[volt-nuts] LTZ1000 project build

[Frank Stellmach]

This whole discussion does not really apply to the LTZ1000 circuit, that 
is the bare 7.15..V output, w/o step up amplifier, as all drift 
parameters were attenuated by orders of magnitude, depending on the 
resistors, R1-R5.


In the eevblog thread, several volt-nuts measured the real dependency, 
in contrast to the datsheet, which simply claims 1:100 attenuation for 
each of these resistors:



R1  R2  R3  R4  R5  author
120 7   7   12-15k  1k  
-1/770  -1/250  -1/1400 +1/100  
janaf
-1/600  -1/238  -1/1000 +1/87   
lars
-1/656  



TiN
1/714   1/250   1/  1/105   
bbs38hot
-1/670  -1/238  -1/1184 +1/74   -1/75   Andreas


Therefore, even humidity effects at most affect R4/R5, with 1/75 impact.

I also think, that it's possible for volt-nuts to measure such residual 
effects, by assembling several references, keeping the parameter of 
question (e.g. humidity or temperature) constant for the master 
reference, varying this paramater for a DUT, and evaluating the drift by 
monitoring the difference between the references.


Same goes for longterm drift, by using a group of many references (A man 
with one, two, three clocks..)


In the end, maintaining ultra precise references at first requires to 
care for controlled/constant ambient parameters, than to put too much 
effort to design references, which are immune to all possible drift factors.


Frank

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Re: [volt-nuts] LTZ1000 project build

[Dr. David Kirkby (Kirkby Microwave Ltd)]

On 4 Jun 2016 20:44, "Poul-Henning Kamp"  wrote:
>
> 
> In message <57527f8a.6070...@yandex.com>, Charles Steinmetz writes:
>
> >As I have mentioned before, for many years I have put precision circuits
> >that may be sensitive to humidity into gasketed metal boxes with fresh
> >silica gel packets.

> Only thing to remember is that it also reduces air circulation in the
> box and therefore increases thermal gradients.

I don't know how practical they are, but I have see humidity calibration
standards (e.g 50%). These  use a chemical reaction to keep a volume at a
constant humidity.  That might be a way of keeping the humidity constant,
without introducing increasing thermal gradients.

They might introduce a whole host of other problems,  so such a method
would need researching.

If a new PCB was designed,  it would be nice if there were pads to take the
expensive Vishay foil resistors,  in addition to a cheaper choice.

Dave
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Re: [volt-nuts] LTZ1000 project build

[Poul-Henning Kamp]

In message <57527f8a.6070...@yandex.com>, Charles Steinmetz writes:

>As I have mentioned before, for many years I have put precision circuits 
>that may be sensitive to humidity into gasketed metal boxes with fresh 
>silica gel packets.  I have opened some of these after 2 and 3 decades, 
>and even if there are some small leaks, or a vent hole to equalize 
>pressure, the silica gel has still been fully dry.

Only thing to remember is that it also reduces air circulation in the
box and therefore increases thermal gradients.


-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Re: [volt-nuts] LTZ1000 project build

[Charles Steinmetz]

Lars wrote:


if you have a completely sealed box with varying temperatures the
> relative humidity in the box changes if the humidity is not close to 
zero.


As I have mentioned before, for many years I have put precision circuits 
that may be sensitive to humidity into gasketed metal boxes with fresh 
silica gel packets.  I have opened some of these after 2 and 3 decades, 
and even if there are some small leaks, or a vent hole to equalize 
pressure, the silica gel has still been fully dry.


This is an easy solution, and works extremely well.

I second the suggestion that the main drift problem in a DIY voltage 
reference (apart from the reference itself) is the resistors that set 
the scaling amplifier gain (or the DAC or PWM drift, if you go that 
way).  If you can live without scaling, by all means do so.


Best regards,

Charles


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Re: [volt-nuts] LTZ1000 project build

[acbern]

the issue of resistor drifts is mainly related to the amplifier (7 to 10V) gain 
resistors, the other resistor drifts do have a very limited impact on the 
output (see data sheet).



> Gesendet: Freitag, 03. Juni 2016 um 23:47 Uhr
> Von: "Lars Walenius" <lars.walen...@hotmail.com>
> An: "volt-nuts@febo.com" <volt-nuts@febo.com>
> Betreff: Re: [volt-nuts] LTZ1000 project build
>
> 
> My experience is that boxes makes the time constants for humidity longer but 
> does not take it away. Heating in boxes takes the change due to humidity down 
> a little but it doesn´t go away. I have had boxes with LM399 and amps for 
> 7-10v with wirewounds for more than 20 years and they have definitely had 
> seasonal variations. Also if you have a completely sealed box with varying 
> temperatures the relative humidity in the box changes if the humidity is not 
> close to zero.
> 
> A 10V 2ppm ref on Ebay was said to have no humidity effect but my unit 
> definitely varied about 20ppm due to humidity during a long humidity test. 
> One guess I have is that some units have much longer time constants due to 
> better sealing but I am quite sure it doesn´t go away complete. Another 
> problem with humidity I have seen is that you may be cheated by humidity 
> changing over the season and cancelling the aging. This happened during my 
> first tests of AD587KRZ many years ago. During the first four months two 
> samples both had less than 2ppm drift and the humidity in the room changed 
> from 45 to 25%RH so they looked very promising. But during the next four 
> months when the humidity went up they drifted 15ppm.
> 
> Probably the 5 and 2ppm/C versions is manufactured in the same way. The 
> humidity graph under severe humidity and temperature testing shows a 500pm 
> difference for your chosen resistors. So doesn´t say so much. Hopefully they 
> are below 1ppm/%RH with low loads.
> 
> Lars
> 
> Från: Ian Johnston<mailto:i...@ianjohnston.com>
> Skickat: den 3 juni 2016 20:42
> Till: volt-nuts@febo.com<mailto:volt-nuts@febo.com>
> Ämne: Re: [volt-nuts] LTZ1000 project build
> 
> Hi,
> 
> The product I designed to use the 2ppm/degC resistors is sealed in an
> enclosure where the LM399AH etc live, so I don't expect much problem
> with humidity.
> 
> I use 2K2, 3.3K, 10K & 22K.
> 
> It's the RG2012L series from Susumu:-
> 
> http://datasheet.octopart.com/RG2012L-103-L-T05-Susumu-datasheet-13139546.pdf
> http://www.susumu.co.jp/common/pdf/n_catalog_partition01_en.pdf
> 
> The 2nd PDF above is mainly for the 5ppm versions but does contains
> various graphs including humidity.
> 
> Ian.
> 
> 
> 
> On 03/06/2016 17:01, Lars Walenius wrote:
> > Hi,
> >
> > Do you have any idea of the aging and humidity sensitivity of these 2ppm/C 
> > resistors?
> >
> > I have tested many resistors during the years and my opinion is that tempco 
> > is not the biggest problem for normal nuts use but of course may be if you 
> > sell a product. For a nut it is quite easy to check the tempco but not 
> > aging and humidity sensitivity.
> >
> > Of the resistors I have tested it is only hermetical sealed resistors that 
> > I don´t see a humidity sensitivity on. Even if they are bulk metal foil, 
> > wire wounds or metal films with low tempco´s they seem to have very varying 
> > humidity sensitivity if not sealed. Lower values of resistance (100-1k) 
> > normally seems to be better than 10-100kohm values that in all families may 
> > have up to 1-2ppm/%RH.
> > Last year I bought wire wounds, to be used in a LTZ1000 based design, that 
> > were supposed to be insensitive to humidity but they were not. They were 
> > even worse than other brands of WW and had several months of time constant. 
> > After a while the manufacturer admitted that it was a problem in the 
> > manufacturing and they were humidity sensitive. So far I haven´t received a 
> > replacement.
> >
> > Of course if you have a resistor with 2ppm/%RH and a seasonal variation of 
> > 50%RH it is only maximum 1ppm seasonal variation on the output on the LTZ. 
> > That is not easy to measure for most of us nuts.
> >
> > Lars
> >
> > Från: i...@ianjohnston.com<mailto:i...@ianjohnston.com>
> > Skickat: den 26 maj 2016 13:35
> > Till: il...@xdevs.com<mailto:il...@xdevs.com>; 
> > volt-nuts@febo.com<mailto:volt-nuts@febo.com>
> > Ämne: Re: [volt-nuts] LTZ1000 project build
> >
> > Hi all,
> >
> > TiN, out of interest I spent ages fishing for low ppm/degC resistors for my 
> > own reference..ended up with 2ppm units from 

Re: [volt-nuts] LTZ1000 project build

[David]

Could this be caused by ionic contamination of the printed circuit
board?  The quick test I have used for this is to blow on the board
with a straw.

In extreme cases solving it usually involved dropping the board into
an ultrasonic cleaner with water and a bit of dish soap or TSP, then a
rinse in pure (deionized, reverse osmosis, distilled, whatever) water,
and then another cycle in the ultrasonic cleaner with pure water.  Dry
with an air compressor and then bake out in an oven.

In production, we had to run boards through a dishwasher using
detergent and pure water before loading them with parts.

On Fri, 3 Jun 2016 23:47:05 +0200, you wrote:

>
>My experience is that boxes makes the time constants for humidity longer but 
>does not take it away. Heating in boxes takes the change due to humidity down 
>a little but it doesn´t go away. I have had boxes with LM399 and amps for 
>7-10v with wirewounds for more than 20 years and they have definitely had 
>seasonal variations. Also if you have a completely sealed box with varying 
>temperatures the relative humidity in the box changes if the humidity is not 
>close to zero.
>
>A 10V 2ppm ref on Ebay was said to have no humidity effect but my unit 
>definitely varied about 20ppm due to humidity during a long humidity test. One 
>guess I have is that some units have much longer time constants due to better 
>sealing but I am quite sure it doesn´t go away complete. Another problem with 
>humidity I have seen is that you may be cheated by humidity changing over the 
>season and cancelling the aging. This happened during my first tests of 
>AD587KRZ many years ago. During the first four months two samples both had 
>less than 2ppm drift and the humidity in the room changed from 45 to 25%RH so 
>they looked very promising. But during the next four months when the humidity 
>went up they drifted 15ppm.
>
>Probably the 5 and 2ppm/C versions is manufactured in the same way. The 
>humidity graph under severe humidity and temperature testing shows a 500pm 
>difference for your chosen resistors. So doesn´t say so much. Hopefully they 
>are below 1ppm/%RH with low loads.
>
>Lars
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Re: [volt-nuts] LTZ1000 project build

[Lars Walenius]

My experience is that boxes makes the time constants for humidity longer but 
does not take it away. Heating in boxes takes the change due to humidity down a 
little but it doesn´t go away. I have had boxes with LM399 and amps for 7-10v 
with wirewounds for more than 20 years and they have definitely had seasonal 
variations. Also if you have a completely sealed box with varying temperatures 
the relative humidity in the box changes if the humidity is not close to zero.

A 10V 2ppm ref on Ebay was said to have no humidity effect but my unit 
definitely varied about 20ppm due to humidity during a long humidity test. One 
guess I have is that some units have much longer time constants due to better 
sealing but I am quite sure it doesn´t go away complete. Another problem with 
humidity I have seen is that you may be cheated by humidity changing over the 
season and cancelling the aging. This happened during my first tests of 
AD587KRZ many years ago. During the first four months two samples both had less 
than 2ppm drift and the humidity in the room changed from 45 to 25%RH so they 
looked very promising. But during the next four months when the humidity went 
up they drifted 15ppm.

Probably the 5 and 2ppm/C versions is manufactured in the same way. The 
humidity graph under severe humidity and temperature testing shows a 500pm 
difference for your chosen resistors. So doesn´t say so much. Hopefully they 
are below 1ppm/%RH with low loads.

Lars

Från: Ian Johnston<mailto:i...@ianjohnston.com>
Skickat: den 3 juni 2016 20:42
Till: volt-nuts@febo.com<mailto:volt-nuts@febo.com>
Ämne: Re: [volt-nuts] LTZ1000 project build

Hi,

The product I designed to use the 2ppm/degC resistors is sealed in an
enclosure where the LM399AH etc live, so I don't expect much problem
with humidity.

I use 2K2, 3.3K, 10K & 22K.

It's the RG2012L series from Susumu:-

http://datasheet.octopart.com/RG2012L-103-L-T05-Susumu-datasheet-13139546.pdf
http://www.susumu.co.jp/common/pdf/n_catalog_partition01_en.pdf

The 2nd PDF above is mainly for the 5ppm versions but does contains
various graphs including humidity.

Ian.



On 03/06/2016 17:01, Lars Walenius wrote:
> Hi,
>
> Do you have any idea of the aging and humidity sensitivity of these 2ppm/C 
> resistors?
>
> I have tested many resistors during the years and my opinion is that tempco 
> is not the biggest problem for normal nuts use but of course may be if you 
> sell a product. For a nut it is quite easy to check the tempco but not aging 
> and humidity sensitivity.
>
> Of the resistors I have tested it is only hermetical sealed resistors that I 
> don´t see a humidity sensitivity on. Even if they are bulk metal foil, wire 
> wounds or metal films with low tempco´s they seem to have very varying 
> humidity sensitivity if not sealed. Lower values of resistance (100-1k) 
> normally seems to be better than 10-100kohm values that in all families may 
> have up to 1-2ppm/%RH.
> Last year I bought wire wounds, to be used in a LTZ1000 based design, that 
> were supposed to be insensitive to humidity but they were not. They were even 
> worse than other brands of WW and had several months of time constant. After 
> a while the manufacturer admitted that it was a problem in the manufacturing 
> and they were humidity sensitive. So far I haven´t received a replacement.
>
> Of course if you have a resistor with 2ppm/%RH and a seasonal variation of 
> 50%RH it is only maximum 1ppm seasonal variation on the output on the LTZ. 
> That is not easy to measure for most of us nuts.
>
> Lars
>
> Från: i...@ianjohnston.com<mailto:i...@ianjohnston.com>
> Skickat: den 26 maj 2016 13:35
> Till: il...@xdevs.com<mailto:il...@xdevs.com>; 
> volt-nuts@febo.com<mailto:volt-nuts@febo.com>
> Ämne: Re: [volt-nuts] LTZ1000 project build
>
> Hi all,
>
> TiN, out of interest I spent ages fishing for low ppm/degC resistors for my 
> own reference..ended up with 2ppm units from DigiKey. Yes, they are 
> expensive and send the BOM into the clouds!..so I know how you 
> feel!
>
> Ian.
>
>
> ----- Original Message -----
>   From: Illya Tsemenko [mailto:il...@xdevs.com]
>   To: volt-nuts@febo.com
>   Sent: Thu, 26 May 2016 18:42:54 +0800
>   Subject: [volt-nuts] LTZ1000 project build
>
>   I'm glad my little project got so much attention. Worth to mention few
> points regarding my (or any other LTZ1000) unit:
>
> A. One should consider cost of whole BOM, not only LTZ chip. In my case
> resistors from VPG exceed cost of LTZ1000 by far.
> B. PCB I designed was targeted best to my own application need, where
> compact size and direct output (whatever is coming out of LTZ) were key
> importance. Since modules are part of bigger system with DAC synth,
> specific value, like 7.150 was not im

Re: [volt-nuts] LTZ1000 project build

[Ian Johnston]

Hi,

The product I designed to use the 2ppm/degC resistors is sealed in an 
enclosure where the LM399AH etc live, so I don't expect much problem 
with humidity.


I use 2K2, 3.3K, 10K & 22K.

It's the RG2012L series from Susumu:-

http://datasheet.octopart.com/RG2012L-103-L-T05-Susumu-datasheet-13139546.pdf
http://www.susumu.co.jp/common/pdf/n_catalog_partition01_en.pdf

The 2nd PDF above is mainly for the 5ppm versions but does contains 
various graphs including humidity.


Ian.



On 03/06/2016 17:01, Lars Walenius wrote:

Hi,

Do you have any idea of the aging and humidity sensitivity of these 2ppm/C 
resistors?

I have tested many resistors during the years and my opinion is that tempco is 
not the biggest problem for normal nuts use but of course may be if you sell a 
product. For a nut it is quite easy to check the tempco but not aging and 
humidity sensitivity.

Of the resistors I have tested it is only hermetical sealed resistors that I 
don´t see a humidity sensitivity on. Even if they are bulk metal foil, wire 
wounds or metal films with low tempco´s they seem to have very varying humidity 
sensitivity if not sealed. Lower values of resistance (100-1k) normally seems 
to be better than 10-100kohm values that in all families may have up to 
1-2ppm/%RH.
Last year I bought wire wounds, to be used in a LTZ1000 based design, that were 
supposed to be insensitive to humidity but they were not. They were even worse 
than other brands of WW and had several months of time constant. After a while 
the manufacturer admitted that it was a problem in the manufacturing and they 
were humidity sensitive. So far I haven´t received a replacement.

Of course if you have a resistor with 2ppm/%RH and a seasonal variation of 
50%RH it is only maximum 1ppm seasonal variation on the output on the LTZ. That 
is not easy to measure for most of us nuts.

Lars

Från: i...@ianjohnston.com<mailto:i...@ianjohnston.com>
Skickat: den 26 maj 2016 13:35
Till: il...@xdevs.com<mailto:il...@xdevs.com>; 
volt-nuts@febo.com<mailto:volt-nuts@febo.com>
Ämne: Re: [volt-nuts] LTZ1000 project build

Hi all,

TiN, out of interest I spent ages fishing for low ppm/degC resistors for my own 
reference..ended up with 2ppm units from DigiKey. Yes, they are expensive 
and send the BOM into the clouds!..so I know how you feel!

Ian.


- Original Message -
  From: Illya Tsemenko [mailto:il...@xdevs.com]
  To: volt-nuts@febo.com
  Sent: Thu, 26 May 2016 18:42:54 +0800
  Subject: [volt-nuts] LTZ1000 project build

  I'm glad my little project got so much attention. Worth to mention few
points regarding my (or any other LTZ1000) unit:

A. One should consider cost of whole BOM, not only LTZ chip. In my case
resistors from VPG exceed cost of LTZ1000 by far.
B. PCB I designed was targeted best to my own application need, where
compact size and direct output (whatever is coming out of LTZ) were key
importance. Since modules are part of bigger system with DAC synth,
specific value, like 7.150 was not important for me.
C. If there is large enough group to have this project going, I can
actually modify original design (e.g. for easier hand soldering, or
added buffer or ratio circuits, onboard LDO, you name it) and get PCBs
made for interested nuts, at small cost.

You can also find lot of temco/stability data with
temperature/environment logs with mentioned LTZ modules on my site here:
https://xdevs.com/services/ in LTZ1000 voltage reference tests section.
RAW DSV data are available. I still have 3 modules at hand for any
testing/checks (one was sold while ago, one was installed in HP 3245A
source to replace LM399).

Illya "TiN" Tsemenko

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--

Ian Johnston
www.ianjohnston.com
https://www.youtube.com/user/IanScottJohnston
/"Because it feels good to make stuff!"/

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Re: [volt-nuts] LTZ1000 project build

[Lars Walenius]

Hi,

Do you have any idea of the aging and humidity sensitivity of these 2ppm/C 
resistors?

I have tested many resistors during the years and my opinion is that tempco is 
not the biggest problem for normal nuts use but of course may be if you sell a 
product. For a nut it is quite easy to check the tempco but not aging and 
humidity sensitivity.

Of the resistors I have tested it is only hermetical sealed resistors that I 
don´t see a humidity sensitivity on. Even if they are bulk metal foil, wire 
wounds or metal films with low tempco´s they seem to have very varying humidity 
sensitivity if not sealed. Lower values of resistance (100-1k) normally seems 
to be better than 10-100kohm values that in all families may have up to 
1-2ppm/%RH.
Last year I bought wire wounds, to be used in a LTZ1000 based design, that were 
supposed to be insensitive to humidity but they were not. They were even worse 
than other brands of WW and had several months of time constant. After a while 
the manufacturer admitted that it was a problem in the manufacturing and they 
were humidity sensitive. So far I haven´t received a replacement.

Of course if you have a resistor with 2ppm/%RH and a seasonal variation of 
50%RH it is only maximum 1ppm seasonal variation on the output on the LTZ. That 
is not easy to measure for most of us nuts.

Lars

Från: i...@ianjohnston.com<mailto:i...@ianjohnston.com>
Skickat: den 26 maj 2016 13:35
Till: il...@xdevs.com<mailto:il...@xdevs.com>; 
volt-nuts@febo.com<mailto:volt-nuts@febo.com>
Ämne: Re: [volt-nuts] LTZ1000 project build

Hi all,

TiN, out of interest I spent ages fishing for low ppm/degC resistors for my own 
reference..ended up with 2ppm units from DigiKey. Yes, they are expensive 
and send the BOM into the clouds!..so I know how you feel!

Ian.


- Original Message -
 From: Illya Tsemenko [mailto:il...@xdevs.com]
 To: volt-nuts@febo.com
 Sent: Thu, 26 May 2016 18:42:54 +0800
 Subject: [volt-nuts] LTZ1000 project build

 I'm glad my little project got so much attention. Worth to mention few
points regarding my (or any other LTZ1000) unit:

A. One should consider cost of whole BOM, not only LTZ chip. In my case
resistors from VPG exceed cost of LTZ1000 by far.
B. PCB I designed was targeted best to my own application need, where
compact size and direct output (whatever is coming out of LTZ) were key
importance. Since modules are part of bigger system with DAC synth,
specific value, like 7.150 was not important for me.
C. If there is large enough group to have this project going, I can
actually modify original design (e.g. for easier hand soldering, or
added buffer or ratio circuits, onboard LDO, you name it) and get PCBs
made for interested nuts, at small cost.

You can also find lot of temco/stability data with
temperature/environment logs with mentioned LTZ modules on my site here:
https://xdevs.com/services/ in LTZ1000 voltage reference tests section.
RAW DSV data are available. I still have 3 modules at hand for any
testing/checks (one was sold while ago, one was installed in HP 3245A
source to replace LM399).

Illya "TiN" Tsemenko

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[volt-nuts] LTZ1000 project build

[Frank Stellmach]

Hello,

I monitor two DIY LTZ1000 references, standard circuit from LT 
datasheet, since about 7 years.


These are running on 45°C, and are using 5 precision wirewound resistors 
(PWW), T.C. ~0.2 .. 4ppm/K.
BOM cost are currently 42.85$ for the LTZ1000 (non A!!) directly from LT 
(recommended, beware of chinese fakes), and about 7-10$ for each resistor.

So each reference may be built for about 100$ in total.

By avoiding some pitfalls, like excessive heating, causing hysteresis 
effects, these reference will have an annual stability of typ. 
-0.8ppm/year, without any special treatment, like "ageing", slots in the 
PCB, or usage of extremely sophisticated and expensive metal foil resistors.
One only has to monitor the drift of each reference if it's having this 
typical drift rate, or not.


Andreas Jahn currently makes a great job in investigating on the overall 
T.C. performance of his LTZ references, in terms of selecting these PWW 
resistors, trimming by 400k resistor, and LTZ lead length.


I'm doing that drift monitoring by comparison of a total of 4 
references, that's an additional LTZ1000A in a 3458A, pimped to 65°C, 
and not running continuously (practically no drift), and two stacked 
SZA263 in a Fluke 5442A, which have typ. +1ppm/yr, but this instrument 
also is not powered continuously.


The differences within this group are still within +1/-2ppm after 7 years.

The absolute uncertainty (w/o traceability) is estimated to 1ppm, as 
given by the initial calibration of the 5442A in 2009, one check vs. a 
freshly calibrated 8508A from another volt-nut in 2013 (+0.5ppm 
difference), and vs. two new 34465A last year (<0.5 ppm difference on 
10V range).


So it's really less complicated and less expensive than expected, to 
build and qualify LTZ references.


"Dr. Frank"
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Re: [volt-nuts] LTZ1000 project build

[Randy Evans]

Illya,

Very interesting.  The temco/stability data  does not plot but the X-Y
format seems to be OK.  Is it supposed to plot or do I have to plot it
myself with the csv data?

Thanks,

Randy Evans

On Thu, May 26, 2016 at 3:42 AM, Illya Tsemenko  wrote:

> I'm glad my little project got so much attention. Worth to mention few
> points regarding my (or any other LTZ1000) unit:
>
> A. One should consider cost of whole BOM, not only LTZ chip. In my case
> resistors from VPG exceed cost of LTZ1000 by far.
> B. PCB I designed was targeted best to my own application need, where
> compact size and direct output (whatever is coming out of LTZ) were key
> importance. Since modules are part of bigger system with DAC synth,
> specific value, like 7.150 was not important for me.
> C. If there is large enough group to have this project going, I can
> actually modify original design (e.g. for easier hand soldering, or added
> buffer or ratio circuits, onboard LDO, you name it) and get PCBs made for
> interested nuts, at small cost.
>
> You can also find lot of temco/stability data with temperature/environment
> logs with mentioned LTZ modules on my site here:
> https://xdevs.com/services/ in LTZ1000 voltage reference tests section.
> RAW DSV data are available. I still have 3 modules at hand for any
> testing/checks (one was sold while ago, one was installed in HP 3245A
> source to replace LM399).
>
> Illya "TiN" Tsemenko
>
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Re: [volt-nuts] LTZ1000 project build

[ian]

Hi all,

TiN, out of interest I spent ages fishing for low ppm/degC resistors for my own 
reference..ended up with 2ppm units from DigiKey. Yes, they are expensive 
and send the BOM into the clouds!..so I know how you feel!

Ian.


- Original Message -
 From: Illya Tsemenko [mailto:il...@xdevs.com]
 To: volt-nuts@febo.com
 Sent: Thu, 26 May 2016 18:42:54 +0800
 Subject: [volt-nuts] LTZ1000 project build

 I'm glad my little project got so much attention. Worth to mention few 
points regarding my (or any other LTZ1000) unit:

A. One should consider cost of whole BOM, not only LTZ chip. In my case 
resistors from VPG exceed cost of LTZ1000 by far.
B. PCB I designed was targeted best to my own application need, where 
compact size and direct output (whatever is coming out of LTZ) were key 
importance. Since modules are part of bigger system with DAC synth, 
specific value, like 7.150 was not important for me.
C. If there is large enough group to have this project going, I can 
actually modify original design (e.g. for easier hand soldering, or 
added buffer or ratio circuits, onboard LDO, you name it) and get PCBs 
made for interested nuts, at small cost.

You can also find lot of temco/stability data with 
temperature/environment logs with mentioned LTZ modules on my site here: 
https://xdevs.com/services/ in LTZ1000 voltage reference tests section. 
RAW DSV data are available. I still have 3 modules at hand for any 
testing/checks (one was sold while ago, one was installed in HP 3245A 
source to replace LM399).

Illya "TiN" Tsemenko

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[volt-nuts] LTZ1000 project build

[Illya Tsemenko]

I'm glad my little project got so much attention. Worth to mention few 
points regarding my (or any other LTZ1000) unit:


A. One should consider cost of whole BOM, not only LTZ chip. In my case 
resistors from VPG exceed cost of LTZ1000 by far.
B. PCB I designed was targeted best to my own application need, where 
compact size and direct output (whatever is coming out of LTZ) were key 
importance. Since modules are part of bigger system with DAC synth, 
specific value, like 7.150 was not important for me.
C. If there is large enough group to have this project going, I can 
actually modify original design (e.g. for easier hand soldering, or 
added buffer or ratio circuits, onboard LDO, you name it) and get PCBs 
made for interested nuts, at small cost.


You can also find lot of temco/stability data with 
temperature/environment logs with mentioned LTZ modules on my site here: 
https://xdevs.com/services/ in LTZ1000 voltage reference tests section. 
RAW DSV data are available. I still have 3 modules at hand for any 
testing/checks (one was sold while ago, one was installed in HP 3245A 
source to replace LM399).


Illya "TiN" Tsemenko

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Re: [volt-nuts] LTZ1000 project build

[John Phillips]

What prices are you seeing for 100 LTZ1000s?
The main thing is they need to be cooked in then sorted for stability.
A good data acquisition system used to do stats on all the units would
really help.

On Wed, May 25, 2016 at 10:17 PM, Andreas Jahn 
wrote:

> Hello,
>
> there are further projects (including measurement results of Illya = TiN)
>
> in this thread:
>
> http://www.eevblog.com/forum/metrology/ultra-precision-reference-ltz1000/
>
> and others in the metrology/projects section of eevblog
>
>
> http://www.eevblog.com/forum/projects/project-kx-diy-calibrator-reference-sourcemeter/
>
> With best regards
>
> Andreas
>
>
> Am 25.05.2016 um 17:27 schrieb Eric Garner:
>
>> I ran across this:
>> https://xdevs.com/article/kx-ref/
>>
>> this morning and thought I'd share.
>>
>>
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>



-- 

*John Phillips*
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Re: [volt-nuts] LTZ1000 project build

[Andreas Jahn]

Hello,

there are further projects (including measurement results of Illya = TiN)

in this thread:

http://www.eevblog.com/forum/metrology/ultra-precision-reference-ltz1000/

and others in the metrology/projects section of eevblog

http://www.eevblog.com/forum/projects/project-kx-diy-calibrator-reference-sourcemeter/

With best regards

Andreas


Am 25.05.2016 um 17:27 schrieb Eric Garner:

I ran across this:
https://xdevs.com/article/kx-ref/

this morning and thought I'd share.



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Re: [volt-nuts] LTZ1000 project build

[David Garrido]

Heck, if you’re going to make one, you might as well make one GREAT.

I would be interested in doing a 4910 version, so to speak.  Four in one 
thermal box and the ability to use them independently or summed and averaged.  
Similar to the Fluke 730a, I think?  Oh, and one of them must be removable for 
transportation.  :  )

Of course, if properly designed one could build any number of them into 
whatever box they can podge together and use the boards as they please.  I’m 
in!!  I would find it difficult to believe we could not find 100 individuals 
that would buy at least one.  The challenge is buying the LTZ’s in enough QTY 
to grade them like Solartron did in the 7071 and 81’s.

David


> On May 25, 2016, at 9:42 PM, bownes  wrote:
> 
> 
> As Dr K said, traceable and usefully calibrated are not necessarily 
> connected. 

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Re: [volt-nuts] LTZ1000 project build

[bownes]

As Dr K said, traceable and usefully calibrated are not necessarily connected. 

I can calibrate to any arbitrary standard I like.  That standard need not be 
traceable if all that is important to me is consistency across all the 
instruments in my lab. 

If I, on the other hand, want to be consistent with someone else's lab, then we 
need to be traceable to a common source. Thus NIST. I presume most countries 
have a NIST like organization. How often to they cross check each other?

Accreditation, on the other hand can be, as the good Dr. points out, pretty 
useless unless the accreditation body is, itself, held to some (professional) 
standard. 

And I'd also love to build one of these if there is enough interest. While I'm 
sure we can't get enough orders to get the 100pcs discount on the LTZ1000, it 
would be a great group project and I'd be willing to participate in bringing it 
to fruition. I'm also sure I can find a calibrated, traceable, reliable 3458 in 
the area code. 

The irony  is that while I'm less than 15Km from the New York State Bureau of 
Weights & Measures Metrology group, which has all the traceable standards for 
the state, they cannot do high accuracy for time or voltage. My personal house 
standards are better than theirs for those two. By a lot. Adding one of these 
would add a few more orders of magnitude...:)


> On May 25, 2016, at 17:06, Dr. David Kirkby (Kirkby Microwave Ltd) 
>  wrote:
> 
>> On 25 May 2016 at 19:24, Russ Ramirez  wrote:
>> 
>> A lot of great information Eric, thanks for sharing the link.
>> 
>> Due to my ignorance in general on the subject of Metrology, I have the
>> following question for the list.
>> 
>> If one built a project with the LTZ1000, like the one described on xDevs
>> and could set it to a value of 7.1500v at the NIST lab, and observed
>> stability to 7 1/2 digits, would using that device to calibrate your own 7
>> 1/2 digit DMM be considered NIST traceable? Let's say your device is well
>> insulated and battery powered, and your calibration was done at the same
>> altitude and room temperature as at NIST, plus anything I left out that
>> would make the conditions ideal.
>> 
>> The above was not meant to be a trick question, and I may have asked it
>> incorrectly, but I view the answers as instructive - or I hope they are.
>> 
>> Russ
> 
> As far as I can determine, as long as you can work out the uncertainties,
> no matter how large they might b,  the measurement is traceable. If you use
> a 3.5 digit multimeter that is NIST traceable to calibrate a 7.5 digit
> multimeter, the calibration is still NIST traceable. The calibration will
> be pretty useless, and you may not be accredited, but it is still NIST
> traceable.
> 
> Or if you want to be accredited, get your mate down the local pub (bar) to
> accredit you!
> 
> On a more serious note, if people felt that design was good, and wanted to
> produce the PCBs. and/or make parts available, I'd be interested. I only
> have a 6.5 digit meter, but feel sure I could find someone with a 3458A in
> the UK who could measure the voltage for me.
> 
> Dave 
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Re: [volt-nuts] LTZ1000 project build

[Russ Ramirez]

A lot of great information Eric, thanks for sharing the link.

Due to my ignorance in general on the subject of Metrology, I have the
following question for the list.

If one built a project with the LTZ1000, like the one described on xDevs
and could set it to a value of 7.1500v at the NIST lab, and observed
stability to 7 1/2 digits, would using that device to calibrate your own 7
1/2 digit DMM be considered NIST traceable? Let's say your device is well
insulated and battery powered, and your calibration was done at the same
altitude and room temperature as at NIST, plus anything I left out that
would make the conditions ideal.

The above was not meant to be a trick question, and I may have asked it
incorrectly, but I view the answers as instructive - or I hope they are.

Russ

On Wed, May 25, 2016 at 10:27 AM, Eric Garner  wrote:

> I ran across this:
> https://xdevs.com/article/kx-ref/
>
> this morning and thought I'd share.
>
> --
> --Eric
> _
> Eric Garner
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[volt-nuts] LTZ1000 project build

[Eric Garner]

I ran across this:
https://xdevs.com/article/kx-ref/

this morning and thought I'd share.

-- 
--Eric
_
Eric Garner
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