EE Times Suicide

It isn't correct. Even at DC, charge density couples to the Laplacian of the potential, not the potential itself, and at AC you have EM waves to worry about.

A few counterexamples:

DC: The inside of the sphere of an operating van de Graaf generator can be at +-20 MV, with little or no free charge on the interior surface. There's certainly a voltage present there!

AC: The E field strength 10 metres in front of a radar antenna is enough to mess up just about any electronic device, yet there are no free charges there.

Higher frequency AC: A focused laser beam.

Cheers

Phil Hobbs

also gmail ignores capitalisation of the entire address giving you several bits to flip, in addition (on gmail) you can insert single dots into the mailbox part and they are ignored too, domains are case insensitive to twiddling caps in the domain part won't hurt routing.

snipped-for-privacy@gmAIl.coM

these binary patterns are less mnemonic than +foo but should be universally applicable.

well, you're pointing to some area where there is no charge, but the field is defined over entire R3 and the field in the area you are discussing originated from a charge, possibly moving charge, somewhere else.

The author of the piece clearly knows zero electromagnetics. I agree with what you said just above, but (a) that isn't what the author said, and (b) neither is very useful for understanding how to get rid of pickup and ground loops.

Morrison is the go-to reference for that stuff. (NOT HoJo.)

Cheers

Phil Hobbs

Morrison? Got a link somewhere?

Sometimes it would be good to be able to point clients to a good book or web publication. "Trilogy of Magnetics" from Wuerth Electronics is a really good book in that domain (with some minor reservations, as usual). I think it's around $50 which would be very well invested money for a newcomer. I've got it here on loan from Wuerth right now but only for review, will give it back some day because I am "past that age".

I'm amazed.

Jeroen Belleman

Ralph Morrison, Grounding and Shielding Techniques, Fourth edition, Wiley, 1998.

Cheers

Phil Hobbs

I thought the Wurth book was really lame. Two Wurth sales guys called on me. One pushed me to buy the book as the other one made faces and rolled his eyes.

Thanks, Phil. I bookmarked that and will check it out, could be useful for folks learning this stuff.

Well, I learned this stuff by doing, not via books. The first book I bought about it was HoJo's but only because I needed something where I could say "Look at page xxx figure xx". Not because I needed it. That book is ok but not 100% IMHO.

It's the same with Radar, eventually I gave my Radar Handbook to our library because I kind of knew the stuff from it that I needed. No point in hanging on to something I rarely use but where the next kid with maybe not a lot of financial resources could learn from. Of course, then I realized I had no more cheat sheet to gauge sideband leakage versus Hilbert phase errors. It's in that book.

One

They didn't push me to buy it, just to take a look. They'll pick it up on the next visit. It may be lame to you and me but can help a newcomer a lot. For example, they often don't have the foggiest how loops form and how they can couple with stuff from elsewhere. Universities often don't teach this anymore.

One

You can have mine.

John

One

You bought it?