MAX6675 Thermocouple breakout board (TC-6675)

In order to improve and verify the performance of my Reprap Mendel extruder I decided to build a system based on a K-Type thermocouple. I ordered some samples of a MAX6675 from Maxim Integrated Products. I decided to use this chip over the Analog Devices AD595 out of curiosity as it was new to me and due to the 12-bit digital output. Although plenty of breakout boards already exist for this product I decided to design my own based around this PCB-mount thermocouple connector. I like the idea of being able to simply unplug a thermocouple and quickly plug another one in so the use of a standard miniature socket sounds like a pretty good idea to me. It makes switching between probes a breeze and allows me to use cheap thermocouple probes from Maplin

I haven’t tested this board yet so I’ll have to update the post later after I’ve had a chance to play with some ferric chloride.

Having stood back from the design for about 3 seconds it occurs to me that I should probably combine this with my ATTINY45 USB Key project to make a standalone Thermocouple to USB converter, but who has the time 🙂 .

All files are Creative Commons Attribution-Share Alike 2.0
TC-6675, Schematic (PDF)
Eagle Library (MAX6675ISA+ and RS#3817564)
TC-6675 Schematic (EAGLE)
TC-6675 PCB layout (EAGLE)

8 Replies to “MAX6675 Thermocouple breakout board (TC-6675)”

  1. Liking your work. I’m sailing a very similar course to yours, I’ve just posted an arduino mega shield for the RepRap/Mendel and a thermocouple board was next on my list! Thanks for covering the ground for me!



  2. Hi, is the large blue area the ground plane? I am just curious as I am designing a thermostat and I read that a large ground plane helps with accuracy in temp reading. Thank you and excellent post!

  3. Yep, thats the ground plane and it’s there for that exact reason. The overall accuracy is around ±4°C and can have a couple of degrees of noise.

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