Measuring temperature is the most common measurement task.  There are numerous devices available for measuring temperature.  Many of them are built using one of these common sensors.

• Thermistor
• Thermocouple
• LM35 Integrated Circuit Temperature Sensor

        The purpose of this laboratory is to get time response data for the three sensors you were introduced to labs week.  Here are links to LabVIEW programs you can use.

• NTempsHydra.vi - to measure temperature from the Hydra.
• NVoltsHydra.vi - to measure voltage from the Hydra.
• ResetHydra.vi - A "sub-vi" you need to reset the Hydra.
• 1Temp.vi - A sub-vi that will take one temperature measurement on the Hydra.
• 1VoltHydra.vi - A sub-vi that will take one voltage measurement on the Hydra.

• You should have all the files above on your desktop.  You can click on each link and save to the desktop, or you can find the NMeas folder in my public space and copy the entire folder to the desktop (best).  You only need to double click the NTemps or NVolts files to start and run them in LabVIEW - but they have to be taken out of the network folder!
• Once you have the files together in a single folder on your desktop,
• Start NTempsHydra.vi to measure temperature using the thermocouple attached to terminals 21 (yellow lead) and 22 (red lead).  Note that these terminals (21 and 22) are the connections for channel 1 for the Hydra.  (For example, if you were doing a manual temperature reading using the front panel, you would need to set to channel 1.)
• You need to connect the yellow lead of the thermocouple to the top connector for Channel #1 (Terminal #21) and the red lead of the thermocouple to the bottom connector (ground?) for Channel #1 (Terminal #22).  Both of those connections are made to the connector strip on the top of the Hydra Data Acquisition Unit.
• Start NVoltsHydra.vi to measure voltages using the LM35 and the voltage divider circuit for the thermistor.  Both sets of measurements should be taken from the front panel connection points on the Hydra.
• For both the LM35 and the thermistor circuit, you need to supply 5v to the circuit board.
• In your lab notebook record any circuitry you use, and any pertinent points regarding the equipment you use.
• Note any other features of each sensor that will help you for your project or make things more difficult.

• Connect each sensor.  Here are links to using each sensor in a measurement.
• Thermocouples
• LM35s
• Thermistors
• For each sensor you need to get data in two situations:
• As the sensor heats up (rising time constant behavior)
• As the sensor cools down to ambient temperature (decaying time constant behavior)
• That data should be stored in a computer file.
• Use a different, understandable name for each file.  The program will prompt you for a file name.  Suggested file names are things like ThermistorUp.txt, etc.
• Before you leave lab be sure that you can bring your data up in Excel (to test that you have a good data file) and that you can plot the data to see that it looks like what you expect.
• Estimate the following for each sensor.
• The time it will take for the sensor to get within 1^oC when the sensor is in good thermal contact with the temperature environment being measured and the temperature sensor starts at 25 ^oC and goes to 50 ^oC.  (That means to measure the time it takes to get to between 49 ^oC and 51 ^oC.)
• The time it will take for the sensor to get within 1^oC of the final value when the sensor is in air at a constant temperature and the temperature sensor starts at 25^oC and goes to 50^oC.  In other words, when will the temperature sensor reach 49^oC?
• The time it will take for the sensor to get within 0.1^oC for the two situations above.  (i.e., between 49.9 ^oC and 50.1 ^oC.)
• The time it will take for the sensor to get within 1^oC when the sensor is in good thermal contact with the temperature environment being measured and the temperature sensor starts at 50 ^oC and goes to 25 ^oC.
• Explain why there is a difference in the speed of the response in the various situations above.
• Your report should show calculations for the time constant(s) for each device, and should show the results using the three methods.  Tabular presentation of the results is best.
• Finally, you should - as best possible - explain your results.  Why would the time constant be different going up and going down.