HOME  |  NEWS  |  BLOGS  |  MESSAGES  |  FEATURES  |  VIDEOS  |  WEBINARS  |  INDUSTRIES  |  FOCUS ON FUNDAMENTALS
  |  REGISTER  |  LOGIN  |  HELP
vimalkumarp
User Rank
Gold
six wire technique
vimalkumarp   11/26/2011 10:59:11 AM
NO RATINGS
This is very useful idea for ICT development.

 

William K.
User Rank
Gold
Six wire technique nulls stray resistance
William K.   11/17/2011 10:51:04 PM
NO RATINGS
A whole bunch of years ago I designed and improved system for checking the fuel injection system s tverify that all 4 of the 1.2 ohm injectors were connected.  I replaced a resistance measuring systemthat had problems with one that used a constant current source. Because the injectors were relatively high power devices I was allowed to run 100Ma through the harness as part of the test. I used a constant current regulated source, and so the connected harness assembly yielded 100 millivolts per ohm, entirely adequate resolution. My application only required four wires to provide the needed accuracy. It worked well and saved our company a lot of money, and it made our customer happy as well. On top of that, it gave us a very short product lead time. 

GotCMRR
User Rank
Iron
Clever technique
GotCMRR   11/16/2011 9:35:28 AM
NO RATINGS
Simple & elegant.  Just watch your OpAmp's feedback polarity.  Your schematic as drawn doesn't work ;)

Beth Stackpole
User Rank
Blogger
Re: More complexity, more work?
Beth Stackpole   11/15/2011 11:05:50 AM
NO RATINGS
Got it. Thanks for clarifying, Jon.

Jon Titus
User Rank
Blogger
Re: More complexity, more work?
Jon Titus   11/15/2011 10:40:22 AM
NO RATINGS
Hi, Beth.

If you have a resistance (A)  in a network of other resistances, Ohm's Law dictates the resistance you would measure directly across resistance A.  To accurately measure resistance A by itself, you either isolate it from the circuit (removing it would do the job) or electrically null the other resistances so no current flows through them.  That's what the 6-wire technique does.  Automatic test equipment (ATE) uses a similar technique to electrically isolate resistances.  By the way, a similar technique would for capacitances, too.

The need to electrically isolate components does require extra test equipment, but the 6-wire technique offers the only practical way to make accurate in-circuit resistance or capacitance measurements.--Jon

Beth Stackpole
User Rank
Blogger
More complexity, more work?
Beth Stackpole   11/15/2011 6:40:16 AM
NO RATINGS
So if I understand it correctly, this six-wire technique works best when there's a network of resistors and you're challenged with measuring the resistance of only one? It also makes sense when measuring resistance with test equipment because of the possible interferences by dirt, grim, etc.? I'm wondering how much more difficult this technique is compared with standard practices?

 

 



Partner Zone
Latest Analysis
A study by the Swiss government determined the type of human errors that lead to engineering disasters and ranked those errors by percentage.
General Motorsí growing commitment to electric cars took a new turn last week, as the giant automaker said it would use EV batteries in the future to help boost its use of renewable energy.
A fabric designer and chemical engineer have teamed up to design fabric woven with solar panels for the future of wearable, autonomously powered technology.
A new linear encoder will offer measurement resolution of about 31 picometers -- less than the diameter of an atom -- when it hits the market in prototype form later this year.
Apple made some controversial decisions with its new iPhone 7 models, so what did they do with the extra space? The latest teardown from iFixit digs under the hood of Apple's new sensor-heavy phone.
More:Blogs|News
Quick Poll
The Continuing Education Center offers engineers an entirely new way to get the education they need to formulate next-generation solutions.
Sep 12 - 16, Analytics for the IoT: A Deep Dive into Algorithms
SEMESTERS: 1  |  2  |  3  |  4  |  5  |  6 |  7 | 8 | 9 | 10


Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.
Next Course June 28-30:
Sponsored by Stratasys
Learn More   |   Login   |   Archived Classes
Twitter Feed
Design News Twitter Feed
Like Us on Facebook

Technology Marketplace

Copyright © 2016 UBM Canon, A UBM company, All rights reserved. Privacy Policy | Terms of Service