Catching up on things.
Working on my Raspberry Pi lately.
Got my thermistor wired up.
I used a Thermocouple Amplifier MAX31855 breakout board and a Type-K Glass Braid Thermocouple from Adafruit.
Took a code sample from my Pi class for using the SPI protocol in Python. I combined that with an Arduino Sketch from Adafruit for the MAX31855 and surprisingly I got results the first time. Graphing the results against known temperatures (from my temperature sensing multi-meter) I programmed in software adjustments — not completely accurate, but close enough for now, within a couple of degrees.
Here is the Python program running on the Pi.
It takes a temperature reading every 2 seconds. The first column is the raw output from the MAX31855. The second column has been put through a software converter to give me Celcius. The last column is in Fahrenheit.
Here is the whole setup on a breadboard.
The Pi on the left. Breadboard on right with the MAX31855 in the middle of the board. The orange-yellow wire is the thermistor itself. Also notice a Pi Plate (blue) in the upper left. This will hold the project when it comes to soldering time. In the middle (blue on red) is a relay. This will be used to control the heater on the print bed.
Also have recently picked up 36 .22 ohm 5w resistors from U-Do-It Electronics. I will cement them on a replacement print tray made of aluminum in a combination of series and parallel. Power them with a power supply from a cast-off computer I got from a buddy.