K-type Thermocouple Sensor


Thread Starter

Arifur Rahman


I'm at the final edge of completing my thesis project entitled 'Construction and Performance test of a Temperature Controller for an Electric Heater'.

I've constructed the cicuit and built the logic in Arduino so that the system can control a heater within a temperature range of 750-800 dgr C. What I'm facing problem with is the sensor that I'm using -- a K type thermocouple sensor. It gives 0.1mV for every 6 dgr C approximately which is quite low. So, I've amplified it with an amplifier circuit. This finally resulted in a huge fluctuation. For example it's showing a range from 550 dgr C to 570 dgr C for actual 560 dgr C. I don't know how to stop or minimize this fluctuation without changing the sensor. I will really appreciate any kind of help..


Bob Peterson

it really is not that much of a fluctuation. take a look at the specs on the amplifier and you could well find it is within the amplifier specs. you are talking about something that needs to be pretty precise to work the way you want. the amplifier you selected may just not be up to the task.

Yout mv/Deg C is too low for Type K T/C, it should be more like 4 mv/100 Deg C.

Either the t/c is not properly identified, or your extension leads (if not continuous) are not properly installed.

How is your T/C made and what reference junction are you using?

T/C's can be notoriously sensitive to many factors though some are more suited to the high temperatures than others. suggest that you use a platinum RTD or Pt thermocouples suitable to the temperature range.