[volt-nuts] Experiment: tilting LTZ reference

Andreas Jahn Andreas_-_Jahn at t-online.de
Sat Sep 18 07:05:19 UTC 2010

>  For Andreas - never did such a crazy experiment before.
Thanks for doing the experiment.

For me its just a missing spec in the datasheet which
seems to be important for heated references.

Others could be the relative humidity for plastic cases
or power-on hysteresis on low power devices.

I found this effect by accident when I missed 30uV
between calibration location and home between the
two LM399 references. Unfortunately I had not
payed attention to the orientation of the devices
at the calibration.

The most weird thing I observed is the fact
that the two Keithleys show exact the same
reading of my 7V references when the one
instrument is orientated in 0 degrees and the
other in 90 degrees. So I am wondering what
the guys at the calibration lab are doing when
they have not much space on the table or 
if this result is by luck.

When I have built my reference and pre-aged
I will compare your LTZ1000 with 12K/1K
setpoint to my LTZ1000A which will have
12K5/1K (UPW50) setpoint. If the effect
depends on the difference between environment
and setpoint temperature I should be worse.
If it depends on heater power I could have
had luck.

By the way: can you estimate the room temperature 
which was during the experiment?

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