The latest temperature measurements of the biomeiler have had strange variations. The high temperatures were not so high that I couldn’t believe them, but they were higher than I expected. The rate of temperature change, however, was fast enough to trigger my suspicion.
The thermocouple I was using for the reference junction had a plug block that was getting too wiggly for my comfort. I opened it up and found that the wires were twisted across each other. As a test, I checked the reading of the thermocouple with the wires touching and separated and found it greatly affected the reading. I solved the problem by filling the plug block with hot glue to prevent the wires from twisting into contact.
My last effort to simplify the process of taking measurements was a good improvement, but it has still been too fiddly to get all the leads arranged and clipped properly and to keep the alligator clips from sliding off of the smooth, narrow leads of the thermocouples. It is getting colder and taking the measurements while wearing only thin gloves is unpleasant. As a result, my data collection has been skewed in favor of warmer days, rather than being truly representative.
Behold! My new creation.
I purchased two female plugs and wired them together by the negative terminals. The two positive terminals are fitted with ring connectors to provide good purchase for the teeth of the alligator clips. With effort, I might have been able to put more solder on the connectors, but they seem sufficiently secure. Now, all that is necessary for taking measurements is to plug and unplug the twelve thermocouples in the biomeiler and air vent. The reference junction and voltmeter leads can stay connected the whole time. It should be possible to handle the plugs with decent gloves on.
I tested the device (which needs a cool name) by putting both thermocouples in an ice bath and also by leaving one at room temperature. Next, I switched them and took the same sets of measurements. Everything matched. So, tonight, after doing the chicken chores, I will give it a try. It will be nice to wear decent gloves while I take measurements.
