Custom 4-input thermocouple thermometer, a design/build log

Some guy I know requested that I build a four input thermocouple thermometer for benching use. This is the log of that process.

Thermocouples require amplification before most things can get a temperature out of them, the MAX31855 chip does that as well as other thermocouple housekeeping. It outputs in SPI (more or less) that a microcontroller can read.
I built a breadboard two input flavor for myself to use for PSU intake/exhaust temperature testing a while ago, I need to make myself a PCB version for that as well as the four input flavor for benching use.

I'm just starting the process now, and will be using this thread to keep notes for myself and others.
Input and comments are always welcome

awesome, can't wait to see how it turns out. I bet if you can make a great 4-input meter you could sell them to a lot of benchers.

+1. I might buy one if you make custom orders because my fluke only has one input.

First technical snag: I need to learn how to many Cadsoft Eagle libraries, so I can add these plugs: http://www.omega.com/pptst/PCC-OST-SMP.html

Got most of the schematic made up at least, that's a good start.

Those K sockets are considered miniture btw ed, incase you where wondering. Standard sockets are the round prongs.

Yup, I got that figured out.
I need to make a library for 'em though, the only one I've found is broken

Omega didn't have one?

Hmmm... Me thinks I know this mystery guy....

Lookin' forward to seein' how this goes!

Good project! I built a single channel thermocouple thermometer based on an AD595 with a 16x2 LCD. I also had plans for a multi-channel USB version (including voltage monitoring and fan control) but it never materialized due to a lack of motivation to bench.

Here is the interface I designed:



That Maxim chip looks good but you'll be lucky to get hold of them (Maxim are notorious for holding back supply). Good luck with the project!

Thanks!
Digikey has a few hundred of 'em.
Maxim sent me four as engineering samples