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| Kelvin leads for DMM |
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| Traceless:
--- Quote from: Someone on March 10, 2022, 09:32:34 pm --- --- Quote from: Electro Fan on March 10, 2022, 09:15:47 pm ---Anyone up for posting a summary explanation or "theory of operations" regarding the role of the shield and the practical connection considerations? Maybe touch on how a fifth conductor is supposed to work with 4 wire Kelvin leads. --- End quote --- https://www.tek.com/en/documents/product-article/keithley-low-level-measurements-handbook---7th-edition --- End quote --- I just took a look at that Tektronix article, can anyone explain why they measure resistance in watts? |
| tooki:
--- Quote from: Traceless on March 12, 2022, 09:07:15 am --- --- Quote from: Someone on March 10, 2022, 09:32:34 pm --- --- Quote from: Electro Fan on March 10, 2022, 09:15:47 pm ---Anyone up for posting a summary explanation or "theory of operations" regarding the role of the shield and the practical connection considerations? Maybe touch on how a fifth conductor is supposed to work with 4 wire Kelvin leads. --- End quote --- https://www.tek.com/en/documents/product-article/keithley-low-level-measurements-handbook---7th-edition --- End quote --- I just took a look at that Tektronix article, can anyone explain why they measure resistance in watts? --- End quote --- They don’t: That’s practically guaranteed to be a typo caused by conversion from one file format to another. If you download the book as a PDF (the “DOWNLOAD FILE” button at the top of the page), it uses the ohms symbol there. |
| Traceless:
@tooki: Yeah that was my first thought as well but they mad a lot of typos then. At first I thought it might be an auto-conversion issue, but it is not consistent even on the screenshot I posted there is actually the Omega used for resistance correctly as well. They just switch back and forth between the "\$\Omega\$" and "W". The first time it already happens in 1.1: --- Quote from: Keithley link=https://www.tek.com/en/documents/product-article/keithley-low-level-measurements-handbook---7th-edition ---Generally, these instruments are adequate for measurements at signal levels greater than 1µV or 1µA, or less than 1GW. --- End quote --- |
| tooki:
--- Quote from: Traceless on March 12, 2022, 09:25:02 am ---@tooki: Yeah that was my first thought as well but they mad a lot of typos then. At first I thought it might be an auto-conversion issue, but it is not consistent even on the screenshot I posted there is actually the Omega used for resistance correctly as well. They just switch back and forth between the "\$\Omega\$" and "W". The first time it already happens in 1.1: --- Quote from: Keithley link=https://www.tek.com/en/documents/product-article/keithley-low-level-measurements-handbook---7th-edition ---Generally, these instruments are adequate for measurements at signal levels greater than 1µV or 1µA, or less than 1GW. --- End quote --- --- End quote --- Believe me, it’s a conversion issue. Who knows what the original source format is. But it’s eminently possible to have inconsistent conversions. Or the conversion was consistent, but the person using search-and-replace to fix it didn’t catch them all. Again, the PDF is correct, just look at it. |
| Electro Fan:
--- Quote from: Electro Fan on March 10, 2022, 04:07:22 am --- --- Quote from: Someone on March 10, 2022, 12:41:01 am --- --- Quote from: Electro Fan on March 09, 2022, 11:31:39 pm --- --- Quote from: Someone on March 09, 2022, 11:14:01 pm --- --- Quote from: Traceless on March 09, 2022, 09:27:54 pm ---@Hydron: Thanks for reporting back on your experience the GW-Instek ones I linked in my original post. Before you and alm mentioned it i didn't recognize how wide the clip-tips are. Indeed I was looking for something more filigree. --- End quote --- Tiny kelvin clips: https://www.eevblog.com/forum/testgear/best-way-to-securely-attch-probe-to-a-passive-smd-component/msg1310826/#msg1310826 BYO cabling, "standard" 0.025" pin header plugs. They will take more than the 1A rated current. --- End quote --- Thanks for posting. The product in the photos at your link above looks good but the link at your link doesn't seem to go to the product and the product number doesn't seem to be findable. Maybe a double check? Thx http://www.keysight.com/my/faces/partDetail.jspx?partNumber=1400-3652 Edit: found it, I think: https://www.keysight.com/my/partDetail/1400-3652 --- End quote --- Or if you read that (short and concise) thread, a whole 2 posts along: https://www.eevblog.com/forum/testgear/best-way-to-securely-attch-probe-to-a-passive-smd-component/msg1310906/#msg1310906 you get the OEMs part number. --- End quote --- Thanks! Looks like same part at a better price. https://www.newark.com/hirschmann-testmeasurement/972416100/clip-test-micro-smd-black-mln/dp/67C8450 --- End quote --- I ordered a pair of these. They are pretty small: about 2.5 cm long with the plastic housing and about 5mm wide on the jaws, so they are a good size for SMDs but they are a bit finicky to keep in place as you try to make measurements. If you have steady hands and your leads are long enough to reach your DUT they will hold, somewhat. You have to make your own leads. I had some female to female Dupont connectors about 6 cm long that attached to the male pin inside each jaw clip handle and then I extended those 60 cm with 22 gauge solid wire and then attached the wires to banana jacks. When it was all put together they read within about 0.1 milliohms of the TLDK1 Kelvins on my reference 45 cm copper wire. Unless you are really into low ohm SMD readings I'd say the TLDK1 leads and clips are a better use of the budget but it was an interesting look-see. |
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