[time-nuts] OT: Basics of voltage calibration?
Dr. Frank Stellmach
drfrank.stellmach at freenet.de
Sun Mar 22 11:01:53 EDT 2009
To John Ackermann!
My recommendation for documents about DC-voltage-standards are the Fluke
Go to service/manuals, e.g.:
They still produce the best and most accurate DC calibrators and
standards, and to my biggest pleasure, they recently scanned all manuals
of actual and outdated devices.
The manuals contain schematics, setup of complete reference system, and
best read 'principle of operation'.
For a complete system, you need the following devices / instruction
manuals, just search for the product names and download:
1. Zener based Voltage References: 731A, 732A, 732B, 7000 (LTZ based,
For the actual 7000 system, also search for the underlying UK patent GB
2 258 356 A, from John Robert Pickering (1993).
The temperature hysteresis of the LTZ1000 zener reference is mitigated
by a temperature cycling process.
2. Calibrators: 332A, 332D, 335D, (old devices, but very instructive for
complete system); 5700A, 5720A
3. Kelvin Varley Divider: 720A (7 digits, 0.1ppm linearity)
4. Reference Divider: 752A (provides highly accurate transfers of 1:100,
1:10, 1:1, 10:1, 100:1 for the 5 cardinal DC points)
5. Null detector: 845A (see also schematics of 335D)
To learn about precision resistors, goto vishay site, ultra high
precision resistors, technical and application notes, datasheet:
Also: "Zero TC Foil Resistor, Ten Fold Improvement in Tempertaure
Coefficient", Reuven Goldstein et.al.
Brian Kirby already summed up the other most important sources.
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