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
Platinum
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
Following in the tracks of the fabled rocket plane programs of the 1940s, NASA engineers are now laying the plans for a new twist on the future of aviation -- a battery-powered airplane.
Laser engravers can be great tools for DIY projects. But they can also be pricey. Gadget Freak shows you how to build your own CNC laser engraver using an Arduino board.
Your home could someday be filled with hundreds of connected devices. What's going to coordinate it all? According to iRobot, it could be a vacuum with machine vision.
Researchers at the University of Buffalo have developed a nanocavity to potentially improve the design of ultrathin solar panels, video cameras, and other optoelectronic devices.
The Industrial Internet of Things may be going off the deep end in connecting everything on the plant floor. Some machines, bearings, or conveyors simply donít need to be monitored -- even if they can be.
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.
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 Proto Labs
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