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
Former DARPA official and Google executive Dr. Kaigham Gabriel believes sensor companies think too much like suppliers and need to bring their products closer to the consumer.
One way to keep a Formula One racing team moving at breakneck speed in the pit and at the test facility is to bring CAD drawings of the racing vehicleís parts down to the test facility and even out to the track.
Most of us would just as soon step on a cockroach rather than study it, but thatís just what researchers at UC Berkeley did in the pursuit of building small, nimble robots suitable for disaster-recovery and search-and-rescue missions.
Engineers at Festo were inspired by how a caterpillar builds its cocoon when designing its new 3D Cocooner printer.
Design engineers need to prepare for a future in which their electronic products will use not just one or two, but possibly many user interfaces that involve touch, vision, gestures, and even eye movements.
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


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