K8055 with Pt100 or similar NTC

I could use a digital thermocontroller.

  • Yes.
  • Of course.
  • Every day!!
  • No, I already have one :stuck_out_tongue:

0 voters

Hi
I want to control a heating element (for hobby-chemistry) over software. For that I need to read temperature in the range -10 to +180 °C with a fair accuracy. I already have all the equipment, a temperature probe (of questionable chinese origin), the K8055 (which I successfully used in other projects), some 40A relais etc…
I know there are some similar posts about this topic (and I also googled a lot) but there are some issues I still don’t really get:

  • Do I have the install R8 and R9, what are they for and how do I determine their values?

  • Has anyone developed a circuit for this purpose, which works? Or any idea where I can find one?

  • Existing circuits may need to be modified when I have a different NTC, right? So, when my NTC has a lower (or greater) overall resistance how do I find out, which part is to be modified?

  • Existing solutions often employ an amplifier between the sensor and the analog input but don’t mention the necessary details. Has anyone a circuit or a solution for this?

Feel free not to answer every single question I’m thankful for every little bit!
Thanks in advance!
Maniacy

//EDIT: If you help me get this working I will of course supply circuits, program and source for a control and monitoring/logging device for a magnetic stirrer (or similar device) using 2 relais, 2 NTCs, 1 analog contact thermometer, and a few switches (for manual override, event recording, etc.) Looks so far: easypics.us/pics/magstir_screen.html

Yes, this topic is discussed in several posts in this forum. Here a list of some of the threads:
About temperature measurement:
[forum.vellemanprojects.eu/t/using-a-k8055-to-take-temperature-readings/1399/1)
[forum.vellemanprojects.eu/t/k8055-et-pt100/879/1)
[forum.vellemanprojects.eu/t/datalogger-k8047/639/1)
About the gain adjustment:
[forum.vellemanprojects.eu/t/k8055-analog-input-control-vref/1432/1)
[forum.vellemanprojects.eu/t/vm110-analogue-input-drift/1041/1)

First you have to check the nominal resistance value of your temperature sensor.
Then take a resistor of the same value and connect it between the analog input and +5V of the card. Connect the temperature sensor between analog input and GND.

In the manual there is example how to calculate proper values for R8 and R9. Maybe you have to use trial and error method to find the best values for the resistors.

Thanks, this really covers it!