Breaking News
Comments
Oldest First | Newest First | Threaded View
chcuk
User Rank
Rookie
re: Electrical noise and mitigation - Part 2: Ground loops, noise transmission and shielding
chcuk   12/24/2008 2:50:11 AM
NO RATINGS
It is very good and comprehensive. But it seems to me that we need have a different approach for electrostatic or magnetic problem. Sometimes they are even against each other. The point is what is the scenario of which, electrostatic or magnetic play more dominant role.

Guru of Grounding
User Rank
Rookie
re: Electrical noise and mitigation - Part 2: Ground loops, noise transmission and shielding
Guru of Grounding   9/3/2010 5:21:56 AM
NO RATINGS
I fail to see how the circuit in Figure 8.19 is "balanced". When one of the signal lines is grounded, the interface is unbalanced by definition. Also, anyone who believes that two conductors in a shielded cable have equal capacitance to the shield is a fool! If the wires are different colors (no joke), their capacitances can easily differ by 5% or more. I've measured this myself on many commercial cables (try Belden 8451, for example). Bill Whitlock, president & chief engineer of Jensen Transformers www.jensen-transformers.com and Fellow of the Audio Engineering Society

Guru of Grounding
User Rank
Rookie
re: Electrical noise and mitigation - Part 2: Ground loops, noise transmission and shielding
Guru of Grounding   9/3/2010 7:13:18 PM
NO RATINGS
What I was told by Belden (and it makes perfect sense) is that different color wires must have insulation applied by different extruders (where liquid PVC coats bare wire pulled through a small die). The tolerances on the die, and therefore, insulation thickness can vary by .001". Using 8451 as an example, this makes capacitance change by about 5%. However, by grounding a (balanced interface) cable shield only at the source end, most of the CMRR-degrading effects of the capacitance imbalance disappear. My generic seminar (see http://www.jensen-transformers.com/an/generic%20seminar.pdf) explains in detail.



EE Life
Frankenstein's Fix, Teardowns, Sideshows, Design Contests, Reader Content & More
Max Maxfield

Steve Wozniak Reacts to Latest iPhone
Max Maxfield
8 comments
Funnily enough, just a few days ago as I pen these words, I was chatting with my wife (Gina the Gorgeous) when she informed me that -- as a kid -- she had never played at making a ...

EDN Staff

11 Summer Vacation Spots for Engineers
EDN Staff
20 comments
This collection of places from technology history, museums, and modern marvels is a roadmap for an engineering adventure that will take you around the world. Here are just a few spots ...

Glen Chenier

Engineers Solve Analog/Digital Problem, Invent Creative Expletives
Glen Chenier
15 comments
- An analog engineer and a digital engineer join forces, use their respective skills, and pull a few bunnies out of a hat to troubleshoot a system with which they are completely ...

Larry Desjardin

Engineers Should Study Finance: 5 Reasons Why
Larry Desjardin
46 comments
I'm a big proponent of engineers learning financial basics. Why? Because engineers are making decisions all the time, in multiple ways. Having a good financial understanding guides these ...

Flash Poll
Top Comments of the Week
Like Us on Facebook
EE Times on Twitter
EE Times Twitter Feed

Datasheets.com Parts Search

185 million searchable parts
(please enter a part number or hit search to begin)