Why are they called "resistors"

Oh, I've been using the SLIM MOX series from ohmite. They've got a nice blue coating.

George H.

He certainly didn't design it. He may have potted it.

John

It matters not what the surface is made of. It IS a surface!

THAT is what gets electron flows across it.

LV should be fairly stable, but I would still seal it after it becomes a cleaned assembly

Never handle except with gloves. Not the package, and NOT the leads as well.

You're a goddamned liar.

Imeasured your mental fallacy toady with 100% accuracy.

I perform math every day. You likely do not even know what the term "link budget" means.

Show me somewhere where I needed to.

Sure I do. Just today I was telling some dope that high value resistors are problematic when the user fat fingers them. That is absolutely an industry fact.

Contaminants modify performance of high value resistors.

The industry has proven it, John. I do not need to.

No. I said that they are hard to get in SMD, but then, I haven't tried in a while. We have a pretty good parts inventory. I'd bet there are values in there I haven't used since the HV days.

Getting a reading on one is easy. Getting an exact, reliable reading on one can be a bit more elusive. What you do is assume that what you read is what you have. That is not always the case.

Absolutely so.

That is why if you have a multiplier failure, it is cheaper to replace the entire set than it is to attempt to locate the failed segment.

Up to a point, of course. The problem is locating the failed part.

The labor lost in diagnostics is more costly than the parts and the swap time, so the whole thing gets swapped.

Upon examination of the removed parts, one has problems finding the failed cap, HOWEVER, the circuit now works just fine.

This is because most HV cap failures are of the "punch through" type.

Work fine at LV, but "leaks" as the potential rises above the arc over point within the insulator layer at the "hole" site.

I made simulator racks for the C-17 Heads Up displays.

Two slides in Delrin, and a peg board where any shorts or opens could be "simulated", so that they (McD D pre-Boeing) could test the redundancy mode compliance, and watch it kick in, and attempt to drive it (short it) to failure. That was years ago.

Currently, I put satellite connectivity into C-17s

A lot of the gear is BAE's so we get some of their stuff, put some of ours in it, and sell it at a premium. Nothing new.

The question is... do you TOUCH them?

You're an idiot. You bounce back and forth between insults and actually acting like you want to learn something. He may have potted it.

HV is easy. I have several designs. LANL and LLNL like me a lot.

So does the NOAA. We used to send them three. They would beat the hell out of all three, and REALLY beat the hell out of one, and one would end up in a high altitude balloon experiment requiring an HV source. It is a common experiment. These days, they might even use some kind of high altitude glider and actually get the gear back!

It means you don't have numbers.

John

That's the type I posted the Keithley picture of, nice shiny blue epoxy. Fingerprints made no measurable difference at 1G ohms.

John

That doesn't make any sense - why not the leads?

Are you saying that Ohmite doesn't know what they are talking about? Much less the entire remainder of the industry?

"no measurable difference" means that John doesn't know how or where to look for "the numbers" he is so hep on hearing.

It should have read "Mo measurable difference utilizing John Larkin's limited real world understanding and knowledge of test conditions and equipment."

No, you incompetent twit. YOU don't make any sense. Particualarly since instead of reading and actually following a thread , you look for a post which you can make your petty, uninformed pussy boy jabs at.

Had you paid attention and were you actually reading the thread, you would already know the answer to that dumb question.

I'm saying that I made my own measurements, and posted the numbers.

"hep"? Wow, I haven't heard that word in a long, long time.

Word salad again. Why don't you do some measurements and tell us what you get?

John

The glass resistor link said to handle them by the leads:

"These resistors should be handled by the leads, unless gloves are worn."

John

OK I just sent the 10nA (from 10V ref and 1G resistor) through a

George H.

Oh sorry I missed the pic. Yeah I just tried to get mine to leak from finger prints.... no luck. Breathing on it made a big difference. I wonder if it would be worse in the summer with more moisture in the air?

George H.

These high-ohm resistors tend to have bad TCs, so the slow drift may be temperature.

Heavy breathing can cause condensation, and that will conduct big-time. I don't see any change from modest breath-blasts, which presumably increase humidity but don't cause condensation. Of course, humidity may be a long-time-constant effect. But the bottom line is that 1G ohms isn't hard to work with.

Our biggest leakage problem is the occasional ionic contamination under surface-mount parts from water soluble flux and inadequate water washing. That leaves hygroscopic crud. In house, we use rosin flux and organic cleaning, and never have leakage problems. It's only the rare case when we send assembly out and the assembler messes up, usually dirty wash water or inadequate spraying; we don't use them again. I think there must be lots of assemblers who do mostly digital or consumer stuff, where nA leakage doesn't matter, and don't get feedback on their cleaning quality.

John

What does "make a rack" involve?

John