In part one of this post, I noted that there are three primary EMC coupling problems that are associated with the green wire safety ground: 1. The green wire conducted noise current modulates the signal and shows up as a differential voltage change across the load.2. The green wire forms a pick-up loop and acts like a magnetic field antenna.3. The green wire loop acts as a … [Read more...]
They’re Everywhere, They’re Everywhere – Part I
Read Part II here.I just finished rearranging my office. It all started with buying a new MS Windows 8 computer (that’s a story all on its own) followed closely by the failure of my printer to feed paper. So I bought a new printer, which is about two times bigger than my old one, and it wouldn’t fit in the previous location. So I moved my little flat screen TV into the old … [Read more...]
Zap – You’re Gone! A Few Truths About Lightning Safety
The last several posts have been about EM radiation hazards (RADHAZ), but there are other electromagnetic hazards. If you’ve ever been shocked by an ESD jumping from your finger to a doorknob after walking across the carpet on a cold dry winters day just imagine that incident being magnified by multiple orders of magnitude. I live in Florida and we are now winding … [Read more...]
Do We Only Believe Things that Match Our Opinion?
Whoopee! I finally got some feedback that people actually read some of the stuff I write. I received several great comments about a previous post titled: Electromagnetic Fields Don’t Exist. I’m not sure they liked what I had to say, but most were nice about it. I apparently excited some nerves. That happens when they’re exposed to electromagnetic radiation. I’m using … [Read more...]
I Can’t Believe I Just Cooked My Pinna
In the previous post, I was discussing cellphone RF safety and the fact that we really don’t know what level is safe and what’s not. Those individuals that go around with a cell phone or Bluetooth device glued to the side of their head will be happy to know that the FDA and the FCC are concerned about cell phones cooking their outer ear (the pinna). They have apparently … [Read more...]
Electromagnetic Fields Don’t Exist!
Some time ago, I made a big to-do about smart electric meters and the fact that they might be hazardous to our health. The general response I got was: you got to be kidding. Sometimes from the more heavily invested the response is: there is insufficient evidence to make that conclusion. The World Health Organization concluded that electromagnetic fields from cell phones and … [Read more...]
Growling in Hi-fi and Stereo
In the last couple of posts I’ve been discussing ground loops and bonding and I made a comment that at the higher frequencies, i.e. VHF/UHF and higher multiple point grounding is used. It occurs at these higher frequencies because of capacitive coupling whether we planned it that way or not. The so-called ground loop exists whenever there are multiple ground connections … [Read more...]
Togetherness is Another Way of Saying Well Bonded
Electromagnetic compatibility (EMC) is often described in terms of RF coupling phenomena. Usually the big four: Radiated and Conducted Emission and Radiated and Conducted Susceptibility/Immunity. These four elements cover all of the EMC issues in a very broad sense. Occasionally lightning and ESD will be divorced from susceptibility and described as if these two items were … [Read more...]
The Ground Loop
Several readers have made comments regarding multipoint grounding (MPG) systems. The concern is that this arrangement creates multiple ground loops. As a result, we need to address that. As some of you know, I make a lot of presentations and teach a lot of EMC seminars. A long, long time ago, I was discussing ground loops in one of my training classes … [Read more...]
Can an Ordinary Human Stop RF Noise?
When my son was working on his EE degree he found an article titled: Stop That Noise in the IEEE Potentials, October - November 1995. Being a dutiful son, he brought it home to his EMC-dad and I read it. It is a great little article giving an overview of the cause and effect of EMC problems. The articles primary thrust is to introduce EMC to college students and encourage them … [Read more...]
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