Heat is dangerous! Evaluate the risk and make your go/no-go decision!
I have had issues with the thermocouple chip getting too hot when air temp is above 90F. It is in a metal box, 2' away from the kiln. Last firning, when the kiln was within 30C of cone 6, it started under reading. I added a computer muffin fan to cool the electronics.
Parts and pieces: I think it adds up to ~ $70 and some shipping.
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Raspberry pi: any of these will work, $10 Zero W is cheapest, but a Pi 3b runs much faster and will give a desktop.
https://www.adafruit.com/product/3775 https://www.adafruit.com/product/3055 https://www.adafruit.com/product/4027 https://www.adafruit.com/product/3400
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5V power supply: for the Pi
https://www.adafruit.com/product/1995
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MicroSD card: you will also need a way to write the image, e.g. usb adapter
https://www.amazon.com/SanDisk-microSDHC-Standard-Packaging-SDSQUNC-032G-GN6MA/dp/B010Q57T02/ref=sr_1_14?keywords=micro+sd&qid=1552005480&s=gateway&sr=8-14
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MAX31856 thermocouple module:
https://www.adafruit.com/product/3263
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Female <=> Female jumper wires:
https://www.adafruit.com/product/266
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20x4 LCD w/ i2c backpack: it will print to console too.
https://www.amazon.com/gp/product/B01GPUMP9C/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1 or https://www.adafruit.com/product/198 https://www.adafruit.com/product/292
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High temperature (2372 F) type K thermocouple:
https://www.amazon.com/Temperature-Thermocouple-Ceramic-connector-CR-06/dp/B0713X6XG3/ref=sr_1_25?keywords=k-type&qid=1551683054&s=gateway&sr=8-25
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Download Raspbien Stretch or newer and write it to the MicroSD:
https://www.raspberrypi.org/downloads/raspbian/ boot it up expand the partition, it ask on first boot configure network update software 'apt-get update' and 'apt-get upgrade'
Wiring:
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fritz: 'https://raw.githubusercontent.com/BlakeCLewis/kiln_logger/master/logger_bb.png'
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Pin-Out:
Device PI ---------- ------- RPLCD VCC: 5V RPLCD GND: GND RPLCD SDA: GPIO 2 RPLCD SCL: GPIO 3 MAX31856 3vo: 3.3v MAX31856 GND: GND MAX31856 SDO: GPIO 9 MAX31856 SDI: GPIO 10 MAX31856 CS: GPIO 8 MAX31856 SCK: GPIO 11
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Install project files:
git clone [email protected]:BlakeCLewis/kiln_logger.git
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Install sqlite3:
sudo apt-get install sqlite3
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Configure raspberry pi interfaces:
sudo raspi-config #enable interfaces ssh, ic2 & spi
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Instal RPLCD for the 20x4 lcd:
sudo pip3 install RPLCD
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Install MAX31856 Module:
cd sudo apt-get update sudo apt-get install build-essential python3-pip python3-dev python3-smbus git git clone https://github.com/adafruit/Adafruit_Python_GPIO.git cd Adafruit_Python_GPIO sudo python3 setup.py install cd git clone [email protected]:johnrbnsn/Adafruit_Python_MAX31856.git cd Adafruit_Python_MAX31856 sudo python3 setup.py install
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test modules:
cd ~/kiln_logger python3 display.py python3 max31856_test.py
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create the database:
sqlite3 ~/kiln_logger.sqlite3 CREATE TABLE firelog(RunID number, datime datetime, t number); .schema .exit
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run the logger
cd ~/kiln_logger ./logger.py -i <intger Run_ID> -s <interval in seconds>
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access data:
ssh pi@<pi ipaddres> sqlite3 kilnlog.sqlite3 select * from firelog where runid=420 order by datime asc;