Andreas_-_Jahn at t-online.de
Thu Sep 16 21:47:39 UTC 2010
thanks for your tips and especially the link to rhopoint.
>remember, that the LTZ circuitry attenuates all drifts of the 5 crucial
>resistors by 1/100 (120, 1k, 13k) and by 1/300 (70k).
>So the Z201 resistors are a little bit overkill, 1-3 ppm/K for lower grade
>metal foil or wirewound ones are sufficient for a low T.C. of the completed
You are right.
on the other side my "lab" is not a thermally controlled room.
I have 18 degrees in winter and up to 33 degrees this summer.
Perhaps I will use two 25K of Z201 and the 70K of rhopoint.
>So, for the LTZ1000A you should set the temperature to 55°C at least, what
>you obviously intended to do.
Ok thanks for reviewing my design.
>Two 25k in parallel over the 1k will do the job, don't they?
Yes. but one single resistor would cost less space
which makes it easier for mechanical/thermal decoupling of
>I will test the stability under rotation for my LTZ box this weekend,
thats more than I could expect. Thanks in advance.
> but the HP3458A stays where it is, sorry ;-)
I can understand this. And I swear that on the two Keithleys,
where I had access to, the effect was reversible with orientation.
At least for the resolution of 10uV in the 10V-Range.
Only the owner looked a little strange when I showed him
the accuracy of his instruments.
>Where did you get the Z201 from, did you order custom specific values, or
They are catalog types from RS.
>What about the price and delivery time?
see link: (delivery from store)
digikey also has some single values:
They have also the UPW50-types which I use for my first build with 3 ppm
(pre-aged with rated load for 2000 hours 1,5 hours on and 0,5 hours off at
They look much like the Rhopoint Economistors.
>I'm looking for the hermetically encapsulated/oil filled types as a
I have heard that ECOMAL is a big Vishay distributor. (search for VHP)
>And did you order the LTZs at Linear in USA directly, or via distributor?
I ordered them by the "Bauteilbeschaffungsservice" of Conrad.
The Package is labeled by LTC with Distributor "Setron" as receiver.
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