Products > Test Equipment
DIY scan card for Keysight 34970A
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voltsandjolts:

--- Quote from: H.O on June 10, 2022, 03:14:45 pm ---Then, when repeated about two minutes later I get the EXACT same values as above. Wait another minute or two:
0x140E = 20.005°C
0x140E = 20.005°C

--- End quote ---

Hmm, when I program my card to return 0x140E for both CJ readings, I get 19.344°C
Close, but not exact as I expected ???

Edit:
I wonder if the dmm has an internal temperature sensor, and that is also included (to a small extent) into the weighted temperature average. Hmm.

...No. Can't be. For same hex values I get exact same TJ some 15mins later. If there were a third sensor in the mix, there would be some small change.

It could be a time series average in the dmm, so 0x140E might be 19.344°C, and HO's card was cooling a little and showing time average of 20.005°C (delayed reading).....No. HO's reading show the card is warming slightly, over a few minutes.
tv84:
Why not read the temp for all the hex values and draw the line with the comparison? Or it's to cumbersome?

With that you could probably discover what is the difference rule.
voltsandjolts:
Sure, but HO can only do a few points with his setup.
I just wanted to see a perfect match to my setup with a few points.
But maybe dmm averaging makes this impossible.
strawberry:
70A cant find internal temp sensor
nothing interesting
5118   20.031   5124   19.996
5134   20.005   5134   20.005
5172   20.172   5182   20.226
10880   43.629   10606   41.805
15100   62.785   13802   55.437
18302   77.375   16294   66.004
voltsandjolts:
I have updated the first post in this topic to include the design files for this card.
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