gEDA-user: Design Lab Equipment

[Steven Michalske]

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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