4-Layer boards

Yeah, It's this case I'm thinking about. But, I've got a model now... breaking up the ground into current filaments... not high enough frequency for top and bottom to disconnect. (Still, as I draw pictures.. Think Faraday and field lines, I get lower energy, by confining the fields.) see below at DC...

Is that true if we're talking about a plane conductor, vs a solid? For a 2-D thing like a ground plane there should be a different relation... longer I'd guess... 1/f?

George H.

Oh Snap, I wanted to say it's this transition, from DC "star ground" to RF ground plane that interests me the most. I've got one data point that says RF is >1MHz, maybe even 100kHz. GH

For an infinite block of ground "plane", of course it's any frequency (it goes deeper and deeper as you approach DC, but lim-->0 isn't zero-zero).

True, edge effect could be a different function, because the geometry is different (it's got... more sides?). I don't think the units will work out any other way than diffusion though.

Exercise for the student: solve the field equations for foil. :^)

Tim

Interesting and related fact: copper traces make s***ty shunt resistors, because they're primarily inductive above ~10kHz, making them wholly useless for SMPS. (And anyway, the tempco is as bad as Rds(on) of a FET, so who cares.)

Tim

Agree about tempco, but a copper trace might have a few milliohms of resistance and a few nH of inductance, which should be usable. A surface-mount milliohm resistor will have more inductance than a trace of the same footprint.

A downstream RC will flatten out either.

What does it mean "to read squat"? Google isn't very helpful here.

Best regards, Piotr

basically means they don't even look at it

dictionary says: squat = Slang, A small or worthless amount

-Lasse

That's a bit euphemistic. While not actually obscene, it isn't a polite exp ression, as you'll have gathered from the context. ;)

Cheers

Phil Hobbs

Den fredag den 15. april 2016 kl. 13.11.55 UTC+2 skrev Phil Hobbs:

xpression, as you'll have gathered from the context. ;)

yeh, I guess in most uses it is a replacement for "s*it"

-Lasse

Hi Oppie. I found what you worked in air pollution research. How can I contact with you? I'm trying to build pollen detection devic and need for some advice. Sorry for off topic.