Author Topic: Ultra Precision Reference LTZ1000  (Read 958931 times)

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Offline notfaded1

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Re: Ultra Precision Reference LTZ1000
« Reply #2900 on: February 23, 2020, 07:07:04 am »
It just wouldn't be fun not build some of my own... I am interested in converting this into a non-LTZ reference though.  That's why I asked about best way to safely cut PCB's... IDK about tin snips but I know it's been done.  It's in a working 8842A now.  Somehow the reference might be more fun than the old MM to me I think.

Bill
Didn't you build an enclosed 10V reference with this method @Micke?
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Offline Micke

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Re: Ultra Precision Reference LTZ1000
« Reply #2901 on: February 23, 2020, 09:30:11 am »
Yepp, I had a 8842A DMM beyond rescue...
I just used a hacksaw to cut out RefAmp, thought of using Dremel as well, but thought that hacksaw would generate less vibrations, and easier make a straight cut.
Could have made RefAmp board even smaller, but wanted to be on the safe side, and to have somewhere to put mounting screws...
I soldered power +/- 15V directly on Op-amp pins U702 on the secondary side. For Ground, I used the via holes just under the text "C103" (think shield was soldered in these holes originally)
I am not very impressed by the stability though, typical run with FLUKE 8846A below (PLC100), SZA263 in metal box with lid on, powered 24/7 for weeks:
* Min  10.00005V
* Max 10.00010V
* Avg 10.00007V
* SD 7,6µV
* 40000 # samples
So a span of 5ppm between Max and Min, did expect better actually!
 
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Offline imo

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Re: Ultra Precision Reference LTZ1000
« Reply #2902 on: February 23, 2020, 12:02:00 pm »
Quote
So a span of 5ppm between Max and Min, did expect better actually!
SZA263 is a zener with a transistor on the chip. You cannot expect "LTZ1000 stability" unless the module is ovenised, imho.
 

Offline SilverSolder

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Re: Ultra Precision Reference LTZ1000
« Reply #2903 on: February 23, 2020, 01:19:48 pm »
[...]
* Min  10.00005V
* Max 10.00010V
* Avg 10.00007V
* SD 7,6µV
* 40000 # samples
So a span of 5ppm between Max and Min, did expect better actually!

5ppm over several weeks is not too shabby?  Is the area temperature controlled?
 

Offline Micke

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Re: Ultra Precision Reference LTZ1000
« Reply #2904 on: February 23, 2020, 07:04:09 pm »
[...]
* Min  10.00005V
* Max 10.00010V
* Avg 10.00007V
* SD 7,6µV
* 40000 # samples
So a span of 5ppm between Max and Min, did expect better actually!

5ppm over several weeks is not too shabby?  Is the area temperature controlled?

Did not record start/stop time, but 40000 samples at PLC100 is unfortunately only like 22h
Yeah, did not expect LTZ1000 performance, but I am pretty sure the SZA263 drift more than my AD581LH (need to find the notes from the measurenents... ;) )
 

Offline maginnovision

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Re: Ultra Precision Reference LTZ1000
« Reply #2905 on: February 24, 2020, 04:26:39 am »
I've finally started logging voltage and temp together. I'm using 1 array of 10 DS18B20's to measure ambient, 1 array of 5 for each of 2 meters. The placement for the arrays for the meters is essentially placed between the ADC and the reference. Is that the best place to measure the internal temp, or should it be more central to the analog board?
 

Offline branadic

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Re: Ultra Precision Reference LTZ1000
« Reply #2906 on: February 28, 2020, 06:18:59 pm »
Hi,

I tested Analog Discovery 2 spectrum analyzer function together with pipelies LNA (0.1 ... 10Hz) and found that this is a decent setup, without the need of a boat anchor on the desk. Thought that could be of interest for you guys. As an example I measured LNA with shorted input, a 9V battery and one of my LTZ references.

-branadic-
Metrology Meeting 2020 is canceled. Looking forward for MM2021
 
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Offline SilverSolder

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Re: Ultra Precision Reference LTZ1000
« Reply #2907 on: February 28, 2020, 07:06:41 pm »

[...]  together with pipelies LNA (0.1 ... 10Hz)  [...]


What is the "pipelies LNA" ?
 

Offline branadic

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Metrology Meeting 2020 is canceled. Looking forward for MM2021
 
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Offline branadic

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Re: Ultra Precision Reference LTZ1000
« Reply #2909 on: April 04, 2020, 12:15:56 pm »
I always wondered how the noise spectrum of my LTZ references would look like. Sure we can use DMM readings to get a raw idea, but even the 1/f region is always hard to get. Now that I have one of those nice Digital Spectrum Analyzers (Advantest R9211) or as they are also called Dynamic Signal Analyzers or FFT Analyzers, I was acutally able to create such a nice noise plot today.

-branadic-
Metrology Meeting 2020 is canceled. Looking forward for MM2021
 
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Offline SilverSolder

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Re: Ultra Precision Reference LTZ1000
« Reply #2910 on: April 04, 2020, 12:26:39 pm »
I always wondered how the noise spectrum of my LTZ references would look like. Sure we can use DMM readings to get a raw idea, but even the 1/f region is always hard to get. Now that I have one of those nice Digital Spectrum Analyzers (Advantest R9211) or as they are also called Dynamic Signal Analyzers or FFT Analyzers, I was acutally able to create such a nice noise plot today.

-branadic-

That is very cool!  -  what is the noise floor of an instrument like that?

 

Offline splin

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Re: Ultra Precision Reference LTZ1000
« Reply #2911 on: April 04, 2020, 01:34:56 pm »
Hi,

I tested Analog Discovery 2 spectrum analyzer function together with pipelies LNA (0.1 ... 10Hz) and found that this is a decent setup, without the need of a boat anchor on the desk. Thought that could be of interest for you guys. As an example I measured LNA with shorted input, a 9V battery and one of my LTZ references.

-branadic-

An LTZ1000 with no flicker noise?   :-//
 

Offline Andreas

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Re: Ultra Precision Reference LTZ1000
« Reply #2912 on: April 04, 2020, 01:36:20 pm »
Mhm,

I can explain the 50 Hz peak in the spectrum: your cookies box isnt tight enough.
But where do the 60 Hz come from? (Screen frequency of the instrument?)

with best regards

Andreas
 

Offline Castorp

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Re: Ultra Precision Reference LTZ1000
« Reply #2913 on: April 04, 2020, 04:26:53 pm »
Looks just like the LTZ1000 spectra I've measured many times in different ways.  :-+

My 89441A does produce 60 Hz internally, and sometimes it does show in the measurements.

 

Offline notfaded1

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Re: Ultra Precision Reference LTZ1000
« Reply #2914 on: April 16, 2020, 10:25:41 pm »
My precision resistors are coming pretty soon I found out today!  I just got these for the binding posts on my references.  I'm hoping these will help some.
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Offline maginnovision

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Re: Ultra Precision Reference LTZ1000
« Reply #2915 on: April 18, 2020, 09:59:39 pm »
Has anybody used Grafana to visualize data while logging? I'm doing this but I'm currently using a single right hand y axis for temps but the Internal temps are pretty far from Ambient. Does anybody know how to add a second Y axis? You can see the issue I have and maybe you can understand why I'd like dual scales to get more detail even if it may not be all that necessary. If you have any tips please share!

EDIT: http://172.119.228.219:3000/dashboard/snapshot/F3ptvJ1tIbHtU7X4roRV3Qlm0h5WboFv?orgId=1 Here is a link to a snapshot, since not everyone is using a 4k monitor.
« Last Edit: April 19, 2020, 04:21:21 am by maginnovision »
 

Offline e61_phil

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Re: Ultra Precision Reference LTZ1000
« Reply #2916 on: April 19, 2020, 07:00:26 am »
I used relative ppm instead of volt for the Y scaling in Grafana. Two Y Axis will have different scalings and the reference voltages are hard to compare.
 
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Offline maginnovision

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Re: Ultra Precision Reference LTZ1000
« Reply #2917 on: April 19, 2020, 07:06:06 am »
I used relative ppm instead of volt for the Y scaling in Grafana. Two Y Axis will have different scalings and the reference voltages are hard to compare.

That's on my list. I had some trouble getting the C++ interface for influxdb working right and since it's running I'm just going to let it go and get back to it after the ~7 days it logs(it logs to a CSV file, and a more verbose log as well as influx). Did you do that through math IN grafana or by passing the ppm data?
« Last Edit: April 19, 2020, 07:07:46 am by maginnovision »
 

Offline e61_phil

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Re: Ultra Precision Reference LTZ1000
« Reply #2918 on: April 19, 2020, 07:14:53 am »
I stored raw data in influxdb (using Python) and calculated everything in Grafana, but one have to be careful with the queries on big sets of data. I killed my server several times (I have several million entries in influxdb)
 

Offline maginnovision

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Re: Ultra Precision Reference LTZ1000
« Reply #2919 on: April 19, 2020, 09:19:07 am »
I stored raw data in influxdb (using Python) and calculated everything in Grafana, but one have to be careful with the queries on big sets of data. I killed my server several times (I have several million entries in influxdb)

Would you be able to share how you do that? I'm having trouble calculating the mean and then using that to convert to PPM. The results always end up returning null.
 

Offline e61_phil

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Re: Ultra Precision Reference LTZ1000
« Reply #2920 on: April 19, 2020, 11:25:02 am »
Imho you can’t mix aggregate and non-aggregate data in a query. Therefore, I used a constant in the query. I know it is very ugly, sorry. If you find a good solution to calculate each point together with the mean of all points it would be very nice to know.
 
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Offline SilverSolder

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Re: Ultra Precision Reference LTZ1000
« Reply #2921 on: April 19, 2020, 11:31:01 am »
Imho you can’t mix aggregate and non-aggregate data in a query. Therefore, I used a constant in the query. I know it is very ugly, sorry. If you find a good solution to calculate each point together with the mean of all points it would be very nice to know.

You can, in Oracle at least  (Oracle Analytics).   Other databases probably have something similar.  Look for the OVER clause.
 

Offline e61_phil

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Re: Ultra Precision Reference LTZ1000
« Reply #2922 on: April 19, 2020, 11:36:23 am »
I was taking about influxdb
 

Offline SilverSolder

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Re: Ultra Precision Reference LTZ1000
« Reply #2923 on: April 19, 2020, 01:24:18 pm »
I was taking about influxdb

Is it possible to export the data and process it further in a different DB, where you don't need the high flow performance?
 

Offline maginnovision

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Re: Ultra Precision Reference LTZ1000
« Reply #2924 on: April 19, 2020, 03:11:20 pm »
Well I attempted both select mean("reading") as "mean"... And it worked but all nulls. I also tried select mean("reading') into "autogen"."mean"... Both cases they create "mean" and it's correctly populated but when using it in math like I said it just returns null for every data point. Maybe I'll try tracking the mean in my program and continuously updating it and then attempting to use the most recent one for the math. In my program I also have it perform 43 readings to stabilize(using a scanner) before logging so perhaps that's another place to get my mean value from, then I'll be able to have 1 constant mean value for every reading point. I'll try some things in a few days when it's finished. If nothing else a hard constant isn't that bad.
 


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