[volt-nuts] Traveling Standards - Measuring Protocol

[John Devereux]

Hi Warren,

Do you have a feel for how these golden 1N825 tend to be distributed?
For example. are ~10% of them ~10 times better than the rest in terms of
stability? More like 1%?

And, what is the stability of an unselected part?

Thanks,

John


"WarrenS" <warrensjmail-one at yahoo.com> writes:

> A good thing to include in the "Measuring Protocol"
> The type of filtering used  and a 24 hr plot would be a great thing to show.
>
> In the LM399 data reported below, Its noise starts at 10-30 uv PP  (3 PPM)
> Once per minute averaged readings gave 2 uv PP (0.3 PPM)
> 21 min moving average data is below 0.5 uv PP  (under 0.1 PP)
> The PP variation over a couple hours time where the temperature is not
> changing is about 0.5 PPM
>
> What I've seen is that the LM399 has good TC over a wide temperature
> but they
> can be pretty noisy PP short and medium term when measured at the sub
> PPM level.
>
> The total PP noise on the plot I posted of the selected 1N825#2,
> running at its 'Zero-TC' current
> shows about 0.1 PPM variation over the couple hours where the
> temperature is not changing.
> The plot is once per second samples taken from with a 15 sec analog RC
> filter time constant.
> http://www.febo.com/pipermail/volt-nuts/attachments/20110904/15d2a3ab/attachment-0001.jpg
>
> All 1N825 are not the same. Starting with a selected low noise one,
> it must then be aged and run in at 50 ma for a long time before it is
> fully stabilize.
>
> ws
>
> ***********************
>> From: "Andreas Jahn" <Andreas_-_Jahn at t-online.de>
>> To: "Discussion of precise voltage measurement" <volt-nuts at febo.com>
>>
>>Hello,
>>
>>the red curve is one measurement with an integration time of 1 minute.
>>(about 350 measurement values of LTC2400 ADC with 10-30uVpp
>>noise averaged giving around 2 uVpp for 1 minute integration time).
>>
>>the light blue trace is the sliding average over 21 minutes of
>>the red curve.10 minutes before, current minute and 10 minutes after.
>>(so noise is reduced down to below 0.5uVpp).
>>
>>Total measuremen time (x-Axis) is around 940 minutes.
>>
>>with best regards
>> Andreas 
>
>
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-- 

John Devereux