Pico Technical Support and Discussion Forum

Guest · Posted: Thu Apr 26, 2007 1:26 pm Post subject: TC-08 resolution [µV]

I intend to monitor temperatures at several positions inside and on the outside of a cryo liquid storage vessel which will be pre-cooled by liquid nitrogen (-196°C) and then filled with liquid helium (-269°C).

Is this possible by using a TC-08 in combination with type K thermocouples within a reasonable resolution, let's say of about 1°C?

The ouput of such a thermocouple at -269°C is about -6.5 mV what is well within the range of the voltage measurement of the TC-08 and also within the range of conversion of type K voltages to temperatures, according to the specifications. I'm not so much concerned about the accuracy (of absolute readings), but more about the resolution. At -269°C the sensitivity of type K thermocouples drops (from about 40 µV/°C around room temperature) to about 1 µV/°C.

My question now: what is the resolution in voltage measurements of the TC-08 (in µV)?

kind regards

ziko · Posted: Thu Apr 26, 2007 4:14 pm Post subject:

Hi, and thank you for your post.

There are a number of thermocouples that can measure this temperature range, E, K and N type thermocouples. E type thermocouple tend to perform a little better at lower temperatures, but I would do research on which of these thermocouples is best suited for you.

In terms of the uV resolution for the USB TC08 it would be 0.149uV.

I hope this helps, if you have any further questions please do not hesitate to contact me , kind regards.

alan · Site Admin Joined: 25 May 2006 Posts: 45

Hi,

The following application note gives more information on the different types of thermocouples - http://www.picotech.com/applications/thermocouple.html

Regards
Alan

Guest · Posted: Mon Apr 30, 2007 12:20 am Post subject: Buffer - Pico tc08

HI

I am an engineering student.
I have a Pico Technology TC08 (USB) and in my studies I have to simulate his properties in LabVIEW.
I need an example of function "usb_tc08_get_temp" in LabVIEW because I do not know where and how the buffer was saved.

Best regards
Adriana Gomes

ziko · Posted: Mon Apr 30, 2007 9:00 am Post subject:

Hi and thank you for your post.

If you do a custom installation or re-install the software and select the programming examples as shown in the file attached. This will create programming examples located by default in the following location

c:\Program Files\Pico Technology\Pico Full\Examples

Hope this helps.

Kind regards

Adriana · User Joined: 29 Apr 2007 Posts: 2

I have already re-installed the software and did everything you told me but the only LabVIEW example i found was the usbtc08.vi. This VI only demonstrates the use of the get_single function. I need a VI that uses the get_temp function, i.e. that uses streaming mode.

Best regards,
Adriana Gomes

ziko · Posted: Wed May 09, 2007 8:41 am Post subject:

Hi ,

We cannot help you write your own code but what we do is provide examples and description of the function calls. If you have a look at the manual this will provide a description of the function calls, the get_temp function is described in page 26 of our manual (27 in adobe).

If you have a specific question then I may be able to help you.

Kind regards.

gruntman · Posted: Wed May 09, 2007 8:38 pm Post subject: TC-08 Labview Example

Adriana,

The attached file will show you how to use the USB TC-08 using the usb_tc08_get_temp method of collecting the data. Let me know if you have any questions...

Regards,

Richard Boyd
http://www.pc-oscilloscopes.com

Adriana · User Joined: 29 Apr 2007 Posts: 2

I need to save more samples per secunde with 8 channels in LabVIEW like I can save when I use the PicoLog Record.
I have the file usb_tc-08_stream_71.vi, but the results are different that I get in PicoLog.
I would like to know how can I get the same results with a vi.
I hope you can help me.

Best regards
Adriana Gomes