: Sending state 10.05840 pH with 2 decimals of accuracy
[09:14:03][D][sensor:093]: ‘pH Sensor’: Sending state 10.05840 pH with 2 decimals of accuracy
[09:14:23][D][sensor:093]: ‘pH Sensor’: Sending state 9.57500 pH with 2 decimals of accuracy
[09:14:43][D][sensor:093]: ‘pH Sensor’: Sending state 9.73613 pH with 2 decimals of accuracy
[09:15:03][D][sensor:093]: ‘pH Sensor’: Sending state 9.81670 pH with 2 decimals of accuracy
[09:15:23][D][sensor:093]: ‘pH Sensor’: Sending state 10.13897 pH with 2 decimals of accuracy
[09:15:43][D][sensor:093]: ‘pH Sensor’: Sending state 9.77642 pH with 2 decimals of accuracy
[09:16:03][D][sensor:093]: ‘pH Sensor’: Sending state 9.73613 pH with 2 decimals of accuracy
