Thermistor Construction Journal

Along with the LabView program, another component of bending fibers will be to determine the temperature of the water and to make that information available to the program.

At first, I had thought that our best bet as far as reading/recording water temperature was to make a thermistor (as seen below).

After reading the material above, I have found two (cheap) ways to read a thermocouple accurately:

1. Create something in the software that compensates for the room temperature factor at the cold junction. If we end up using the thermistor to read the temperature at the cold junction then we will be introducing the error from one temperature measurement to another. Although the thermistor will read the water temperature within acceptable error, adding more error into the calculation seems unnecessary to me.

2. Follow the diagram above and create a hardware approach to cold junction compensation. After determining the voltage output of a type J thermocouple at zero degrees Celsius, I can introduce that voltage at the cold junction site. By following the circuit above, I would probably be able to construct a circuit that would have cold junction compensation and amplification for the signal. My concerns for this approach involve time constraints and the intricacies of this setup.

Although, after having found this, I think the problem may be solved.

[[media:Thermocouple_op_amp.pdf|Op amp designed for a type J thermocouple, with cold junction compensation]]