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Steve Morgan
Newbie
Joined: 04 Apr 2006
Posts: 1
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 Posted: Tue Apr 04, 2006 1:46 pm Post subject: TC08 mV input |
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Hello,
I am using a TC-08 for logging both K-type thermocouples and mV inputs. Before I connect any of the thermocouples, there appears to be a ground isolation problem.
When I connect a 32 mV input the reading is unstable and reads about 24.xx mV.
1 - Disconnecting the AC ground wire, from the instrument that is producing the 32 mV, changes the mV reading but does not correct the problem.
2 - However, if I unplug the notebook pc from the AC line (making it run from it’s battery) the reading goes to 32 mV and is stable. This would not be a bad solution if I was not running a 4 day test.
I would be grateful for any help you could provide.
Steve |
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Michael
Guru
Joined: 07 Jul 2005
Posts: 93
Location: St Neots, Cambridgeshire
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| Posted: Thu Apr 06, 2006 7:34 am Post subject: |
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Hello Steve,
Your laptop uses a switch moe PSU with a floating ground. YOu will need to earth the TC08 to the same earth as your test rig. You can do this a couple of ways: Earth the TC08 directly from the serial port(if it's a serial port version) or you can earth the chassis of the laptop.
Simply connect a piece of wire to the ground plane of your test rig and to your PC/TC08.
Best regards,
Michael |
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