Author Topic: Your DER/IET DE-5000, DE-6000, MS5308 has this strange behaviour? (Read 25850 times)

Carrington · « **on:** March 16, 2016, 12:08:35 am »

Hi all!

I was trying to measure some of these thin film inductors (http://data.leocom.kr/datasheets/316338_360095.pdf) with my DER DE-5000.
I wasn't looking for an accurate measuring, but the results don't make any sense. And I know, 100 KHz is not the best (or most appropriate) frequency, to measure these types of inductors. But please, let me continue.

Later I started to thought than maybe have to do with their DC resistance, so I did a little test:

I measured ~ 1cm wire in series with 1 ohm resistor. And I get a reading of ~ 0.15uH (Ls) with 1 OHM (ESR), instead of ~ 10nH (Ls) and 1 OHM (ESR). However if I measure only the wire (without resistor), the DE-5000 show ~ 13nH.

So, what is happening here? What is wrong?

I repeated the test several times, calibration included of course, even I try with short cables for the DUT (see the attached picture at the end). But always I got the same result.

The exact values were:
- Wire: 1.3cm (long), 0.3mm (thick) ie. arround 11.5nH. -> http://chemandy.com/calculators/round-wire-inductance-calculator.htm
- Resistor (thin film): 1 ohm 1% 805 case.

And the final question is:

Do you get similar results with your IET DE-5000, DE-6000 or DER DE-5000?

Several weeks ago (February 3, 2016), I sent an email to the DE-5000 manufacturer, to let him know about this. And guess what, no reply yet, and I'm afraid than ever.

If I'm not wrong the accuracy on the DE-5000 is expressed as an % of rdg. plus x digit, right?
So for a reading of 0.100uH @ 100KHz we have an uncertainty of +-0.0075uH (2.5% +5)
Or IET/DER is expressing the error in another way?

Edited to change the subject title.

Carrington · « **Reply #1 on:** March 16, 2016, 12:12:38 am »

I asked to Thomas (TurboTom), about repeat the previous test with their Applen AT826.
And he, very kindly agreed, here are the results. Thanks again Thomas!

Carrington · « **Reply #2 on:** March 16, 2016, 12:15:00 am »

I also asked to Jake (jaxbird), about the same. Here are the results. Thanks you very much Jake!
Note: Your impedance analyzer is amazing!

Carrington · « **Reply #3 on:** March 16, 2016, 02:42:54 am »

What a coincidence! I just received a message from DER.
I previously expressed my intention to make this problem public here, so seems that they have been waiting for it.

They just asked for serial numbers, supplier and other things, but no explanation about the issue.
Anyway, at least it's a progress, let's see what happens.

D3f1ant · « **Reply #4 on:** March 16, 2016, 03:16:30 am »

Tried this on my Der EE and get similar result, 0.139uH on a 0.4mm wire with a 1R resistor (0603) soldered in series.

Carrington · « **Reply #5 on:** March 16, 2016, 03:21:54 am »

Quote from: D3f1ant on March 16, 2016, 03:16:30 am

Tried this on my Der EE and get similar result, 0.139uH on a 0.4mm wire with a 1R resistor (0603) soldered in series.

Thank you for trying.

I think we have a firmware bug, or maybe something worse.

Quote from: ietlabs on November 07, 2014, 03:13:47 pm

Thanks for all the interest and feedback with the DE-6000
Everyone is correct, the DE-5000 and the DE-6000 use the same components. However, there are two significant technical difference between the two units:

1: Improved accuracy to 0.2% at 1kHz . IET provides an updated firmware to improve on the accuracy of the LCR Meters at 1 kHz.
2. A LabVIEW Driver for is available for collecting data from the DE-6000.

Benjamin Sheena
IET Labs

jarvis · « **Reply #6 on:** March 17, 2016, 02:29:35 am »

I noticed you use one small PCB with wire (2wires or 4wires ?) connected to DUT.
How did you make the open/short calibration? Including the small PCB with wire shorted ?

Carrington · « **Reply #7 on:** March 17, 2016, 02:49:15 am »

@ jarvis:

This PCB is part of the TL-21 fixture, and I used four wires of course.
Maybe a picture is better than an explanation, see attachments.

I can assure you that this "error" (bug or whatever) has nothing to do with the test fixture.

jarvis · « **Reply #8 on:** March 17, 2016, 02:54:27 am »

Dear Carrington

How about the Inductance test result for this 1 ohm resistor only ?

Carrington · « **Reply #9 on:** March 17, 2016, 02:58:30 am »

Quote from: jarvis on March 17, 2016, 02:54:27 am

Dear Carrington

How about the Inductance test result for this 1 ohm resistor only ?

By any chance, do you think that a 0805 smd resistor has an inductance of 140nH!

Carrington · « **Reply #10 on:** March 17, 2016, 03:06:01 am »

Source: http://www.planetanalog.com/document.asp?doc_id=527522

Carrington · « **Reply #11 on:** March 17, 2016, 07:02:51 am »

Ok, the resistor alone:

- First picture, 0 ohm.
- Next picture, 1 ohm.

For both pictures: Unknown tolerance (pick up from a board), 0805 case, and fresh calibration.

0 ohm: all ok, Ls is within the error. (3 counts vs 5).
1 ohm:

(As I expected).

Carrington · « **Reply #12 on:** March 17, 2016, 07:14:09 am »

Carrington · « **Reply #13 on:** March 17, 2016, 07:31:29 am »

However, with higher values of resistance, it could reach perfectly 140nH, and even more.
For example: http://electronix.ru/forum/index.php?act=attach&type=post&id=55596

mos6502 · « **Reply #14 on:** March 17, 2016, 08:05:44 am »

Can you look at the voltage across the resistor with a scope while measuring?

Carrington · « **Reply #15 on:** March 17, 2016, 08:17:10 am »

Quote from: mos6502 on March 17, 2016, 08:05:44 am

Can you look at the voltage across the resistor with a scope while measuring?

Yes, I can, but later, now I can not.
But the probe will affect the measurement.

No one can make this simple test with their DE-5000/6000?

mos6502 · « **Reply #16 on:** March 17, 2016, 08:49:14 am »

Relax bro, I'll do it, later.

What's the revision number of your DE-5000?

rosbuitre · « **Reply #17 on:** March 17, 2016, 09:15:30 am »

Hi
I get tired of sending mails to the manufacturer, asking for new software / firmware and never responded, 0 post sales service

Regards

Carrington · « **Reply #18 on:** March 17, 2016, 09:37:09 am »

Quote from: mos6502 on March 17, 2016, 08:49:14 am

Relax bro, I'll do it, later.

What's the revision number of your DE-5000?

Sorry, I'm a little stressed.
Here you have, but, what are you looking for?

Carrington · « **Reply #19 on:** March 17, 2016, 09:43:25 am »

Quote from: rosbuitre on March 17, 2016, 09:15:30 am

Hi
I get tired of sending mails to the manufacturer, asking for new software / firmware and never responded, 0 post sales service

Regards

Yeah, this type of situations can be a bit irritating.
I didn't even expect an answer. The funny thing is the beginning of their email: "We try to solve your problem soon".
I hope they don't need another half month to reply again.

mos6502 · « **Reply #20 on:** March 17, 2016, 09:46:59 am »

Quote from: Carrington on March 17, 2016, 09:37:09 am

Quote from: mos6502 on March 17, 2016, 08:49:14 am
Relax bro, I'll do it, later.

What's the revision number of your DE-5000?
Sorry, I'm a little stressed.
Here you have, but, what are you looking for?

I don't know ... maybe resonance or something? If the signal is clean, it's probably a software issue.

I did a quick test, 1 ohm resistor, shortening the leads by 20mm (10mm each side) reduces the inductance by 53nH. My meter is version 8.

mos6502 · « **Reply #21 on:** March 17, 2016, 09:57:36 am »

Woops, another interesting discovery: with the longer leads, the 1 ohm resistor measures as 17uF, shorten the leads by 20mm and capacitance is OL.

Carrington · « **Reply #22 on:** March 17, 2016, 10:00:15 am »

Thank you very much!

About the revision: I never take it apart, so no idea.

And from your the results, I think we have more of the same.

However, this damn thing has no problem with capacitors. Anyway!

Thanks again.

Carrington · « **Reply #23 on:** March 17, 2016, 10:02:22 am »

Quote from: mos6502 on March 17, 2016, 09:57:36 am

Woops, another interesting discovery: with the longer leads, the 1 ohm resistor measures as 17uF, shorten the leads by 20mm and capacitance is OL.

Oh, my God! Nobody has noticed all this before? Weird!

Edit 1:

But wait that's Cs. Have you checked Cp?
142nF on mine for the 1 Ohm resistor.

Edit 2:

And for the "deree5.jpg", I think that probably you have a short.

Carrington · « **Reply #24 on:** March 17, 2016, 10:11:43 am »

Same revision here.

I'm dying to see the results of an EIT!


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