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Multimeter with inductance?

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  • #31
    Originally posted by Reader View Post
    I think the blades are one sided edge style connections made of PCBoard material. I could not find a photo showing the other side of those blades. That would clear up the situation.
    This tear down thread should explain it the jacks are split to allow for kelvin measurements.
    https://www.eevblog.com/forum/testge...-and-teardown/Click image for larger version

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    nosaj
    Binkie McFartnuggets‏:If we really wanted to know the meaning of life we would have fed Stephen Hawking shrooms a long time ago.

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    • #32
      Originally posted by Reader View Post
      I think the blades are one sided edge style connections made of PCBoard material. I could not find a photo showing the other side of those blades. That would clear up the situation.
      You are correct. I took my TL-21 apart. Sorry I can't post a photo right now.
      What I don't understand is why there is no 4 probe accessory and no mention of 4 wire Kelvin type measurement in the operation section of the manual?
      Unless those 3 slots are a standard type connector, there is no way to hook up 4 probes.

      (edit: I do still need to watch that EEV video, hopefully it will clear everything up)
      "Everything is better with a tube. I have a customer with an all-tube pacemaker. His heartbeat is steady, reassuring and dependable, not like a modern heartbeat. And if it goes wrong he can fix it himself. You can't do that with SMD." - Mick Bailey

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      • #33
        Back side of PCB note the 3 connection points at the bottom 2 are split to allow for Kelvin measurements
        Click image for larger version

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        The last link I posted I think is easier to consume than the video by Dave from eevblog.
        nosaj
        Last edited by nosaj; 12-28-2018, 11:44 PM.
        Binkie McFartnuggets‏:If we really wanted to know the meaning of life we would have fed Stephen Hawking shrooms a long time ago.

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        • #34
          Thanks nosaj.
          Split banana's are definitely new to me. Still think it's very odd there is no mention of it or of an accessory available in the instruction manual.
          "Everything is better with a tube. I have a customer with an all-tube pacemaker. His heartbeat is steady, reassuring and dependable, not like a modern heartbeat. And if it goes wrong he can fix it himself. You can't do that with SMD." - Mick Bailey

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          • #35
            Originally posted by g1 View Post
            It does not seem to have kelvin 4 wire capability. It has 2 probe ports and 'shield'. Only 3 terminals of the meter are used at a time.
            On the adapter, the 3 blade terminals are used, the other 3 are 'dummies' and only used for physical support.

            [ATTACH=CONFIG]51686[/ATTACH]
            Yes it does have four-wire support. I have one too. The flat blades have copper on the two sides, and glass-epoxy PWB material between.

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            • #36
              Originally posted by g1 View Post
              Thanks nosaj.
              Split banana's are definitely new to me. Still think it's very odd there is no mention of it or of an accessory available in the instruction manual.
              This trick came from General Radio, from which the DE-5000 design came.

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              • #37
                So can anyone link a 4 wire probe set that will work with these split banana or the double sided blade terminals?
                "Everything is better with a tube. I have a customer with an all-tube pacemaker. His heartbeat is steady, reassuring and dependable, not like a modern heartbeat. And if it goes wrong he can fix it himself. You can't do that with SMD." - Mick Bailey

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                • #38
                  Looks like your stuck using the tl-21 adapter and modifying a set of kelvin cables.
                  Could not find what your asking for.
                  http://dexterslab2013.blogspot.com/2...onversion.html
                  nosaj
                  Binkie McFartnuggets‏:If we really wanted to know the meaning of life we would have fed Stephen Hawking shrooms a long time ago.

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                  • #39
                    Originally posted by nosaj View Post
                    Looks like your stuck using the tl-21 adapter and modifying a set of kelvin cables.
                    Could not find what your asking for.
                    http://dexterslab2013.blogspot.com/2...onversion.html
                    nosaj
                    Yes, I think this is the only way. I could not find any such thing as a 'split' single banana plug. All searches turn up 'dual banana' plugs, which is a different thing.
                    I have no idea how they came up with the receptacles (split single banana) on the meter itself and what plug is supposed to mate with it. And if there were such a plug, what would prevent it from rotating so it shorts the 2 sides together?

                    So, technically, this meter supports 4 wire measurement, but there are no commercially available accessories to do so unless you build your own.
                    "Everything is better with a tube. I have a customer with an all-tube pacemaker. His heartbeat is steady, reassuring and dependable, not like a modern heartbeat. And if it goes wrong he can fix it himself. You can't do that with SMD." - Mick Bailey

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                    • #40
                      I looks as if the meter is layed out for 4-wire operation, i.e. separate current source and voltage measuring circuits. As it also allows 2-wire measurement, the banana receptacles need to provide a shorting function when inserting a normal banana plug to connect source and meter circuits.
                      In other words, the split contact banana receptacles are necessary to allow 4-wire measurement with no bananas inserted.
                      Once banana plugs are inserted into the +/- receptacles and the 2 halves are shorted, the 4-wire system is converted to a 2-wire configuration.
                      Last edited by Helmholtz; 12-29-2018, 05:37 PM.
                      - Own Opinions Only -

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                      • #41
                        Originally posted by Helmholtz View Post
                        I looks as if the meter is laid out for 4-wire operation, i.e. separate current source and voltage measuring circuits. As it also allows 2-wire measurement, the banana receptacles need to provide a shorting function when inserting a normal banana plug to connect source and meter circuits.
                        In other words, the split contact banana receptacles are necessary to allow 4-wire measurement with no bananas inserted.
                        Once banana plugs are inserted into the +/- receptacles and the 2 halves are shorted, the 4-wire system is converted to a 2-wire configuration.
                        That's exactly right.

                        IET no longer sells the DE-5000 (or its successor DE-6000?), but here here is the IET manual (from 2011) on the DE-5000: https://www.ietlabs.com/pdf/Manuals/DE_5000_im.pdf

                        It appears (page 37 top) that the split-pin banana jacks are used only to compensate paths within the instrument, so no split-pin dual banana plugs are used or provided.

                        IET also provides a 78-page primer on LCR measurements: https://www.ietlabs.com/pdf/applicat...%20Edition.pdf

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                        • #42
                          The split receptacle contacts act as switches. Without them (or a separate switch) 4-wire operation via the blade contacts would not be possible.
                          - Own Opinions Only -

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