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Re: gEDA-user: Design Lab Equipment


On Mar 31, 2007, at 12:16 PM, John Griessen wrote:

al davis wrote:

How about lab test equipment. There is a real need for simple stuff that is too simple to market at the high prices the big instrument companies need to charge. The kind of equipment you need in a home lab. Like Heathkit used to make.
In kit form? I know an Austin EE bought the music synthesizer kit business PAIA
and that has a life of its own for many decades...

There does seem to be a lack of inexpensive metrology and yet it often needs fancy coax
and such that's hard to get low low cost...

One thing that would be good is pure copper terminals for connecting up test leads with
no accidental thermocouple effects, and supply it as a kit with compatible pure coper terminals
meters and the meter would sell too, wouldn't it?

All the inexpensive meters, Fluke included, have undesirable plating on the terminals....

Would you please elaborate on the undesired effect.

Here is y counter for having the plating.

I would like to point you towards the law of intermediate metals. It states that if you take a third metal and place it in between the original two metals, in an isothermal environment. The connection then behaves as only the two outer metals. This means that the thermoelectric effect has to have a thermal gradient across the connector, to make any appreciable effect. I doubt that out meters would notice less than 40uV of thermal electric effect
When you put a plating on the connection it protects the copper from corroding, a much larger problem. The oxides cause a resistance to build up on the contacts. This will cause more problems than the plating.

The expensive equipment had gold plating on its contacts.

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.

temperature probes and
volt probes too... but hard to imagine cottage manufacturing of them...

Another real need is for the hardware side of computer instrumentation. Something like the commercial product "Labview". We have most of the software. We are lacking the hardware.

Are you thinking ethernet? What's your fave software for emulating Labview functions?

John Griessen




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