HOME  |  NEWS  |  BLOGS  |  MESSAGES  |  FEATURES  |  VIDEOS  |  WEBINARS  |  INDUSTRIES  |  FOCUS ON FUNDAMENTALS
  |  REGISTER  |  LOGIN  |  HELP
Tool_maker
User Rank
Platinum
Duplicating Problem
Tool_maker   10/24/2012 12:57:38 PM
NO RATINGS
  Your story demonstrates one of the keys to trouble shooting many problems: Being able to duplicate the failure. So many times there is a problem that appears randomly and until I can find out why, I am never totally satisfied with the fix. Even if it is my own error, just correcting it without knowing the thought process that caused the error to begin with drives me crazy.

notarboca
User Rank
Gold
Re: Surge impedance
notarboca   10/17/2012 9:20:46 PM
NO RATINGS
DanSchwartz, you included a lot of knowledge in your post; I learned a lot.  Thanks for the post!

DanSchwartz
User Rank
Iron
Surge impedance
DanSchwartz   10/12/2012 10:40:41 AM
NO RATINGS
It's called surge impedance Zo, which is defined as √(L/C), where L is the inductance in Henrys, and C is the capacitance, which for a coil is the interwinding stray capacitance.

The back EMF V= ZO(∂I/∂T), and it will have an oscillation frequency 1/(2π√LC). When you open up contacts in an inductive load, ∂I/∂T goes to ∞: You see this as an arc when you unplug an iron; and also when relay & motor starter contacts are switching off an inductive load.

This is also why contactors have serious current deratings when switching off DC: Once the arc is established and current flows through the ionized channel, there is no zero crossing to extinguish the arc, as occurs with AC,

When dealing with AC, you design using the peak (not RMS) value of the load current when calculating, because you don't know where in the AC cycle the contacts will open.

Note: Those of you who are RF jocks will quickly recognize ZO = √(L/C) as the equation for the characteristic impedance of a transmission line: Yes, it's the same thing.

Dan Schwartz,
Editor, The Hearing Blog

John E
User Rank
Silver
Re: Old and new
John E   10/11/2012 11:40:55 AM
NO RATINGS
We had changed the output driver from a completely analog design, to one with a digitally controlled output driver.  The new driver would reset occasionally with the noise or the communications to it would get interrupted.

On the old module the noise would pass through to the output, but the frequencies were well above the system response time.

naperlou
User Rank
Blogger
Old and new
naperlou   10/11/2012 10:34:30 AM
NO RATINGS
John, did you guys compare the old and new analog modules that you had designed?  It would be interesting to know what the design engineer changed between the two.



Partner Zone
Latest Analysis
This Gadget Freak review looks at a cooler that is essentially a party on wheels with a built-in blender, Bluetooth speaker, and USB charger. We also look at a sustainable, rotating wireless smartphone charger.
Texas Instruments is rolling out a new microcontroller that could make the design of sensor networks and data logging systems simpler and less costly.
Made By Monkeys highlights products that somehow slipped by the QC cops.
From pitchers and forwards to quarterbacks and defensemen, we offer a peek at some of the more memorable engineers in sports history.
IBM announced it is dedicating $3 billion of funding over the next five years to research and development of new processor technologies.
More:Blogs|News
Design News Webinar Series
7/23/2014 11:00 a.m. California / 2:00 p.m. New York
7/17/2014 11:00 a.m. California / 2:00 p.m. New York
6/25/2014 11:00 a.m. California / 2:00 p.m. New York
5/13/2014 10:00 a.m. California / 1:00 p.m. New York / 6:00 p.m. London
Quick Poll
The Continuing Education Center offers engineers an entirely new way to get the education they need to formulate next-generation solutions.
Jul 21 - 25, Design Products With Bluetooth Low Energy
SEMESTERS: 1  |  2  |  3  |  4  |  5  |  6


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 Class: August 12 - 14
Sponsored by igus
Learn More   |   Login   |   Archived Classes
Twitter Feed
Design News Twitter Feed
Like Us on Facebook

Sponsored Content

Technology Marketplace

Copyright © 2014 UBM Canon, A UBM company, All rights reserved. Privacy Policy | Terms of Service