[volt-nuts] Batch of old reference zeners

[Andreas Jahn]

Hello Bob,

the instrument will be your least worries.
with 20-80ppm/K you will need a very well stabilized (<0.1K) temperature 
environment for the references.
Otherwise you will not detect ageing but the temperature of your 
environment.

A volt nut would only use the LM329 from the list (buried zener).
The others are bandgap references with much larger ageing drift.
But to detect ageing after some 100 hrs you will need a well stabilized 
current source (< 0.1% drift during setup)
or a even better voltage source (<0.05% over temperature and ageing) and 
a rather stable resistor for each reference in the setup.

If you use sockets for the references their drift will outperform the 
reference drift if the board is handled (e.g. for measuring)
so you will need to have a (relay-) multiplexer for your instrument.
If you solder the references to a board you will create stress to the 
device and this will give a large initial drift after soldering.

with best regards

Andreas


Am 10.03.2014 01:35, schrieb Bob Albert:
> I have a 3456A.  Is that good enough?
>
>
> Bob
>
>
>
>
> On Sunday, March 9, 2014 4:41 PM, Jan Fredriksson <jan at 41hz.com> wrote:
>   
> I have a batch of voltage references ICs on the shelf, several thousand of
> each type. They all have date codes of around 1983, ie 30 years old. It
> would be great to have some drift data on them.
>
> The ones listed below are the best of the bunch.
>
> - AS431, TO-92 and SOIC-8, 20ppm/C 120nV/sqrtHz (0.5% or 0.1%?)
>
> - LM385Z, TO-92, 80ppm/C, 600nV/SqrtHz, 60uV, 20ppm/SqrtKhr
>
> - LM329CZ, TO-92, 75nV/sqrtHz, 30ppm/C 7uV noise 20ppm (8ppm?) /SqrtKhr.
> - AS2951/2954, SOIC-8, 20ppm/C
>
> I am willing to send a handful (like at least 50 pcs) to anyone who can set
> up and monitor the drift of them for a few months and send me some data.
>
> Any takers?
>
> I will do similar monitoring myself, but would appreciate data from others,
> that's why I am doing this.
>
> I am also building some other references to compare with, based on LTZ1000
> and other zeners.
>
> I am not asking anything in return, except that you return drift data,
> measured with some decent method, ie single digit ppm stability.
> If you happen to have some resistors rated like 10ppm/C or lower, surface
> or hole mount, I'd appreciate some of those in return, in values 1K-10K,
> but that is not a requirement.
>
> Jan
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