IET DE500: How does 4 wire Kelvin measuring work? - Page 1
Forum section: electronics / testgear

author: Steve Zarg
author_rank: Contributor
timestamp: June 21, 2014, 01:46:21 am
content: I've been looking at the IET DE 5000 LCR meter package and I can't quite figure out how the 4 wire Kelvin measurement feature works with out 4 connections on the handheld unit.Is it really a 4 wire system or is there a "gotcha" that I should know about before I consider this as a feature when comparing the IET DE-5000 with other choices?Thank you.

author: DJ
author_rank: Unknown
timestamp: June 21, 2014, 01:59:06 am
content: http://www.ietlabs.com/de5000-lcr-meter.htmlLooks like the adapter box picks up the source and measure leads from the component slot (4contacts, one above and below each lead) and ties them together at the alligator clip.Delighted to see my beloved 1689 digibridge is still in production from that outfit!

author: georges80
author_rank: Frequent Contributor
timestamp: June 21, 2014, 02:06:11 am
content: Yes, the 'blades' of the adapter units (independent sides of the adapter blades) do the 4 wire 'magic'. Buy the adapters you need when you purchase the unit. The sense wires connect at the clip ends to negate the test lead resistance.Though the DER EE 'version' is cheaper... I bought my unit on ebay from a seller in Japan (about US$120 with 2 of the adapters that I wanted).cheers,george.

author: Steve Zarg
author_rank: Contributor
timestamp: June 21, 2014, 02:15:35 am
content: Thanks for explaining about the blades. That's pretty clever.It's pretty hard not to notice the DER version of the DE-5000.Has anyone every compared the IET to DER side by side to see if they are the exact same unit, or if they are two extremely similar looking units made at the same OEM factory?Thank you.

author: PedroDaGr8
author_rank: Super Contributor
timestamp: June 21, 2014, 02:41:28 am
content: Quote from: Steve Zarg on June 21, 2014, 02:15:35 amThe accepted viewpoint is that Der EE is the OEM for IET.Edit: some have taken them apart. While the revision letters were different they are close enough to say they were from the same company.

author: Steve Zarg
author_rank: Contributor
timestamp: June 21, 2014, 02:48:40 pm
content: Thanks for the info.It seemed to me that it is well known that they are from the same factory, but what I had yet to find specific info about is if they use the same "guts" and have the same performance.Also, the idea that a made in Taiwan product is being sold by Chinese vendors to USA customers on ebay seems to trigger my suspicion that some of the units labeled as DER may be coming from somewhere on the mainland.If I go with one I'll want to find a Taiwanese or Japanese vendor.Does anyone have any links to a side by side comparison?

author: robrenz
author_rank: Super Contributor
timestamp: June 21, 2014, 08:49:37 pm
content: The banana jacks of the DE-5000 are also 4 wire with each jack having 2 separate connections similar to the Fluke 884XA 2x4 connections. But the split in the jacks on the DE-5000 is 90 degrees off from the Fluke so you cant use the Fluke 2X4 kelvin probes in the DE-5000. I have not seen any diy dual split jacks available. The adapters that go into the component test slots work fine so not much point in trying to find the jacks.

author: torr032
author_rank: Regular Contributor
timestamp: June 21, 2014, 09:06:23 pm
content: DER EE DE-5000 units on the ebay are all as I can see coming from Japan. I am not able to find units that cheap on the chinese taobao.

author: Steve Zarg
author_rank: Contributor
timestamp: June 21, 2014, 09:58:12 pm
content: Quote from: robrenz on June 21, 2014, 08:49:37 pmThanks very much for explaining this.

author: Dave
author_rank: Super Contributor
timestamp: June 21, 2014, 10:28:53 pm
content: ThereIS4-wire measurement.Check out the EEVblog episode where he reviews the IET DE-5000 (same meter). You will see the two long slots each have two metal clips that are separately connected to the measurement circuit. One is force, other is sense. The tweezer and crocodile adapters only join the two at the tip of the tweezers / bottom of crocodile clips.

author: radioFlash
author_rank: Regular Contributor
timestamp: June 21, 2014, 10:34:37 pm
content: As Steve Zarg indicated, yes, there is 4 wire measurement. If you open the TL-21, you will see the separate connections for force and sense wires. The TL-21 connections were very short, so I used some cheap ebay kelvin clips and made my own. When I first tried it out the new cables, the self calibration failed, so I had to shorten them.