Personal lab cal chain

[zhtoor]

I have a Weston cell, it is more than 30 years old and still deliver the same voltage 

i have 6 of them - manufactured in february 2004
(will build an oven for them when i get around it - courtesy of @blackdog / Bram - an excellent teacher of ovens.)

https://www.eevblog.com/forum/metrology/poor-man-gets-his-candies-(6x-weston-cells)/msg1333980/#msg1333980

best regards.

-zia

[quarks]

as mentioned before, if you are a hobbiest like me, who is hunting for as good as possible accuracy and not making money with it, you most likely decide to own your own calibration gear instead of spending money for traceability. Also I by now spend a lot more money than I ever would have thought, when I started,  for me it was the right way to go.

[kj7e]

I'm stuck asking the same question, do I want all my gear to be as close to NIST as possible or just to all agree with each other knowing they are still close to NIST.  Ill still send my newer instruments in for factory cal, but it bugs me how they never seem to quite agree down to the LSD.

This drive my OCD off the charts;


I just picked up my latest bit of metrology gear, a nice Simpson 260-8, I'm just going to use it as my new standard so everything else will now match 

In all seriousness, I forked over some real cash for a meter, many times better than I will ever really need (DMM7510).  This is my house reference standard that I fall back on.  I know its not perfect or have absolute accuracy to NIST, its even possible my 34465A my even be closer, but I have no way to know for certain, so I have to trust my best meter as my house standard.

[PA4TIM]

Always forget the last digit.

A Simpson 260 as golden reference is the way to go, here I calibrate one of my ESI-1010 resistors with my 260. And as you can see, the 1010 is spoton

[precaud]

The fact is, in 40 years of working for electronics firms, even making very precise scientific instruments, absolute calibration to better than about 3.5 digits hasn't been necessary. Relative measurements to a dozen ppm have sometimes been necessary, but you don't need NIST for ratios.

Yes, in my case I've been working in the electronics industry since the mid/late 1980s and I've rubbed shoulders with many hundreds of talented engineers from the world of RF/SW/HW/DSP and in all that time I have never seen any of them get remotely interested in any >=5.5 digit DMM each time one of these meters came back from NAMAS/UKAS calibration. So it isn't just me (or you).

Tone it down.... you guys are being far too realistic   

[Conrad Hoffman]

No fear, not needing it at work has driven me to ever lower ppm numbers "needed" at home. 

[GEOelectronics]

"Ha, making fixtures and tools to make more tools is my life."

Ditto here.


George Dowell

[FriedLogic]

I'm stuck asking the same question, do I want all my gear to be as close to NIST as possible or just to all agree with each other knowing they are still close to NIST.  Ill still send my newer instruments in for factory cal, but it bugs me how they never seem to quite agree down to the LSD.

Hi,

This might be where the Calibration Club / Travelling Standard approach could be useful. A reference made specifically to travel well, and which is regularly checked against stable references, could be a very accurate way to check calibration.... assuming that anything can be made to travel unknown paths well!
I would have thought that it could be made to travel better than a multimeter anyway.

[acts238willy]

I see precious metal (copper-plated) in the background...
WillyB

[kj7e]

That's to intimidate my projects, they will work right or else...

[nanofrog]

That's to intimidate my projects, they will work right or else...

I guess the rest of us are still cavemen by comparison, relying on big freaking hammers. 

[Conrad Hoffman]

I use walls of test equipment to intimidate the circuits. Not that I ever use 1/100 of it, but the weight of it alone would squash any pcb like a bug.

[zhtoor]

I use walls of test equipment to intimidate the circuits. Not that I ever use 1/100 of it, but the weight of it alone would squash any pcb like a bug.

we have these here in pakistan for circuit-intimidation (thats me BOOTSTRAPPING the cow )

best regards.

-zia

[nanofrog]

Good aim ^.

[eurofox]

I use walls of test equipment to intimidate the circuits. Not that I ever use 1/100 of it, but the weight of it alone would squash any pcb like a bug.

we have these here in pakistan for circuit-intimidation (thats me BOOTSTRAPPING the cow )

best regards.

-zia

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