[volt-nuts] Batch of old reference zeners

M K m1k3k1 at hotmail.com
Mon Mar 10 04:00:12 EDT 2014


Hi,

I have an 8.5 digit wavetek, and a bunch of Solartron and wavetek 7.5 
digit meters, but it seems to me that doing justice to the 329 
references is going to need stable wirewound or foil resistors, and a 
few months will be only just long enough.

MK

On 10/03/2014 07:12, Andreas Jahn wrote:
> 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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