thanks for the feedback @amanfredi and @BDub
measure the resistance of your 22k resistor if you didn’t already — its actually 20.8k when i measure. i updated the formula to R = (1 / ((4095 / (double) aval) - 1)) * (double) 20800;
measure the resistance of your probe from A4 to GND and see if it’s actually close to 167,635 Ohms – confirmed
Also measure the resistance of the probe from the ends of the plug connector – those connections look pretty loose from the photo. — yep, i soldered them since photographing, and the resistance measure is much more stable
measure the voltage between 3.3V* and GND – 3.26
measure the voltage across the 22k resistor, it should be (3617 / 4096) 3.3 = 2.91479V if your analogRead value is accurate and 3.3V is supplying the correct voltage – yes, its 2.94
Still seeing some fluctuations…here is the thermistor in 50degree water
Analog Reading:3727
Resistance:212682.07
Temperature:74
Analog Reading:3733
Resistance:216555.25
Temperature:73
Analog Reading:3733
Resistance:216555.25
Temperature:73