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| East Tester ET4410 ESR Measure |
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| TimFox:
Since you are approaching self-resonance at 100 kHz, the measured reactance/capacitance will depend on the lead length in your fixture. It only takes 2.5 nH to resonate 1000 uF at 100 kHz. |
| The Electrician:
--- Quote from: mawyatt on August 02, 2022, 06:24:37 pm ---For those of us without a nice Hioki IM3570 we can generate some decent plots of DUT Capacitance Impedance Magnitude and Phase with a scope and signal generator. Simply sweeping the source frequency over the desired range and measuring the amplitude and phase of the voltage across across the DUT and current thru the can yield the result with a little math. --- End quote --- Here as some plots done on the IM3570, with colors set to match yours. One thing that your plots aren't getting right at the extreme frequencies. The phase curve vs frequency should be monotonic. The first one is of a 1000 uF cap of moderate loss: Here is a plot of another 1000 uF cap with lower loss. You can see the effect of lower loss; the curvature of the bottom of the |Z| curve is more rapid the lower the loss: Here are both plots superimposed: |
| The Electrician:
--- Quote from: Martin72 on August 02, 2022, 08:11:20 pm ---So... Today I´ve measured the both panasonic caps at work again, the menu of the ST2830 is not the clearest one. A few minutes ago I did the same again at home on the ET4410, to have it all in one post. The 100µ cap at 120Hz: ST2830 ET4410 103.16µF 103.33µF Xc -12.86 Ohm -12.84 Ohm Q 51.10 51.80 D 0.0196 0.0192 ESR 0.252 Ohm 0.250 Ohm Phase -88.88° -88.89° At 100Khz: 26.50µF 15.40µF -0.071 Ohm -0.104 Ohm 1.607 2.427 0.6185 0.4115 0.038 Ohm 0.043 Ohm -57.86° -67.63° 1000µF at 120Hz ST2830 ET4410 945.91µF 946.8µF Xc -1.402 Ohm -1.401 Ohm Q 28.60 29.04 D 0.035 0.035 ESR 0.049 Ohm 0.048 Ohm Phase -87.99° -88.03° At 100Khz 72.50µF 23.80µF -0.025 Ohm -0.067 Ohm 1.578 3.756 0.632 0.266 0.014 Ohm 0.018 Ohm -57.31° -75.20° At 120Hz they are like twins.. 8) Datasheets: 1000µF/25V FM Type: https://www.micro-semiconductor.com/datasheet/37-EEU-FM1E331LB.pdf 100µF/35V FR Type: https://industrial.panasonic.com/cdbs/www-data/pdf/RDF0000/ABA0000C1259.pdf --- End quote --- Martin72, Would you please post a photograph of the fixturing or Kelvin cable you are using to make measurements of your ET4410 and the meter at work? |
| mawyatt:
--- Quote from: The Electrician on August 03, 2022, 12:12:16 am --- One thing that your plots aren't getting right at the extreme frequencies. The phase curve vs frequency should be monotonic. --- End quote --- That's due to the setup fixturing or lack thereof, just a Proto-Board, Scope Probes, 1K 2W leaded resistor and 1 Meter BNC to Clip lead cable, unterminated. No attempt was made to keep things short and proper for RF type frequencies, just a quick test to show how the DSO can implement a nice Impedance Plot with the help of the Bode Function. Also didn't change the scope input channels to 200MHz or full BW from 20MHz BW which probably should have done. Also should add, that the DUT "sees" the source 1K Resistor which affects the low frequency response. Best, |
| The Electrician:
I figured there were reasons, related to the likelihood that you hadn't made a major project out of it! :) |
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