EEVblog Electronics Community Forum
Electronics => Metrology => Topic started by: lowimpedance on May 29, 2018, 06:24:00 am
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Came back to my office to find a couple of old LT component boxes on the desk, left by a fellow recycler who knew I collected "this stuff" and couldn't throw it away :phew:.
So the contents were a small quantity of rather elderly LTZ's of varying ages of 1986, 87 and 88 that have never been used :-+.
See pictures below. Interesting that some have gold plated legs and others do not, (as with the 90 vintage I already have which are not gold plated either)
For a bit of fun I plugged one of the 86 vintage refs into an old burn in board I had lying around and out popped 7.13V after 32 years sitting around :D.
Apparently each of these units cost $78 way back then according to the writing on the box. I wonder how many LTZ's of this age that have never been used are still in existence ?.
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Nice score!
Maybe you will get lucky and two of them will be exactly 100mV apart, giving you a dual LTZ ref with a bonus 100mV ref.
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No one throws such a treasure on MY desk ... :-//
^-^
:-+
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Do you want to sell something from it?
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That's some EE porn! :D
Apparently each of these units cost $78 way back
About ~$150 in 2018 $, taking into account the inflation. They were pretty expensive back then!
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lowimpedance always find a way to reach out volt-nut vibes.
I bet should be some hundreds of these chips somewhere :).
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Just curious, has anyone ever made any correlation to a particular vintage being more stable than others? Would NOS be desired for any reason over the newer parts? Does aging only occur when the part is in an active circuit or does some ageing occur over time even in storage?
My intuition leans toward, newer parts may be preferred due to newer, modern manufacturing techniques and possibly higher purity silicon. Any aging in storage is virtually insignificant. However, is it possible the early chips where more carefully made, maybe before any manufacturing cost optimizations. Maybe someone would have some insight.
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That is very nice to find on your desk!
I wish that happened to me...
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Just curious, has anyone ever made any correlation to a particular vintage being more stable than others? Would NOS be desired for any reason over the newer parts? Does aging only occur when the part is in an active circuit or does some ageing occur over time even in storage?
A single data-point: The lowest noise part I measured also happened to be a used part, from 1998. https://github.com/cellularmitosis/logs/blob/master/20180324-ltz1000-1f-noise/README.md However, one data-point isn't sufficient -- I think the more likely cause is either luck, or a manufacturer selecting low-noise parts in 1998.
My intuition leans toward, newer parts may be preferred due to newer, modern manufacturing techniques and possibly higher purity silicon. Any aging in storage is virtually insignificant. However, is it possible the early chips where more carefully made, maybe before any manufacturing cost optimizations. Maybe someone would have some insight.
I think Andreas is curious if since Fukishima, silicon die purities are not as high as they used to be, and 1/f noise and popcorn noise are more prevalent since then. I don't think we have enough data-points to say yet though.
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Just curious, has anyone ever made any correlation to a particular vintage being more stable than others? Would NOS be desired for any reason over the newer parts? Does aging only occur when the part is in an active circuit or does some ageing occur over time even in storage?
My intuition leans toward, newer parts may be preferred due to newer, modern manufacturing techniques and possibly higher purity silicon. Any aging in storage is virtually insignificant. However, is it possible the early chips where more carefully made, maybe before any manufacturing cost optimizations. Maybe someone would have some insight.
French people use to say "c'est dans les vieux pots qu'on fait la meilleure soupe"
It is in the old casseroles that you make the best soup
Sometimes they mean about food but women as well: :-DD
Mmm but I don't think you can use this for voltage reference components :palm:
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Calm down, there is an answer. And that is: YES!
The only question is, belongs to which question... ;D
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An interesting experiment would be to put them 6 in a burn in board with 3 running continuously and 3 only powered intermittently and compare the drift over 3 months running the intermittent set once a week for a few hours.
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As they're never used but only mummified for decades NIB, whats the "technical" advantage of this old references say compared to newly manufactured ?
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They need to make a new series of voltage reference. This thing is ancient now. 30 years. We need 9.5 digits.
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It's a question of demand. I don't know of any actual applications requiring 6.5 digit absolute accuracy, much less anything better. The LTZ1000 seems to be viewed as "the best" here, but looking at all the shenanigans needed to extract maximum performance from it, who could put a better chip to use and what would you compare it to? There's been no shortage of new references with targeted applications from a number of vendors. Money and orders talk, the rest walk.
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They need to make a new series of voltage reference. This thing is ancient now. 30 years. We need 9.5 digits.
That's it, why i post such a statement:
https://www.eevblog.com/forum/metrology/vintage-ltz1000-from-1986-nib-!/msg1574092/#msg1574092 (https://www.eevblog.com/forum/metrology/vintage-ltz1000-from-1986-nib-!/msg1574092/#msg1574092)
:clap: :popcorn:
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Cellurarmitosis “Maybe you will get lucky and two of them will be exactly 100mV apart, giving you a dual LTZ ref with a bonus 100mV ref.”
You might not need two LTZ1000A references exactly 100mV apart because you can change the ref voltage somewhat by selecting the values of R2 and R3 (the two 70K resistors). While I was waiting for two 75K precision resistors to be delivered for one of my references, I temporarily put two 68K 1% resistors in place to see that everything was working. With two 68K resistors I got 7.08355 volt and with the two 75K I got 7.08005 volt or about .0035 volt difference. With two references you could conceivably set one high and one low and change the difference by up to .007 volt. You’d still need two references fairly close but that would be easier to find than two exactly on. Just a thought.
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Hello,
Larger adjustments can be done with the temperature setpoint resistors.
with best regards
Andreas
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As they're never used but only mummified for decades NIB, whats the "technical" advantage of this old references say compared to newly manufactured ?
Well certainly these old timers would need to be put through the same testing as a freshly made one to see any differences, how ever the sample shown has powered up perfectly fine after three decades, and there is also sample units of the 90's date code running happily with another 'volt nut' here who has collected quite a bit of data history on it ;). So I would anticipate these REF's to be still good even after their "mummification"... umm long rest.
I could donate a few samples for further experimentation to those that have the time and resources to add more data points for comparison.
Plenty of old LTZ's but short on time and other 'bits' !.
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If any of these old LTZ1000CH references are going to be compared against modern parts should the new references also be non "A" versions as well because of the difference in recommended heater temperature?
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To be a fair comparison that should be the case. Still it would be interesting to see long term drift measurements with one of these oldies.
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To be a fair comparison that should be the case. Still it would be interesting to see long term drift measurements with one of these oldies.
I have one of CH'es dated 2016, and about 20 of ACH's from 175x week to compare with, if you want me to compare one of these oldies.
All these are still waiting for voodoo resistors.
One of your "newer" 90's datecode CH is running in my 3458A since February 2016, as I replaced jumpy ebay-speziol ACH with it, on HP A9 board. I'll get Wavetek 7000 after calibration next month, so it will be turn of this 3458A to be recalibrated, and then I can get additional drift point since. So far, based on test in October 2017, DCV annual drift is -1.89ppm (CAL? 2,1 data). As additional note - both my 3458A's are running 24/7/365 at reduced oven temperature (100K over native 15K setting resistor).
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Hi,
if you want I can test some LTZ1000 for you. I have three LTZ1000CH based on the circuit from Andreas and my LTZ1000 with a board that is shown in AN86. I have 4 resistor sets left, that I could use for a fair comparison. I'm located in Germany.
-branadic-
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Ohhh ho ho ho look what arrived in the mail today! :scared: 8) 8) 8)
I'll be testing these parts for 1/f noise, temperature set-point (find the R4/R5 ratio at which regulation drops out at room temperature), and if I have time, I'll see if I can compare their temperature coefficients.
lowimpedance has been very generous and has donated these parts "to the cause" :-+ I think its time we had a few more members on this forum with LTZ references! I'll add a bit to his generosity and throw in a circuit board with each.
As far as who to give them to... perhaps I should draw six random names from the list of members who are currently signed up for cal club round 2? And if one of them wishes to decline, I'll draw another name instead. If you have any ideas on this matter, feel free to share them!
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I see a ref01 , what are the other 2 cans.
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I see a ref01 , what are the other 2 cans.
Some sort of matched fets (marked K146), looks like two TO-92's with a little aluminum hat.
edit: looks like the K146 is a pair of 2SK146 https://www.semicon-data.com/transistor/tfet/k0/K146.html (https://www.semicon-data.com/transistor/tfet/k0/K146.html)
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cellularmitosis :-+
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Ok, here is an initial effort to find the R4/R5 temperature set-point "offset" of an LTZ1000 (non-A).
There are two ways to find this offset: either use a fixed R4/R5 and place the circuit into an oven, slowly ramping the temperature until the voltage falls out of regulation, or use a fixed temperature (ambient) and adjust the R4/R5 ratio until fall into and/or out of regulation. Here, I'm using the latter technique.
The setup: R4 of a px-ref board has been broken out to a decade box, so that I can manipulate the temperature set-point. The meter is a Keithley 2015 at "medium" speed with a 10-reading moving average filter.
I've spliced the footage from the three cameras together, but I haven't edited the result into smaller chunks, so I'll just list a timeline of here:
0:00 Camera sync-up.
0:30 Approaching the ambient set-point from below (100-ohm resolution). 10.4k to 10.5k to 10.6k create steps of about 29uV. We are not yet in thermal regulation.
1:00 The 10.6k to 10.7k step diverges from the 29uV behavior.
1:30 10.8 to 10.9 to 11.0 create steps of about 77uV. We are now in thermal regulation.
1:45 Decreasing the set-point while so close to the regulation limit results in very slow response.
2:10 Switching to 10-ohm resolution. When just under regulation, adjusting the resistance has no effect (10.85 through 10.89).
2:30 10-ohm steps create steps of about 8uV when in regulation (probably, the steps are actually 7.7uV).
3:07 Using a fan to create forced cooling, to approach the ambient set-point from above.
4:00 10.86k is in regulation.
4:15 10.85k is in regulation.
4:24 10.84k is in regulation.
4:35 10.83k is in regulation (using the fan).
4:45 10.82k is in regulation (using the fan).
4:57 10.81k is in regulation (using the fan), but self-heating due to zener-current slowly pushes it out of regulation.
5:22 Self-heating drift of 8uV up from the 10.81k set-point, which also means the 10.82k set-point isn't with regulation at equilibrium.
5:39 Drift reaches 16uV, so ambient regulation must be above the 10.83k set-point.
5:55 24uV drift; 10.84k is not within regulation at equilibrium.
6:12 31uV, so 10.85k isn't regulated.
6:45 39uV, so 10.86k isn't regulated.
7:15 7.7uV times 6 steps would be 46uV. The drift is really slowing down as we cross over 47uV, so 10.87k isn't in regulation, but we are very close now (at ~23.5C).
7:25 At 48uV of drift, we verify that 10.87k isn't in regulation, and we verify that 10.88k is in regulation. We then decrease back to 10.87k, and the drift starts falling again, indicating the chip is cooling off, which verifies that 10.88k is in regulation at 23.46C.
So, at 23.46C, we drop out of regulation somewhere between an R4 value of 10.88k and 10.87k.
https://youtu.be/mbSmjaNA8xc
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Having gone through this exercise and thought about this a bit more, I now understand why the LTZ1000A needs a higher thermal set-point than the non-A chip. If the thermal resistance to ambient is ~5x greater, then the same (~4mA * 7V) 28mW of zener power dissipation will result in more self-heating in an "A" chip than a non-A chip.
Thus, for a given ambient environment, you must operate the A chip at a higher thermal set-point to maintain regulation.
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Having gone through this exercise and thought about this a bit more, I now understand why the LTZ1000A needs a higher thermal set-point than the non-A chip. If the thermal resistance to ambient is ~5x greater, then the same (~4mA * 7V) 28mW of zener power dissipation will result in more self-heating in an "A" chip than a non-A chip.
Thus, for a given ambient environment, you must operate the A chip at a higher thermal set-point to maintain regulation.
Yep, per the data sheet ~ 10 deg C higher set point for the 'A' version is recommended.
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Completed the rest of the R4 / temperature "ambient offset" measurements, both for lowimpedance's LTZ1000's as well as some LTZ1000A chips (and an LTZ1000) which I have on hand. All measured in the same (socketed) board, using the same decade resistor setup shown in the above video.
I found, on average, that the A chip needs set-point which is 228 ohms higher than non-A chips. Assuming a slope of 20 Ohms / C near 23C, this means the A chip needs an set-point which is 11.4 degrees higher than the non-A chip. Pretty close to the datasheet values.
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Approaching this from another angle:
I measured the voltage across the 120R zener resistor at 0.541V, which makes the zener current 4.5mA. With Vref at 7.077V, that makes Vz 6.536V, which means zener self-heating is 29.5mW.
For a non-A chip with 80C/W thermal resistance, that's a 2.357C temperature rise.
For an A chip with 400C/W, that's a 11.787C temperature rise.
That's a difference of 9.429C -- pretty close to the 10C datasheet value. However, I'm not accounting for the heating due to current in the two transistors in the LTZ1000, which would push my figure a bit closer to 10C.
Taking my 228 Ohm average difference, that makes a slope of about 24 Ohms / C at ambient.
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However, using the formula (which I think Dr. Frank derived), the R4 operating point agrees pretty closely, but the slope near 23C is more like 40 Ohms / C.
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Ohhh ho ho ho look what arrived in the mail today! :scared: 8) 8) 8)
As far as who to give them to... perhaps I should draw six random names from the list of members who are currently signed up for cal club round 2? And if one of them wishes to decline, I'll draw another name instead. If you have any ideas on this matter, feel free to share them!
That would be amazing! :-+ :-+ :-+. I've been waiting to pull the trigger on building my own ltz ref. Now may be the time!
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lowimpedance has been very generous and has donated these parts "to the cause" :-+ I think its time we had a few more members on this forum with LTZ references! I'll add a bit to his generosity and throw in a circuit board with each.
As far as who to give them to... perhaps I should draw six random names from the list of members who are currently signed up for cal club round 2? And if one of them wishes to decline, I'll draw another name instead. If you have any ideas on this matter, feel free to share them!
Man, I cannot believe almost a month has already slipped by. Unfortunately hobby time has been very scarce lately.
I had hoped to have a working demo of my latest PX ref board ready by now, so that I could offer a board + the resistor chip along with the LTZ from lowimpedance, but I have held up this thread for 3 weeks already, and I don't want to stall any further.
So, here are 6 random names drawn from this go-round of the cal club:
- TWMIV
- Svgeesus
- orin
- GEOelectronics
- Vacuuminded
- bitseeker
Congrats to you guys! :-+
Along with the LTZ I will include a PX-ref board of your choice:
A v2.4.2 board, which is the same as 2.4.1 but with some slight tweaks to the thermal copper ring which surrounds the LTZ. This board fits inside of a TEKO 371.16 steel enclosure.
A v2.5 board, which is a longer version of 2.4.2, which is meant to mount the input and output filter ferrites directly onto the board (see photo). This fits in the slightly longer TEKO 372.16 steel case.
A v2.6 board, which uses an OHMTEK multi-resistor chip which I found on taoboa for divider and the two 70k resistors. A 120R resistor needs to be supplied separately, and the footprint for that will accommodate a metal foil or wire-wound resistor. Note however that I soldered up an example of this board and for some reason it rails the heater control fully on, so probably best not to choose this option until I get the issue figured out.
I'll message each of you to arrange shipping and such :-+
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Just curious, has anyone ever made any correlation to a particular vintage being more stable than others? Would NOS be desired for any reason over the newer parts? Does aging only occur when the part is in an active circuit or does some ageing occur over time even in storage?
To be a fair comparison that should be the case. Still it would be interesting to see long term drift measurements with one of these oldies.
Kind of sad that we now won't see a fair comparison between the vintage specimen as they will now be seperated, tested under different conditions on different board designs and with different instruments. Could have been an interesting investigation if there is any hint on a correlation :(
-branadic-
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Today I found some in dumpster too!
(https://xdevs.com/doc/xDevs.com/FX/candy_1.jpg) (https://xdevs.com/doc/xDevs.com/FX/candy.jpg)
Old days Linear was better than today, that's for sure. Nice package with ESD-safe sponge. Modern orders they just toss poor LTZ's into bag and ship it, flying and non-secured inside the bag.
(https://xdevs.com/doc/xDevs.com/FX/old_candy_1.jpg) (https://xdevs.com/doc/xDevs.com/FX/old_candy.jpg)
Some speciol chips here too.
(https://xdevs.com/doc/xDevs.com/FX/all_candies_1.jpg) (https://xdevs.com/doc/xDevs.com/FX/all_candies.jpg)
Added into my 1000A stash (new arrivals = row on top.)
LM394H and cute dual matched JFET (?) pairs (I'd assume that is from Keithley 146?) will be interesting feat too.
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Today I found some in dumpster too!
Can you please guide me to what kind of dumpster I have to look for such a find? :-DD
-branadic-
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Today I found some in dumpster too!
Can you please guide me to what kind of dumpster I have to look for such a find? :-DD
-branadic-
I sustain this, I want one as well, if not a full carton ;D
Cheers,
DC1MC
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Can you please guide me to what kind of dumpster I have to look for such a find? :-DD
Tin sold his soul to Satan a long time ago. Those parts came out the dumpster behind some low-rent brothel in hell. >:D
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Can you please guide me to what kind of dumpster I have to look for such a find? :-DD
Those parts came out the dumpster behind some low-rent brothel in hell. >:D
:-DD :-DD :-DD :-DD :-DD :-DD :-DD How did you know :D :D :D. Now that has made my day :-+
AND........
From now on y'all keep ya greasy mits outa my dumpster...... :)
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Today I had some Australian dumpster find, too. LTZ1000CH with date code 8628, 8716, 8830 as well as 9015. Seems like some worldwide reference infection is going around.
-branadic-
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Hello,
Suitable to the 1986 devices the data sheet from the LT 1986 databook (printed in 1985).
So the 86 datecode are very early (preliminiary?) devices.
with best regards
Andreas
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lowimpedance has been very generous and has donated these parts "to the cause" :-+ I think its time we had a few more members on this forum with LTZ references! I'll add a bit to his generosity and throw in a circuit board with each.
As far as who to give them to... perhaps I should draw six random names from the list of members who are currently signed up for cal club round 2? And if one of them wishes to decline, I'll draw another name instead. If you have any ideas on this matter, feel free to share them!
I had hoped to have a working demo of my latest PX ref board ready by now, so that I could offer a board + the resistor chip along with the LTZ from lowimpedance, but I have held up this thread for 3 weeks already, and I don't want to stall any further.
So, here are 6 random names drawn from this go-round of the cal club:
- TWMIV
- Svgeesus
- orin
- GEOelectronics
- Vacuuminded
- bitseeker
Congrats to you guys! :-+
Along with the LTZ I will include a PX-ref board of your choice:
A v2.4.2 board, which is the same as 2.4.1 but with some slight tweaks to the thermal copper ring which surrounds the LTZ. This board fits inside of a TEKO 371.16 steel enclosure.
A v2.5 board, which is a longer version of 2.4.2, which is meant to mount the input and output filter ferrites directly onto the board (see photo). This fits in the slightly longer TEKO 372.16 steel case.
A v2.6 board, which uses an OHMTEK multi-resistor chip which I found on taoboa for divider and the two 70k resistors. A 120R resistor needs to be supplied separately, and the footprint for that will accommodate a metal foil or wire-wound resistor. Note however that I soldered up an example of this board and for some reason it rails the heater control fully on, so probably best not to choose this option until I get the issue figured out.
I'll message each of you to arrange shipping and such :-+
Thank you, lowimpedance and cellularmitosis for the generous giveaway! And thanks to Andreas for the period-matching databook.
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Hello,
This has taken forever and a day but I have finally tested the 1/f noise of these LTZ's. I'll be shipping them out shortly! :-DMM
I've followed the same setup as I used last time: https://github.com/cellularmitosis/logs/blob/master/20180324-ltz1000-1f-noise/README.md
The probe multiplier has been set to 100x, and the 1/f noise amplifier has a gain of 10,000x, so just mentally drop down one SI unit class in your mind when looking at these scope shots (i.e., if it says mV, that's actually uV).
Here's the LTZ with date code 8628, on which I've placed one dot:
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Here's the chip with date code 8628, which I've marked with two dots:
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Here's the chip with date code 8830:
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Here is the chip with date code 9015, which I've marked with one dot.
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Here's the chip with date code 9015, which I've marked with three dots:
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And here's the chip with date code 9015 with four dots.
(the 6th chip, 9015 with three dots, was mailed out to Svgeesus before I had the chance to test the 1/f noise, sorry!)
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The probe multiplier has been set to 100x, and the 1/f noise amplifier has a gain of 10,000x, so just mentally drop down one SI unit class in your mind when looking at these scope shots (i.e., if it says mV, that's actually uV).
You must be wrong, 1/f noise in the order of a few hundred µVpp on a LTZ1000 is far to much. My references show 1/f noise <1.6ppm peak-peak for the 10V output.
(https://www.eevblog.com/forum/metrology/diy-low-frenquency-noise-meter/?action=dlattach;attach=568990;image)
-branadic-
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My mistake, that should have been two unit classes (i.e., if it shows mV, that's actually nV).
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I finished 9x LTZ1000 references (8628, 8716, 8830, 3x 9015, 3x 1811) with currently buffered zener output voltage only. Another one dated 1811 was finallized before and is with Greg since the beginning of the year.
https://www.eevblog.com/forum/metrology/ultra-precision-reference-ltz1000/msg2178047/#msg2178047 (https://www.eevblog.com/forum/metrology/ultra-precision-reference-ltz1000/msg2178047/#msg2178047)
I'm still not sure if NOMCA16032001 is the right way to go to boost output voltages to 10V. Need to perform some measurements as well as T.C. measurements and most likely T.C. optimization on the references themself. But they are all powered on since 24.02.2019, measurements have started and will be updated continuously.
What I can say for now, the 3 specimen manufactured in 9015 have a large difference in zener voltage, while all three specimen from 1811 are much closer to each other. Noise still looks a little high and I have to improve my power supply cabling to minimize noise pick up, I know that it's not perfect.
-branadic-
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Are the noise measurements 7V buffered or direct from zener output?
-> noise contribution from buffer (https://www.eevblog.com/forum/metrology/ultra-precision-reference-ltz1000/msg2208078/#msg2208078)
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It's the noise of the buffered output.
-branadic-
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I finished 9x LTZ1000 references ...
If at any time you should be willing to sell an assembled, tested and characterized 10v boxed reference, I would like to buy one. I am not overly concerned about a bit noise, TC and drift, so I will be happy with a medium performer.
I like this "low-voodoo" no-psychedelic-colors & no-whistles-and-bells design. Thanks.
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First 265h of data with the references continuously running with 9x LTZ1000CH in the design of the group buy, plus 3x LTZ1000CH based on the design of Andreas plus my 2DW233 reference in an oven. Shown is the difference from initial value in volts plus standard deviation plus temperature.
-branadic-
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Update: ~400h
-branadic-
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Update:
Results after 1000h, I changed from Prema 5017 SC to R6581D on 31.03.2019 which results in lower standard deviation of readings by meter, but also accelerated measurements as I get a reading within 4s instead of 10s. The values shown are the average of 10 readings per reference.
2DW233 reference is still drifting downwards, but shows quite large std, need to investigate on that.
So let's start the next 1000h and hopefully get higher resolution results with the "new" meter.
-branadic-
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Beside measurement for monitoring aging I today started measuring the different references for 1 hour to detect abnomal behavior and immediately found LTZ1000 #1 (date code 1986) to be a jumper (popcorn noise), while #2 to #9 are looking fine.
-branadic-
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Hi All,
Can someone measure the pin pitch on these old vintage parts.
I suspect the pitch for say pre 2000 is around 6.2mm rather than 5.08mm as stated in the current package.
This has been puzzling me for some time and I am sure this is the case.
Rob
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Can't confirm that. All the references (1986, 1987, 1988, 1992, 2018) fitted into the same footprint on the board without any issue. Maybe your specimen is a counterfeit part?
-branadic-
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Hi,
Can't confirm that. All the references (1986, 1987, 1988, 1992, 2018) fitted into the same footprint on the board without any issue. Maybe your specimen is a counterfeit part?
The 6.2mm pitch spacing refers to calculated spacing taken from photographs of the 03458-66509 reference board for the HP 3458 multimeter.
So I have thought of 3 possibilities:
- The legs were offset (bent) outwards to fit the holes - this seems to be the case as it is clear all the legs are bent outwards on the solder side.
- The holes in the pads were say 1mm diameter, allowing for the legs (0.45mm dia.) to fit on the inside edge of the holes.
- The photo is not linear and while the pitch of known parts in the centre of photo can be used to check spacing of close by parts, other parts near the edge of the board will appear to have greater spacing - after close inspection of the printed photo, it does appear to be very linear.
Only a side photo of a vintage 03458-66509 board would answer this puzzle.
Thanks
Rob
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Can't confirm that. All the references (1986, 1987, 1988, 1992, 2018) fitted into the same footprint on the board without any issue.
Same here, all LTZs I've seen/bought are same pin pitch.
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Vintage HP3458A LTZ1000
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Midi,
Now that it has been established the vintage parts have the same pitch, then it must be a slight angling of the legs.
You can see on the solder side the pads have centres which are greater than the span of 2 pins of 8 Pin op amp and 2 of the socket holes.
Could you take a side photo of the ref board to show the legs?
Hopefully we should see a slight angle and this might have been done to assist with manual soldering of the part into place.
Regards Rob
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Sorry, pictures were taken before I read this post.
It had a bend cap that was fixed and it is now back in my meter.
Not shure why this is so important, nobody has confirmed change in pitch...
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Hi Midi,
The layout is important to me as I am designing a replica copy of the original 03458-66509 board but without actually owning one, so it all has to be done from photos like yours.
From the tests carried out on the vintage LTZ1000 parts, is there a conclusion that the vintage parts produce more noise than the modern parts?
Also, could it be these vintage parts were part of a larger set that were all tested / sorted and these were the parts that were not as good.
I wonder if the heater power is linked to this low frequency noise, so the harder the heater is driven (for the higher die temperatures) the more the die temperature fluctuates and creates a greater swing in the noise level. If the radiated and conducted heat loss is kept low, then perhaps the noise swing will reduce.
I know that it has been said running the LTZ1000 at a reduce temperature will dramatically improve the long term stability.
Running at a higher temp. accelerates the aging process towards long term stability, but at the same time reduces its life span.
Rob
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Rob,
you can save your time and simply order the boards for it as another person already did that work for you.
https://oshpark.com/profiles/pepaslabs/page/4
-branadic-
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Rob,
you can save your time and simply order the boards for it as another person already did that work for you.
https://oshpark.com/profiles/pepaslabs/page/4 (https://oshpark.com/profiles/pepaslabs/page/4)
-branadic-
let him build his own, building things is fun :)
I shared some mechanical data here https://www.eevblog.com/forum/metrology/3458a-a9-voltage-reference-pcb-mechanical-data-(03458-66509) (https://www.eevblog.com/forum/metrology/3458a-a9-voltage-reference-pcb-mechanical-data-(03458-66509))
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Some update... I changend from Prema 5017 to R6581D in march 2019 which got calibrated in june 2019 at Metrology Meeting 2019, thus the big jump in the data. I moved 3458A from work to my home in august 2019, to get additional datapoints, that are not shown here, but used LTZ-1000-1, -2 and -3 to verify that this succeeded without additional changes/jumps. So experiement is still running and I take measurements monthly.
-branadic-
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Sorry that I have to ask:
the #1-#9 references are all with 7V output and the LTZ1000-1 through LTZ1000-3 are measured on the 10V output?
Or why is the jump larger for the lowest 2 devices?
Is there some linearity problem?
with best regards
Andreas
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That is correct Andreas, #1-9# are the raw 7.xV output while 1-3 are 10V output. Furthermore 1-3 are individually t.c. trimmed, while #1-#9 only have an initial 402k resistor installed.
-branadic-