Digikey Part Number | Manufacturer | Manufacturer Part Number | Customer Ref Number | Customer Description | Quantity for module |
N/A | Ultrohm Plus | N/A | R1-R5 | Custom made wirewound set | 1 |
495-2479-1-ND | EPCOS (TDK) | B32529C1104J289 | C1,C2,C4 | 0.1uF Cap Film 5% 100VDC | 3 |
495-2489-1-ND | EPCOS (TDK) | B32529C1223K289 | C3,C6,C7 | 22nF Cap Film 5% 100VDC | 3 |
399-3905-1-ND | KEMET | T495X476K035ATE300 | C5,C8 | 47uF Cap Tant. 10% 35V | 2 |
1N4148FS-ND | Fairchild/ON Semiconductor | 1N4148 | D1-D3 | 1N4148 Gen Purp DO35 | 3 |
PZT3904CT-ND | Fairchild/ON Semiconductor | PZT3904 | Q1 | Transistor NPN | 1 |
1.00KXBK-ND | Yageo | MFR-25FBF52-1K | R6 | 1k ohm 1/4w 1% | 1 |
10.0KXBK-ND | Yageo | MFR-25FBF52-10K | R7 | 10k 1/4w 1% | 1 |
1.00MXBK-ND | Yageo | MFR-25FBF52-1M | R8 | 1M | 1 |
402KXBK-ND | Yageo | MFR-25FBF52-402K | R9 | 402k ohm 1/4w 1% | 1 |
10.0XBK-ND | Yageo | MFR-25FBF52-10R | R10 | 10 ohm 1/4w 1% | 1 |
BC2299-ND | Vishay BC Components | NTCLE203E3103FB0 | R11 | Thermistor 10k | 1 |
LTZ1000CH#PBF-ND | Linear Technology | LTZ1000CH#PBF | U1 | Shunt Voltage Reference | 1 |
LT1013ACN8#PBF-ND | Linear Technology | LT1013ACN8#PBF | U2 | IC OpAmp | 1 |
HM1023-ND | Hammond Manufacturing | 1457K1202BK | N/A | Enclosure, Black | 1 |
HM1022-ND | Hammond Manufacturing | 1457K1202 | N/A | Enclosure, Natural | 1 |
1457K1202EBK-ND | Hammond Manufacturing | 1457K1202EBK | N/A | Enclosure, Black EMI Shielded | 1 |
1457K1202E-ND | Hammond Manufacturing | 1457K1202E | N/A | Enclosure, Natural EMI Shielded | 1 |
Test result description | Test setup | Datalog |
So I give them (management) a number, less than 0.3ppm/K. Or something. Buy me a better multimeter, then I will measure it for you..
Is there any benefit with using a conductive coating on it
When I was doing PPM measurements, with a 3458A, I could tell, when the last person left the office down to the minute.
I think eventually I measured a few. The methodology was:QuoteSo I give them (management) a number, less than 0.3ppm/K. Or something. Buy me a better multimeter, then I will measure it for you..
That's the good one, as there are not an awful lot of the voltmeters with tempco better than 0.3ppm/K :-DD.
My sub-millidegree res temp logger could easily determine the number of bodies in a somewhat large-ish lab (well, actually body-equivalents... one particularly obese person counted as two people) from the temperature gradient (BTW, one body equals around a 100 watt heater).Interesting. Is it a PT1000 with some 24 bit ADC or is it much more sophisticated than that?
You can get MuMetal foil even at Amazon these days, a little thicker like .005" is good. .01" works well also.
Don't make -sharp- bends in it...You can still see if it has a reduction effect for your situation with somewhat gentle bends. You might find that a good steel box alone works OK also - you just test and find out.You can get MuMetal foil even at Amazon these days, a little thicker like .005" is good. .01" works well also.
Is that good enough? I thought that after any mechanical processing (bending etc) mu-metal needs annealing which is done in hydrogen atmosphere. Heating pure hydrogen to 1000 deg C for hours is not something I would like to do at home.
My sub-millidegree res temp logger could easily determine the number of bodies in a somewhat large-ish lab (well, actually body-equivalents... one particularly obese person counted as two people) from the temperature gradient (BTW, one body equals around a 100 watt heater).Interesting. Is it a PT1000 with some 24 bit ADC or is it much more sophisticated than that?
Interesting. Is it a PT1000 with some 24 bit ADC or is it much more sophisticated than that?
custommagneticshielding.com has this product that doesn't require annealing after bending. http://custommagneticshielding.magneticshield.com/viewitems/mumetal-sheet-and-foil/mumetal-foil (http://custommagneticshielding.magneticshield.com/viewitems/mumetal-sheet-and-foil/mumetal-foil)
They mention that severe forming does not apply. They failed to mention what they considered severe forming. Is it making sharp bends to form a cover? Looks like a CYA catch-all.
I would consider using the adhesive backed foil and apply it inside a printed cover.
I'm just building another 4 new references, that's the successor of my prototype build, including supplements from Andreas design.
It's a single sided PCB, all leaded components, and it's compact, half size of the prototype, i.e. 50 x 80 mm, so four PCBs from one Euro-PCB.
That fits nicely in a small tuner box, which will be assembled inside another case.
T.C. compensation and 7=> 10V step-up amplifier will be trimmed next.
Anyhow, if you want to further improve your circuit, maybe you want to have a look on my solution.
I'm just building another 4 new references, that's the successor of my prototype build, including supplements from Andreas design.This awakes a great tension on what is announced now. :)
T.C. compensation and 7=> 10V step-up amplifier will be trimmed next.One question to that, because it is the next logical step to build a useful reference. Most referencepoints of DAC's ADC's need 5V, 4096V or something like this but <=5V. Maybe it's useful to have one of these voltages directly driven from LTZ (second) buffer too, or must it be 10V first? As you can see, this is my first attempt to build such things...
QuoteI'm just building another 4 new references, that's the successor of my prototype build, including supplements from Andreas design.This awakes a great tension on what is announced now. :)
Hopefully you have cap on top and bottom of LTZ.
I'm just building another 4 new references, that's the successor of my prototype build, including supplements from Andreas design.
It's a single sided PCB, all leaded components, and it's compact, half size of the prototype, i.e. 50 x 80 mm, so four PCBs from one Euro-PCB.
That fits nicely in a small tuner box, which will be assembled inside another case.
Inside the box? Simple i have two of these cotton make-up pads, one under, one over the LTZ.
Also make-up pads may be treated with who knows what.They are used, but i washed them. :-DD
I explicitly recommend Andreas design, especially the additional capacitors in parallel to each base-emitter diodes of the LTZ1000s transistors, that's C11 and C12 in his schematic.
It's definitely not true, that these capacitors affect the stability of the circuit, the opposite is correct.
I have added these two capacitors to my original prototype design from 2009 (it's in principle the datasheet circuit).
That greatly improved the EMI suppression, and the circuit shows no longer such spikes, even when a switch mode P.S.U. is present directly near the box.
Before that, the RF shifted the ovens set point and in turn the reference voltage (reversible change)
I don't think the rather small current noise and even the current peaks at the input of an AZ OP would be a problem for the LTZ1000 chip. These are just minute changes and thus should not be enough to really disturb the silicon. I won't be too much concerned about the silicon itself.
I think I might have been misunderstood and didn't explain very well - apologies: When I mentioned that caps can disturb the stability of the circuit, I should have said "degrades the stability of the LTZ die".
So: If you're going to run the LTZ circuit exposed to noise: on a bare exposed PCB without of a proper shielded enclosure - in a way that it was never intended - I can see that the extra caps on the LTZ pins would be a band-aid type of fix to hide some of those noise glitches. The problem with that is that it can increase the magnitude of current noise -across the LTZ die. The concern is the extra caps have provided a low-impedance reservoir of charge to allow higher LTZ peak noise current flow in response to external noise energy. Excess LTZ noise current is a direct contributor to degrading long term (> 5yr) stability of the LTZ die substrate, or cause the die to never quite achieve it's most relaxed, lowest energy crystalline state. The LTZ zener makes it's own noise for sure, but you -really- don't want to do anything to add to that.
If you're running a switcher power supply next to the LTZ circuit and those caps made the glitches disappear - you've certainly hidden the voltage glitches, but the LTZ die still is exposed to the current noise, which is not recommended. This is the same reason LT explicitly does not recommend a '2057 current driver with it's very high input current spikes injected onto the LTZ die if you're not careful.
Before Andreas complains, I know: The circuit will still work with AZ amp and extra caps of course - but if you want best long term stability for decades adding caps and/or AZ amps is not the recommended best practice. If you've tried every other way and the caps are the only solution for your application, then that's what you have to do...But there is probably something else wrong, like inadequate shielded enclosure or too much noise nearby in the lab. We would never, ever run a switcher power supply next a sensitive circuit during a measure, we always go to battery power for serious measures - Period. But that's how we have to do it for many more reasons than operating an LTZ.
Again - I've built several hundred compact boards, no slots or crop circles, and they go into well shielded enclosures, LTZ-A version soldered directly down onto the board, air-draft covered, and no real stability issues for decades. A working LTZ circuit will not generate random large output spikes on it's own. The circuit -itself- should NOT need those extra caps if you build it correctly, as per LT recommendations. They are the manufacturer and have a good source of long-term feedback data working with every major test equipment manufacturer - so I rely on their experience along with what I've witnessed for decades. That's all I can offer.
If you find the extra caps are required for your application, then you do what is required. For me I'd find the root cause of the noise first and deal with it at that level - remove the noise source or increase LTZ circuit shielding as required, quit making the board too big with long antenna traces, etc, etc, etc. That way you know you're protecting the LTZ die as much as possible from injected noise energy. You -never- want to throw caps at something like an LTZ to try to hide a voltage glitch that shouldn't be there if a better method is available. The "let's throw capacitors at the circuit until the output noise goes way" approach should be last line of defense for LTZ circuits, and usually indicates a bigger problem with the board design or enclosure - or lack of enclosure.
For sure, do what you need to that best works for your application - everyone has different needs.
Dr. Frank,
Thanks for sharing. I originally tried for that form factor but I wanted it to fit in an extruded enclosure which resulted in much less space along the two edges that fit in the slots. I agree with the dual resistor option for whatever parts are available.
I look forward to your build and testing of the multiple references.
You are probably correct on the high initial drift of my reference. There could have been excessive heat applied at soldering. I hope this one isn't a wash but it certainly won't stop me from building more. I sense my Ultrohm Plus resistors are not far from being finished and I would like to be ready with the next version. All options will be considered and I will add places for the extra film caps but I won't initially install them. They will at least be optional and won't need to be bodged into the board.
@ dr Frank,
I really interested about double shielding / guarding, like in Flukes calibrators but I have doubt about what exactly You talking about, can you tell / show a little bit about it.
The smart things are:
- single sided, so that all thermal junctions are on one side, and virtually at the same temperature.
- The layout is optimized for thermal symmetry, and all reference resistors and supplies are strung rigorously towards the two star points, -Ref and +Ref.
....The currents in the LTZ1000 circuit are not that small. Even the collector current of the transistors is at around 100 µA, and these nodes are not that sensitive to small voltage variations. So there should be no need for guard traces. The heating and thus usually slightly elevated temperature keeps humidity and thus leakage low too.
wouldn't guard traces be important to the uA level traces ? and since traces have no mask? or it doesnt matter as long it is cleaned and sealed?
The smart things are:
- single sided, so that all thermal junctions are on one side, and virtually at the same temperature.
- The layout is optimized for thermal symmetry, and all reference resistors and supplies are strung rigorously towards the two star points, -Ref and +Ref.
wouldnt guard traces be important to the uA level traces ? and since traces have no mask? or it doesnt matter as long it is cleaned and sealed?
For sure, do what you need to that best works for your application - everyone has different needs.
This is an area where theory ends and and reality begins.
At least the simulations show that adding capacitance at the transistors (base to emitter) reduces the phase margin. Together with capacitive loading this could go all the way to oscillation.
You need something of much more substantial thickness than a candy tin.
would 3mm be considered thick in your lab?
I am planning on adding a 3D printed cover for the board. Is there any benefit with using a conductive coating on it similar to how Keithley did their 2001/2002 design? MG Super Shield comes to mind but I wouldn't use it unless it is worth the investment.
For sure, do what you need to that best works for your application - everyone has different needs.
Hello,
these are true words.
But it is an illusion that you can keep out all EMI-sources even with the best metal housings
if you have a wide open door i.e. the reference negative line.
(it makes no difference if the positive reference line is buffered or not).
The best chokes have around 10 dB EMI reduction. (perhaps up to 20 dB if you have luck and the right frequency).
A capacitor easyly dampens > 20 dB if the wires are kept short.
So If you can switch off all EMI-sources during a measurement, can use shielded transformers which are hard to get in single quantities then its the best solution for you. But I fear most hobby volt-nuts do not have a shielded EMI-cabinet with multiple stage filters for the power supply.
So my needs are clear:
- I do not want to have different output values in my "lab" independent of the gear that I or my neighbour is using.
- I also do not want to have different readings when I take my references into a unknown environment e.g. for calibration.This is an area where theory ends and and reality begins.
So what do we have:
- no official documents from LT (no application note, no design note)
- no official published paper
- no measurement values nor a test setup to verify the story
On the other side:
I have recorded the ageing from my first 2 references over more than 6 years
there is only unusual ageing against other published papers of LTZ1000
if I short the output of the unbuffered reference.
-> Shi(f)t happens if you are working.
So what you describe (if it really exists) can only be a 2nd order effect.
with best regards
Andreas
Over n' Out. Have fun folks! Sorry if I've offended anyone here with advice & tips that has kept our equipment running to spec for some 30+ years, including LTZ's.
I am not a hobbyist, I make my living making sure high performance semiconductor devices perform to spec long after we're all long gone and forgotten. From manufacturing to packaging to final application.
At this end we've been helping our customers build longevity into devices for over 30 (35?) years, across hundreds of LTZ's for our own custom test gear - and that know how also goes into billions of devices you use every day
Over n' Out. Have fun folks! Sorry if I've offended anyone here with advice & tips that has kept our equipment running to spec for some 30+ years, including LTZ's.I'm at the other end, as hobbyist, that's not so vital to me, BUT, that's extremely grounded to me too, what you are talking about, and i understand every word that you mention here (ok, after some learning effect). I think, your input here is one of the best, and you're right! Others too, for sure. I understand, that must be very frustrating, if someone cannot go too deep in details to prove oneself, if others do because, maybe, they're not so legally bounded. But your sometimes opposite meaning is really an eyeopener to me and others, so, please keep doing that. :-+ :-+
At least the simulations show that adding capacitance at the transistors (base to emitter) reduces the phase margin. Together with capacitive loading this could go all the way to oscillation.
no.
you have overlooked that loop stability is maintained by a additional 10K (in series to negative OP-Amp input) + 100nF across the Op-Amp
in Franks and my cirquit.
Opposite to your assumption the simulation shows more overshoot with the original AN86 cirquit than with Franks design.
Of course the original AN86 cirquit will oscillate with a load capacitance of more than some nF.
with best regards
Andreas
Thanks. I try to give as much detail as I can but I really have to stay out of trouble with customers, and I have to not mention the company name. The end result here is sometimes it looks like a wishy-washy answer pulled out of my butt I know - and sometimes it's better if I just stay quiet. I have to respect our customer's respect for keeping their R & D private; so sometimes I just have to observe here, and toss out a tidbit only if it's common helpful knowledge.
I understand a hobbyist has budget restraints, but that means you get creative and learn.Or move the restraints, but that does little good actually, leading to equipment hoarding issues with zero knowledge learned. :-DD
Or move the restraints, but that does little good actually, leading to equipment hoarding issues with zero knowledge learned. :-DD
Or move the restraints, but that does little good actually, leading to equipment hoarding issues with zero knowledge learned. :-DD
I am making a storm shelter out of my gear. I hope I don't have to find out if any of it floats.
Have you ever heard of an NDA?
Or move the restraints, but that does little good actually, leading to equipment hoarding issues with zero knowledge learned. :-DD
Hello MisterDiodes,
don´t take it personally.Have you ever heard of an NDA?
Of course, but that´s not the way a public forum is working.
And usually on important things the NDA is running out as soon as the patend is claimed.
If you say throwing capacitors is a "no no" you should be able to explain that.
I get the impression that with your statements some of the members are insecured somewhat.
And I can not estimate if it is really worth that.
with best regards
Andreas
The way NDA works is that you get resources and honor to acquired knowledge to be kept private between the involved parties.
Also the way public forum works is anything published is up to poster discretion. Be it accurate or not, complete or not, up to the poster, and nobody else. It's also better be safe than sorry, and stay out of sensitive subjects, no matter how much we would love to see the data.
Surely MD will be happy to offer you full details and certificates and test data results, if you become his customer and pay all that research and time, and likely you would wish that data not to be freely distributed for anyone else, undermining your product advantage. :)
I'd suggest we leave this OT at this, and move on :-DMM.
After all any of our data or results posted (including yours, with all due respect) are yet to be proven to be the only "hard rock solid truth". I don't see issues with my AZ modules without extra caps, nor I see any improvement with the caps. But that only means it works for my specific case, in my specific environment, and with my equipment, and those few references for hobby voltnutting purposes only.
The way NDA works is that you get resources and honor to acquired knowledge to be kept private between the involved parties.Yes thank you. I also made a design for the LTZ1000, few hundred was built, tested, calibrated and shipped. And I had a lot of data about it, a lot that I produced myself. Under NDA. And though my NDA is not applicable anymore, I dont feel like I should be going around and spreading the info that I have. I could from memory, re-draw the schematic, aproximate the PCB, and open source it, or even start selling it.
Also the way public forum works is anything published is up to poster discretion. Be it accurate or not, complete or not, up to the poster, and nobody else. It's also better be safe than sorry, and stay out of sensitive subjects, no matter how much we would love to see the data.
Surely MD will be happy to offer you full details and certificates and test data results, if you become his customer and pay all that research and time, and likely you would wish that data not to be freely distributed for anyone else, undermining your product advantage. :)
I'd suggest we leave this OT at this, and move on :-DMM.
After all any of our data or results posted (including yours, with all due respect) are yet to be proven to be the only "hard rock solid truth". I don't see issues with my AZ modules without extra caps, nor I see any improvement with the caps. But that only means it works for my specific case, in my specific environment, and with my equipment, and those few references for hobby voltnutting purposes only.
The LTZ1000 datasheet Page 6 that is currently online right now - that cap shown on Non-inverting input of '1013 is .022uF...NOT .002 uF as shown.
Side question to fellow LTZ enthusiasts. How much value there is in ovenizing (i.e. not only insulating but putting a heater as well) the reference board? In Fluke references it is obvious as LTFLU doesn't have a heater, but LTZ1000 does and the surrounding resistors have something like 0.01 factor impact on the output value. I'm planning to have 13k/1k resistor ratio, therefore AFAIR 55 deg C so the oven temperature would need to be be below that to allow LTZ heater operation and that would get close to room temperatures in the summer.
I'm asking because originally I was planning to design LTZ + LT1013 + other page 6 bits mini-module, very similar to shape and form factor to the 3458A reference, but inside a case filled with Spacetherm insulator. No oven. Then on another mini-module I was planning to have 10V step up and VHP202Z 10k (I want this modules to be 10V and 10kOhm standards) - this mini module would be similarly insulated, but also ovenized to 55 deg C, this could age the resistors slightly faster but would provide better stability. Overnizing only the second mini-module would bring the power consumption down which is important as I want this to be powered by 4x18650 cells.
I've ordered VHD200 10k/25k dividers from eBay for the 10V step up and I'm thinking if I should provide any means of adjustment at all. This divider in the non-inverting configuration would bring LTZ voltage 6.9-7.5V to 9.66-10.5V, close enough for any equipment that would need ~10V and adding extra parallel/series resistors/trimmers could be detrimental, I will be happy with just this divider and whatever value it settles onto and let it age. But on the other hand adjustment capability would allow nulling to another 10V standard, instead of just measuring my standard with e.g. 3458A which is less accurate. Any opinions?
It makes no sense to ovenize the LTZ1000 board.
That would only lead to problems with the LTZ1000 own oven stability.
And as you already mentioned, the influence from the 5 precision resistors is only 1/75 , down to 1/1000.
Typically, you'll end up with about +/-0.05ppm/K overall.
And it's much easier, to use compensation methods to bring the overall T.C. to around 0.01ppm/K.
If you put the step up resistors in an isolated oven, that would make sense, as this is the main feature of the 732A/B circuits, to have a low T.C. for the 10V output also.
Obviously, you're planning to build the very same solution/form factor, which I have published here, a few days ago.
I decided to provide a trimming to exactly 10.000V, for usage in a precision Bridge configuration, where it's more convenient to have a 'round' value.
The trimming does not affect the stability of this amplifier circuit, and you can also omit that and just live with odd values.
Well, you can still order a custom resistor from Vishay Foil. In fact, if I would be volt nutting at home, I would do that. The S series has some 0.2ppm tracking, and the two resistors in one package. It will be for sure expensive, about an LTZ1000 brand new. They trim it to 6 digit. Just build the reference, burn it in, measure the value, and custom order the precision divider to get the 1-2ppm accurate 10V reference. If you really really want, trim that with a million turns pot.
You should definitely talk to sales manager of your region from Vishay foil. On phone.
Similar, but I wanted separate 3458A-like ref module, so I could use that elsewhere (I want to build a variable resistance standard, based on Valhalla 2724A, like Mickle T did) and separate step-up/10k standard in the oven.
I have parts to build 4 (and 1 extra ref-module), so the final version will be a DIY Fluke 734A. I need to find a suitable case that would fit a toroidal transformer for charging and PCB slots to slide the modules in.
So my layout allows to cut off the amplifier part, and get a 57 x 50mm PCB, similar size like in the 3458A (48x41, I think), but with space for PWW resistors.I was thinking about something like that, I think at seeedstudio they call it self-panelization, but because of the many mechanical components involved in the mini-module covers (steel sheet, spacetherm, kapton, nylon standoffs) or oven (heater - TBD, some resistive foil to test on order) I think I'll have 2 separate designs.
Anyhow, the design of an isolated, silent, 4 fold PSU would be great.. much more important than YaRM - yet another reference module..Yeah, I was thinking about that initially, some form of Royer followed by low noise LDO and a lot of ferrites everywhere. My analog foo is probably not good enough for that and it is a lot of work.
Yes, 1mm ~ 3mm would be a good place to start. We use .05 or .0625" as a starting place if you're on imperial measurements. The inner box can be slightly thinner, and maybe a single box is all you need. We normally go for a 1/4" spacing between inner and outer but 1/8" would probably be OK. It depends on what you're shielding from. Aluminum will help some against E-fields but not much for mag field issues.
Also note: If you're using PWW resistors it's important to at least have some minimal shielding around your circuit if you're near stronger H-fields - say an industrial area where you've got power mains in conduits, motors, ovens, etc. Those resistors are wound with balanced windings but they will see some magnetic interference effects in a strong field unless you give them at least some protection - otherwise they will give you low noise performance.
Received several sets of resistors from Edwin on Thursday. Thank you Edwin!