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Re: gEDA-user: Design Lab Equipment


On Mar 31, 2007, at 12:57 PM, John Griessen wrote:

Steven Michalske wrote:

Plating is important to prevent corrosion. It is required. Un- plated vs plated is not going to make a positive performance impact.
I could talk about thermoelectric effects all day, i'll stop for now.

I read an article about sub 1 PPM measurements where they preferred reasonably uncorroded copper to any plating.

sub 1PPM so nano volt measurements. That's pretty tiny, and the question I ask there is what were there reasons for preferring no plating? Also in non specialized connectors how do you clean off corrosion.
We will have more issues inside of our measurement equipment to compensate for the internal thermoelectric effects.

They were using heavy temperature equalizing blocks at every connection. They were not in an environment where green corrosion
happened, just brown copper oxide. They understood thermocouples. It can make a performance impact. 
What impact were they seeing?


For instance,
you could sell such a setup as a "thermocouple characterizing" test bench.

This would be useful, but irrelevant to the plated vs un-plated conversation.

This would require other things to design. outside of the scope of this conversation. I would be glad to discuss this, but this is also a solved problem, as I know of at least two commercial thermocouple calibrators on the market. The fluke 714 and Omega makes many many types.

There's another reason for no plating. What is that shiny plating on those commodity test leads? Hmmm....
Laws of intermediate metals don't apply to mystery metals, do they?

It applies to all metals, even alloys. It is all to do with the vacuum levels of the atoms and the alignment of the actual conduction bands. This also works with semiconductors, Thermoelectric coolers use P and N doped semiconductors to increase efficiency ( higher temperature per volt or amp )


Mainly though, no one is going to succeed with a kit product based on anything but high performance and quality. 

Agreed.

Competing on cost by having low quality won't work. 
No doubt.

I see this as one of the unsolved problems in the marketplace, 

I am not convinced yet...  Are you planning on making a nanovolt meter?

where ordinary Fluke meters are a "solved problem" that I and any of us niche market operators
should not attempt to touch. Or get burned. 
Agreed.

John Griessen


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