Temperature sensors

Using Arduino Sensors
1

Hi.

I am having trouble with my 3 type k thermocouples. They are all connected to a AD595 amplifier.
When i only had one amplifier and one thermocouple i had no problems, but now when a have 3 thermocouples and 3 AD595 the measurements(with multimeter) is 0.21 V, 0.20V and 1.5 V corresponding to 21, 20 and 150 degree celcius.
The 3 AD595 are mounted on a printboard with common ground and same powersupply.

Any one who knows what the problem is?

Best regards
Bastian Gaardahl

2

Hi, what happens if you swap thermocouples around, do the readings move with the thermocouples, or stay with the relevant amplifier.
This will help, isolate the problem, also can you post a copy of your circuit, and a photograph please.

Tom... :slight_smile:

3

TomGeorge:

The problems seems worse when only 1 or 2 of the thermocouples are attached. making the third a open circuit.

A haven't noticed any difference when changing the 3 thermocouples.