One of the things we got hit up for on our last A2LA audit was record keeping, or more specifically tracking of our lab's primary voltage standard. It is a Zener reference standard with outputs at 10, 1, 1.018 volts and separate 10 volt outputs for 4 individual standard zener reference cells. We have a scanner which automatically switches between the readings of the outputs using a good bench multimeter, a HP3458A, then we print out a hard copy of all the readings, the averages, standard deviation, etc.

Now where our problem lies is the software that controls the scanner is very old, running in DOS, and through the years, through successive reorganizations and computer crashes all the data that the software has saved has been lost, leaving us with nothing to work with but stacks of printouts. The data from the printouts is now being entered onto an excel spreadsheet where the voltage outputs, std. deviation, etc. could be plotted, but in my opinion our simple excel spreadsheet is inadequate.

So what I'm looking for is a program, database or spreadsheet, of minimal cost (open source if possible), that I can enter in all the old data (and new too) that is easy to use understand both for me (and auditors). Anybody else out there who has to keep up with laboratory voltage standards have any ideas? :confused:

As I don't have that requirement, I haven't had to deal with it (although for practical purposes I need to spend some time on this in the near future).

However, on the webpage where I read your posting, I saw to the right an ad toolbar listing a number of SPC tools. My experience tells me that you need to look at the bottom line of what you want to really know about your DC references. And that is (oversimplified) an understanding of short and long term drift, bias/error (distance from nominal), an understanding of where the measurands are relative to each other. And from this, your predicted DC values and uncertainties (again, vastly oversimplified).

If it were me, I would be analytically walking through what it is I need to maximize accuracy of my DC measurements. I have always been a little of a rebel in that I never try to satisfy auditors any more than is necessary in the regard that my first responsibility is to make my customers measurements the best they can be. This is something I would be deliberate about, to assure I was not just correcting an audit deficiency (although that is needed), but providing what my customers need.

If the DC voltage and associated uncertainties assure a safety related module in an airplane, an automobile, or perhaps an instrument used in a hospital to monitor cardiac parameters, then my responsibility is to the people who use that product. I add this side note as background thoughts about what software you may purchase or develop.

I know Excel can produce some pretty powerful statistical results. However, if the amount of time spent in gathering and processing the data is prohibitive, could be custom software is needed.

Sorry for the rambling. I am more of a philosopher than an engineer sometimes. But hopefully the above inputs will be of some value.

Perhaps a good solution is to put it into an Access database. Access can easily export toExcel so the results are easy to view, and Access is much more powerful.

Hershal

Fluke has got an excellent paper about this. I believe the title is " Maintaining Zener Voltage standards to 0.3 ppm" or something like that on their website.
I found this paper excellent and wrote a excel spreadsheet mimicking this process.