pc motherboard grounds

WHERE did you SHOW a WORKING circuit ?? You didn't.

I design sub-nanosecond stuff on-chip all the time, so shove your snarky crap up your ass.

You're a shit "designer"... all NO-SHOW. ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.

This isn't about screws, idiot. It is about industry wide and fully adopted and accepted circuit board design standards.

You are a goddamned retard, Williams.

Except that a PROPER installation of ANY mobo into ANY case, even back then, involved at least ONE tie point of the MOBO to ground, and that was usually via a single hard stud/standoff.

There NEVER was ANY proper mobo installations that was made full floating by the dumbass installer using plastic at every point.

Even if a PhD did it, it was a failed assembly. It requires at least ONE tie to the chassis. That has ALWAYS been true. FOREVER! PERIOD!

PC/104 is NOT the PC spec. That is an entirely different form factor/bus/architexture altogether.

That is because the spec allows several different vendor devices to end up on your backplane, dingledorf.

They are also hot swap capable.

Again, it is an entirely different concept than a PC is.

Are you so dumb as to think that emissions testing would pass without it back in the TTL early CMOS days? They were far more emissive then than now.

In order to comply with the FCC emissions standards, intelligent designers in the PC industry ALL tied their ground planes to their mobo/chassis mounting holes.

You guys all lost some basic common sense somewhere along the way.

Amazing. Back in the TTL and early CMOS daze, presumably the 1970's, there was S-100, Multibus, DEC Unibus, and such. They radiated badly, mostly because of the long unterminated wire lengths. (Wires make good antennas, components do not). However, as computahs progressed, and technology improved, the bus lengths shrank, as did the number of components that needed interconnection, thus reducing radiated EMI somewhat. However, at the same time, the power consumption of the CPU started climbing. Today, Intel CPU's are hovering around 75-100 watts. Tricky methods, such as "spread spectrum" clocks really didn't reduce the radiation as much as it took advantage of a stupid loophole in the FCC part 15 specifications. You have only to turn on a 2-way radio in a room full of computers to test the effectiveness of the current EMI/RFI reduction efforts. I would say that it's about the same as the 1970's with the added bonus of having to deal with more EMI/RFI producing devices.

Also amazing. We had a simple test to determine if the PCB was properly bypassed. We would fire up a spectrum analyzer with a small discone or biconical antenna, and put it near the board. If attaching it to the base plate (usually a piece of aluminum sheet metal with PEM standoffs installed) had any effect on the radiated RFI, there was a problem. Only when mounting and grounding the board to the baseplate were we sure that there were no circulating currents going through the sheet metal, which would eventually act as an antenna in the final product. Relying on the case for grounding is not a great idea.

I prefer a balanced sense as in a Kelvin bridge. Common (ground) sense measurements are inaccurate.

--
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
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Cite these "standards", AlwaysWrong.

*Everyone* here knows you're AlwaysWrong.

Cite the specification that requires it, AlwaysWrong, or admit that you're just making it up as you go.

Cite the specification that requires this.

You never had any, AlwaysWrong. Of course, the janitor, and village idiot, don't need any sense at all. I suppose we all have our places in the orgainization. Someone has to keep the pipes clear.

Irrelevant, AlwaysWrong.

Completely irrelevant, DimBulb.

Moving goal posts again, Dimmie?

surrounding a hole was always (?) connected to ground. OTOH other copper foil running right next to the hole isn't always ground, and I've measured 5V and

3.3V on some; in one case the copper on the left side of the hole was connected to the 5V supply and the copper on the right went the 3.3V (FIC brand PA-2007 or VA-503+ motherboard)

We had a problem with plated holes, where they couldn't keep the tolerance on the holes in spec for the mounting tabs. We had to have the plating removed.

The extra vias seem to be a good idea, though. There's no cost, so...

Sooth Sayer is probably another sock puppet for Always Wrong. You can change your handle, but the asshole stench always comes through.

No, you are.

The machine screws and standoffs come with the case.

if they wanted the hole insulated ther's just design the PCB with no electrical connection to the holes.

I've seem a few cases that used a combination of plastic ans metal standoffs, not so mant recently. Some standffs have 6-32 thread others have M3, some have one end 6-32 and M3 at the other.

On the board I measured all the bolt holes were connected to ground.

--
?? 100% natural

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I've posted a bunch of current source circuits. They all work.

So show something of your own.

You can't.

--

John Larkin                  Highland Technology Inc
www.highlandtechnology.com   jlarkin at highlandtechnology dot com   

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME  analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators

USB, PCIe, SAS, and SATA are all hot swappable, also all the external connectors (I've never had trouble hot swapping PS/2 peripherals despite what the rules say)

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?? 100% natural

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No 'probably' to it:

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No shit. Peripheral connection is yet one more reason why there will ALWAYS be a connection between the MOBO ground and the case and the shells of all of those peripheral interconnects you speak of.

So, nothing has changed idiot. Hooking up a USB cable to a "ground-make-first" connection is entirely different than hooking up a PC/104 device into a back plane. There are only about 100 more connections being made.

And no, idiot, SATA was NOT hot swappable SAS is OOTB, and eSATA is, but SATA is NOT.

To use SATA as a hot swap, there has to be a device (drive controller/hot swap bay, etc.) in between the device and the computer's SATA port.

[snip]

In previous posts you said that the ones you attempted for your 1V/ns ramp oscillated??

Show us the ramp device that _doesn't_ oscillate.

And learn how to appropriately snip. Or is your whole object to see your name constantly in print ?:-) ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.

Me thinks so.