It uses screw terminals to connect the K-type thermocouple, because that wire can’t be soldered – I tried, really hard! Besides, you don’t want to add too many weird amalgamated cold metal junctions in this setup, which is all about the tiny voltage potential between different metals.
The whole thermocouple works nicely, but I goofed a bit on the connector: the screw terminal I got for this plug is slightly too big to fit on there in the intended position:
Yuck … two solutions:
- solder it on anyway, and just ignore that tower-of-pisa effect…
- solder it on the other way, and insert the thermocouple wires from the board side
Here’s how that will look:
Slightly odd, but it’ll work just fine of course.
Note that the back side of this screw terminal has two holes, but they cannot be used to insert wires, because those will end up too high and wouldn’t be held tight by the screws:
I’ll look around for a slimmer form-factor 3.5 mm screw terminal. If I can’t find any, then I’ll plan a board revision – but for now, it’ll have to do.
With a small nod to Mr. Murphy…