Better thermocouple sample readings
Posted: Mon Jun 11, 2012 5:02 pm
I've attempted to find this answer out myself through the wiki, but am still having a hard time figuring it out. Any assistance would be helpful.
I measure the temperature inside my cellar fridge by having the thermocouple inside a 500ml water bottle full of Starsan sanitizer. For whatever reason, the temperature measurements seem to swing about 4-5 degrees up and down in any given 5-10 seconds. I can't imagine that the water flowing over the tip (which is roughly in the middle of the water, not on the edge) would actually fluctuate that much, but maybe that is the case. Or, maybe it's due to the 30 ft extension of 24 AWG CL2 shielded wire I added between the thermoprobe and the BCS.
What I'm looking for is a way to get an "average" reading over, say 15-20 seconds, rather than a constant reading. That way the fridge doesn't constantly kick on and off and waste electricity based on a split second low reading. Is this possible? I've read the Output PWM Control page, but am still unclear about the exact way to go about this. I've changed the hysteresis to 4 degrees to help account for some of the erratic swing, but I'd rather turn that down to 2 or 3 degrees and adjust other parameters to get a more "average" reading.
I would also like it to be that when the fridge does turn on, it will stay on for a minimum amount of time (say, 3 minutes), regardless of the temperature swing.
I measure the temperature inside my cellar fridge by having the thermocouple inside a 500ml water bottle full of Starsan sanitizer. For whatever reason, the temperature measurements seem to swing about 4-5 degrees up and down in any given 5-10 seconds. I can't imagine that the water flowing over the tip (which is roughly in the middle of the water, not on the edge) would actually fluctuate that much, but maybe that is the case. Or, maybe it's due to the 30 ft extension of 24 AWG CL2 shielded wire I added between the thermoprobe and the BCS.
What I'm looking for is a way to get an "average" reading over, say 15-20 seconds, rather than a constant reading. That way the fridge doesn't constantly kick on and off and waste electricity based on a split second low reading. Is this possible? I've read the Output PWM Control page, but am still unclear about the exact way to go about this. I've changed the hysteresis to 4 degrees to help account for some of the erratic swing, but I'd rather turn that down to 2 or 3 degrees and adjust other parameters to get a more "average" reading.
I would also like it to be that when the fridge does turn on, it will stay on for a minimum amount of time (say, 3 minutes), regardless of the temperature swing.