Hello,
I'm trying to amplify a thermocouple signal and read it via velleman K8055 board. Im using LM258P operational amplifier. I'm connecting it like this:
**broken link removed**
I connect thermocouple parallel with multimeter, to check readings. K8055 input is 8bit.
Problem is that when i connect it the computer shows me 19bars ar 21C° and it is increasing... in 10 mins there is 44 bars and stops increasing, though multimeter shows stable 21C°.. I have no idea why is this happening? maybe its because of too much noise? or i should connect + of the thermocouple via ~10MOm resistor to ground?
any help would be very welcome.
I'm trying to amplify a thermocouple signal and read it via velleman K8055 board. Im using LM258P operational amplifier. I'm connecting it like this:
**broken link removed**
I connect thermocouple parallel with multimeter, to check readings. K8055 input is 8bit.
Problem is that when i connect it the computer shows me 19bars ar 21C° and it is increasing... in 10 mins there is 44 bars and stops increasing, though multimeter shows stable 21C°.. I have no idea why is this happening? maybe its because of too much noise? or i should connect + of the thermocouple via ~10MOm resistor to ground?
any help would be very welcome.
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