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Multimeter with inductance?

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  • #16
    Originally posted by Helmholtz View Post
    Yes, it measures Q/D. See datasheet "Features" and "Display". I did compare the meters. Even compared both to the >10k $ HP impedance analyzer in our lab. I tend to make sure before I recommend something.
    I wasn't precise enough. Mention of D and Q isn't enough. What's needed is numerical specification of the range of D or Q values over which the meter will achieve stated accuracy. I did not find this in the ELC131D datasheet.

    The ELC131D was standard lab equipment with my EEs. I've had mine for 8 years or so.
    That's good to know. Not everybody is up for $250.


    I am used to search the global market.
    In the US, this was difficult until relatively recently. Now it's easy, and I buy many things directly from Europe and China.

    Like Jens Putzier: https://www.jensputzier.com/. This is a one-man shop, but he has stuff that's hard to get in the US.

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    • #17
      What's needed is numerical specification of the range of D or Q values over which the meter will achieve stated accuracy. I did not find this in the ELC131D datasheet.
      If you look at the pdf spec, you will find that accuracy is specified for DF(D)<0.5, i.e. Q>2.0. I never cared, because I verified by direct comparison. Just measured a lossy steel core inductor:

      ELC131D:
      Ls= 636.4ÁH/Q= 1.88 @1kHz and Ls= 1.19H /Q= 1.37 @ 120Hz

      PT 2170:
      Ls= 639.1ÁH/Q= 1.91 @1kHz and Ls= 1.20H/ Q= 1.42 @120Hz


      Not everybody is up for $250.
      That seems to be matter of priorities. My ECL131D was about 150€ when new.
      The ELC131D has been around since the early 90s.

      Both my digital meters work better with low-Q inductors than my old Philips which uses a Maxwell-Wien bridge.
      Last edited by Helmholtz; 12-25-2018, 03:21 PM.
      - Own Opinions Only -

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      • #18
        Originally posted by Helmholtz View Post
        If you look at the pdf spec, you will find that accuracy is specified for DF(D)<0.5, i.e. Q>2.0. I never cared, because I verified by direct comparison. Just measured a lossy steel core inductor:

        ELC131D:
        Ls= 636.4ÁH/Q= 1.88 @1kHz and Ls= 1.19H /Q= 1.37 @ 120Hz

        PT 2170:
        Ls= 639.1ÁH/Q= 1.91 @1kHz and Ls= 1.20H/ Q= 1.42 @120Hz
        Hmm.. Many guitar pickups have Q values of 1.0 and below.

        That seems to be matter of priorities. My ECL131D was about 150€ when new.
        The ELC131D has been around since the early 90s.
        Well, yes. There are many needs and few dollars.


        Both my digital meters work better with low-Q inductors than my old Philips which uses a Maxwell-Wien bridge.
        This is odd. What is the model number of the old Philips?

        I built my bridges from discrete components, each componet's value having been measured to 1% before assembly.

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        • #19
          Hmm.. Many guitar pickups have Q values of 1.0 and below.
          Never saw one. But both meters are within 1% with an inductor having a Q of 0.4.

          What is the model number of the old Philips?
          PM 6302
          - Own Opinions Only -

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          • #20
            typo

            Originally posted by Helmholtz View Post
            Never saw one. But both meters are within 1% with an inductor having a Q of 0.4.
            I recall discussions of units with very low Q, with lots of #42 wire. Probably for a Base <something>.

            In my notes (of 21 February 2005): "The Eastman" by Kent Armstrong, Model HJGS-1. Rdc = 7.978 Kohms. Test at 1 KHz. 2.776 Henrys, Rac= 10.99 Kohms. (The excess of Rac over Rdc is 3.012 Kohms; this is the eddy current burden, which does count in Q computation.)

            At 1000 Hz, Reactance is 2.776*(2 Pi 1000) = 17,442 Ohms. The Q is this divided by 10,992 ohms, or 1.58. I think that is the smallest I have measured.

            PM 6302
            I found the service manual. It sure looks plausible; don't know why there would have been a problem. Hmm - it may have been hard to detect when the bridge was actually balanced if one is only measuring the amplitude of the bridge null signal, and not the phase. I recall having to bounce between phase and amplitude to find the null. I'll read the manual more deeply.

            I forgot to mention when this all happened. I built the impedance bridge in mid 2004, and very few of the handheld LRC meters of that day worked correctly with pickups.

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            • #21
              The Q is this divided by 10,992 ohms, or 1.58. I think that is the smallest I have measured.
              In an earlier post you wrote "Many guitar pickups have Q values of 1.0 and below." And I replied that I never saw one having a Q that low.

              As indicated above, the ELC131D has been available since around 1993. It works perfectly down to a Q of 0.4 and certainly lower.
              Apart from that, I don't see a need to measure PU inductance to better than say +/- 3%.

              The OP asked for advice regarding L meters suitable for PUs and I recommended a couple that I am familiar with and know that work just fine.
              These ÁC-based LCR meters are much easier to handle than traditional bridges. And they are really accurate.
              - Own Opinions Only -

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              • #22
                I have a question to owners of the DE-5000:

                The spec sheet lists 4-wire (Kelvin) measurement as a feature. Looking at the picture I can spot only 3 receptacles. How is this supposed to work? Are one or two of the receptacles actually coaxial double contacts?
                - Own Opinions Only -

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                • #23
                  Originally posted by Helmholtz View Post
                  I have a question to owners of the DE-5000:

                  The spec sheet lists 4-wire (Kelvin) measurement as a feature. Looking at the picture I can spot only 3 receptacles. How is this supposed to work? Are one or two of the receptacles actually coaxial double contacts?
                  I have the meter but not the Kelvin adapter. Maybe this video will show you something?
                  http://electricalandelectronicsandst...lvin-clip.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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                  • #24
                    From what I have read, the socket itself is '4 wire'.

                    The TL-21 lead adapter joins the wires inside the adapter box.
                    Click image for larger version

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                    The TL-22 SMD tweezers join the wires very near the tip.
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                    Here is a nice 'teardown' of the unit: https://www.eevblog.com/forum/testge...-and-teardown/

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                    • #25
                      Thanks!
                      It seems that for the 4-wire measurement the Kelvin adapter is required, which uses the blade contacts plus at least one of the normal receptacles.
                      - Own Opinions Only -

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                      • #26
                        Originally posted by Helmholtz View Post
                        Thanks!
                        It seems that for the 4-wire measurement the Kelvin adapter is required, which uses the blade contacts plus at least one of the normal receptacles.
                        Edit: 4 wire measurement is supported. Each single banana socket is split in 2 inside. The blade terminals are double sided, so 2 conductors per blade.
                        Unfortunately, no accessories are sold for 4 wire measurement with this unit. You must build your own by modification of the TL-21 or TL-22.

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                        Last edited by g1; 12-29-2018, 02:13 AM.
                        "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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                        • #27
                          That's what I suspected originally. Means that the spec sheet is cheating. Confused by the improvements shown in the video. Could still be a 3-wire measurement, which is better than 2 wires if done correctly. This can eliminate/compensate lead wire resistance but not contact resistance.

                          Anyway, the PeakTech 2170 recommended above does full 4-wire measurement. Absolutely not necessary for PU measurements but highly welcome when measuring ESR or Q of caps and for designing a dummy load emulating speaker impedance .
                          Last edited by Helmholtz; 12-28-2018, 09:22 PM.
                          - Own Opinions Only -

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                          • #28
                            The tear down article referenced in post #24 seems to indicate that there are 2 contacts on each of the + and the - blade contacts. Therefore, it's likely that the adapter box does provide true 4 wire connection. The dual contacts are visible in the photos in post #24. (Same photos as used in the tear down article)
                            Keep learning. Never give up.

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                            • #29
                              Originally posted by Reader View Post
                              The tear down article referenced in post #24 seems to indicate that there are 2 contacts on each of the + and the - blade contacts. Therefore, it's likely that the adapter box does provide true 4 wire connection. The dual contacts are visible in the photos in post #24. (Same photos as used in the tear down article)
                              This would make sense. It means that the two contacts on the blades are separated by some insulating carrier. Not obvious to me from the pictures.
                              - Own Opinions Only -

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                              • #30
                                Originally posted by Helmholtz View Post
                                This would make sense. It means that the two contacts on the blades are separated by some insulating carrier. Not obvious to me from the pictures.
                                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.
                                Keep learning. Never give up.

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