General Question

[GEOelectronics]

Thanks for starting the thread Tomato.

(joke removed by author)

George Dowell

[Conrad Hoffman]

I spent much of my previous job building interferometers of various types and doing "machining" that many would say is impossible.

hello Sir,

would that be precision-lapping by any chance?

forever grateful to you.

-zia

Honing of round parts actually. We built piezoelectric motors that required a fit within 10-15 millionths of an inch of a certain target. With a well tuned Sunnen machine and the right air gauging, it can be done quickly and in reasonable quantities. The optics for the big Fabry-Perot interferometers were purchased from the UK and would pair up for lambda/200. I think telescope people get all excited if their secondaries get to lambda/20.

[GEOelectronics]

Tomato, Frank's site explains one of the main reasons to have a Voltage reference in an electronics shop very well:

http://www.frankshospitalworkshop.com/electronics/diy-voltage_reference.html


George Dowell

[kj7e]

Threads about voltage references seem to dominate this forum.  As a general question, why is everyone interested in this?

In order to measure anything, you have to start with a known reference.  I have always found "the volt" very interesting, the history and why 1 volt is... 1 volt.  Who and why did they decide this specific amount of EMF will forever forth be known as 1 volt.  I asked this question to a Ham Radio friend of mine with I was just getting in to radios and electronics as a kid.  A few dozen questions later he told me I needed a Standard Cell (which lead to a few dozen more questions).  Dr. Frank had a nice post here regarding the history of the Volt;
https://www.eevblog.com/forum/metrology/1000-my-(hi)story-of-the-weston-cell-of-the-volt-and-of-being-a-volt-nuts/

Its amazing to me, how precise we can get, but at the same time it still seems there is so much uncertainty and how difficult it is to achieve any greater precision and or accuracy.  The best voltage reference (not counting a JJA as that cant be practicality owned)  to date was developed 33 years ago and its not been improved upon since.

[hwj-d]

Threads about voltage references seem to dominate this forum.  As a general question, why is everyone interested in this?

Take one or more of those answers:
First: yes
Second: don't know, what others ("everyone") are thinking
Third: ask a locksmith, why he is interested in his vernier calipers
Fourth: we are all going to need "splitting ball hairs"[sic! mjlorton(yt)]
Fifth: build one, to find correct answers

HTH 

[tomato]

I have bought every book on metrology I have come across, so it is now approaching 6 ft of books. 

Can we assume you meant to write 6 m of books?

[tomato]

A voltage reference is the "hello world" of metrology

Yes, that makes sense - it's cheap and easy to get your feet wet.

[JS]

Because you need to know the 8th digit,
to calibrate your 7 digits instruments,
to calibrate your 6 digits instruments,
to calibrate your 5 digits instruments, 
to calibrate your 4 digits instruments,
to calibrate your 3 digits instruments, 
to meassure a voltage at ±10% of the PS of a TV and say the it should be working but still doesen't   

JS

[GEOelectronics]

Because you need to know the 8th digit,
to calibrate your 7 digits instruments,
to calibrate your 6 digits instruments,
to calibrate your 5 digits instruments, 
to calibrate your 4 digits instruments,
to calibrate your 3 digits instruments, 
to meassure a voltage at ±10% of the PS of a TV and say the it should be working but still doesen't   

JS

I came to this sub group of metrology to learn new (to me) and better (than I have been using for 50 years) techniques of electronics measurements, expecting discussions about bridges, instrument amplifiers, filters etc. etc. etc.
Your explanation sums up the majority of the preferred subjects nicely.
I go away with the feeling that there are three things in Metrology, HP3458 and LT1001 and $75 resistors.
Nothing else matters or is allowed.

My article about a 0.03% resistor box was met with "Put some better resistors in there".
My hack to a China LM399 board's response was "why bother".
My question asking was there a mid level metrology board somewhere got no response at all, however there is one somewhere, or will be soon
Respectfully, but not impressed,
George Dowell

[kj7e]

George, I read your posts you reference.  I did not have the same takeaway you mention.

Even though most all posts here are in English, this is a very international forum and context is not always translated well.  I have seen some responses that come off harsh but really are not meant to be (lost in translation).  Also, particularly with the metrology group, its always about how can something be done better.  So yes, anything posted here will be critiqued and criticized in the effort to improve whatever the desired outcome is. 

[Vgkid]

@ George Dowell , an I have a link to your decade box thread.

[GEOelectronics]

Thanks L+N, there are several other one page articles in the works concerning the L&N "Boxes" of various model #s. Some have milliohm resistors that can be used as references and others have quite a few wire-wound resistors that look particularly hack-able.

Now that I can measure milliOhms for the first time, with 2 instruments, one a vintage HP-analog and the other a modern digital, I've been having a ball measuring things  that were unimportant in my business and hobby before Not that I get paid to or need to, it's just a hobby now.

Those will be published on eHam along with a homage to William Edward Ayrton


Geo

[TiN]

I go away with the feeling that there are three things in Metrology, HP3458 and LT1001 and $75 resistors.
Nothing else matters or is allowed.

I can excuse your statement, due to fresh member effect  . Proper phrase should be "three things in metrology, Fluke 792A, Fluke 734A and ESI SR104". Truckload of rest M$ gear is expected as default. 

Jokes aside on serious note, I don't quite see that much members here to bloat on having 3458A(/8508A/5730A/XXXXA/whatnot else) , like you suggesting to grant the "must have 3458 or you are not worthy" attitude . It is probably just biased because people here (in metrology section of the EE forum) are biased and sucked into this hobby, so on average more of us have expensive meters, than usual electronics engineers, who don't need such meters for daily work.

If you looking for feedback on low-cost projects, that is fine too, if you don't take too everything that people post too personal. After all it's only this much once can do with low-cost part, that is designed and manufactured to meet it's spec (usually, take that VPG , but it's bit much to ask for much better. Some go to great length doing sorting/matching/baking/cooking/soaking low cost part, be it resistor or voltage reference chip, but in the end it would be financially, time-wise and project wise CHEAPER just to spend those $5-75-250 on higher spec part that designed as such and not to worry. Now some of high-priced parts have issues and limitations too, so entering into realm of testing those limits and how to live with them is bit another matter, as it may help us to understand how to make things better. It is what some of nuts here about, taking something best commercial market can offer, and attempting futile attempts trying to go step above. 

Remember, lot of us here doing metrology toys and builds at home as a hobby, just for own amusement in free time, and often that extra hour of free time spent on soldering, measuring and documenting (taking photos and making post like this take time too!) is more expensive than even 75$ resistor. So think about return factor, what you are after, it is always a choice somewhere.

So yes, anything posted here will be critiqued and criticized in the effort to improve whatever the desired outcome is.

This! Also we already have General electronics talk, Test equipment, Repair and Projects sections. I see no reason why need to turn Metrology section into mix of these, posting general questions.
Back when I joined EEVBlog forums, all volt-nuts/ohm-nuts/time-nuts just hang out in T&M section and repair section, making all meaty threads that might be of interest for *nuts, but not so for general EE folk sink into abyss quick.
As refining Dave created dedicated subsection so bees are happy and separate from wasps and hornets now. So this supposed to be high-SNR area from the start, and members expected to have some level of understanding of things discussed.

[GEOelectronics]

Back when I joined EEVBlog forums, all volt-nuts/ohm-nuts/time-nuts just hang out in T&M section and repair section,

Finally the answer to my very first questions, thank you.
By the way tin, are you an administrator/moderator/owner here?

Geo

[TiN]

No, I'm mere humble contributor 

[Vgkid]

Thanks L+N, there are several other one page articles in the works concerning the L&N "Boxes" of various model #s. Some have milliohm resistors that can be used as references and others have quite a few wire-wound resistors that look particularly hack-able.

Now that I can measure milliOhms for the first time, with 2 instruments, one a vintage HP-analog and the other a modern digital, I've been having a ball measuring things  that were unimportant in my business and hobby before Not that I get paid to or need to, it's just a hobby now.

Those will be published on eHam along with a homage to William Edward Ayrton


Geo

That's right. I remember seeing your post on the "Ayrton Shunt does Double Duty" on the volt nuts mailing list. I have a relative of that box , the 4385
https://www.eevblog.com/forum/metrology/ln-4385-teardown/
along with a 4232 Wheatstone Bridge
https://www.eevblog.com/forum/metrology/ln-4232-wheatstone-bridge/
A 4393 URS, I plan on buying another one once I get a real job , and gutting both of them...
https://www.eevblog.com/forum/metrology/ln-4393-universal-ratio-set/
and a 4271 linear amplifier , that doesn't seem to work correctly. It will be stable for several days , then go drifty. Unfortunately it is unstable.
When it comes to milliohms , that is also one thing that greatly interested me as well.

[cellularmitosis]

I came to this sub group of metrology to learn new (to me) and better (than I have been using for 50 years) techniques of electronics measurements, expecting discussions about bridges, instrument amplifiers, filters etc. etc. etc.

I would love to see posts about this, or youtube videos!  This would be fantastic.

My article about a 0.03% resistor box was met with "Put some better resistors in there".
My hack to a China LM399 board's response was "why bother".
My question asking was there a mid level metrology board somewhere got no response at all, however there is one somewhere, or will be soon
Respectfully, but not impressed,
George Dowell

It can be easy to get discouraged on the internet, because the voices of detractors can be so loud, especially relative to the silent majority who are interested in such posts and eagerly awaiting more.

I was enjoying your posts so far, I hope you keep chugging along! 

[rhb]

I came to this sub group of metrology to learn new (to me) and better (than I have been using for 50 years) techniques of electronics measurements, expecting discussions about bridges, instrument amplifiers, filters etc. etc. etc.
Your explanation sums up the majority of the preferred subjects nicely.
I go away with the feeling that there are three things in Metrology, HP3458 and LT1001 and $75 resistors.
Nothing else matters or is allowed.

My article about a 0.03% resistor box was met with "Put some better resistors in there".
My hack to a China LM399 board's response was "why bother".
My question asking was there a mid level metrology board somewhere got no response at all, however there is one somewhere, or will be soon
Respectfully, but not impressed,
George Dowell

I made a partial list of my ongoing projects this morning:

DIY RF power sensor

OSHW diode noise source

Reference aging study using <$3 AD584s from eBay

VNWA 3E S parameter test fixture

Arc second electronic level

Multiplexed sampling system

TEC environmental test chamber

Gauge block interferometer

Monochromatic light box

All of these are fundamentally metrology projects, but except for the AD584 project, none of them are voltage reference related. And there are interdependencies among them.  I need the multiplexer to do the AD584 project.  But none of these involve a high end DMM , voltage reference or resistor. I have lots of equipment and measuring tools.  I'm trying to acquire the ability to maintain and calibrate them.

Some people in the forum are very narrowly focused.  Many others are much more broadly focused.

[kj7e]

I came to this sub group of metrology to learn new (to me) and better (than I have been using for 50 years) techniques of electronics measurements, expecting discussions about bridges, instrument amplifiers, filters etc. etc. etc.

I would love to see posts about this, or youtube videos!  This would be fantastic.

I was enjoying your posts so far, I hope you keep chugging along! 

Jason,
http://www.qsl.net/k0ff/

Lots of cool stuff there.

[GEOelectronics]

That's right. I remember seeing your post on the "Ayrton Shunt does Double Duty" on the volt nuts mailing list. I have a relative of that box , the 4385
https://www.eevblog.com/forum/metrology/ln-4385-teardown/
along with a 4232 Wheatstone Bridge

[/quote]

Thanks for those links. So far in the collection and have been torn down are  2 different  "Volt Boxes" "Shunt Boxes" and the "Ayrton Shunt Box".
Cat 7592 Volt Box
Cat 7593 Volt Box
Cat 4385  Shunt Box
Cat 4385-S Shunt Box
Cat 2664 Ayrton Shunt Box.

Were there others?
Also is there an archive holding L&N manuals/schematics/ads etc?
I saw your teardown of the LN ratio bridge, thanks for that it answered all my questions about that device.

Perhaps we should pick this up in PRODUCTS sub category now that I have found it (not what I thought was in there).

Geo

[GEOelectronics]

George, I read your posts you reference.  I did not have the same takeaway you mention.

KJ7E- I mean no criticism of your recent resistor standard project posts, I envy them.

I'm building one with a $5.00 eBay resistor. And another with a $10 USD eBay resistor.
Please comment

.

By the way can anyone identify the connectors that came on these? They are 0150" OD.

http://www.qsl.net/k/k0ff/VOLT_NUTS/DIY_0.01%25_and_0.005%25_Resistance_Standards/PicFile/

[kj7e]

No worries here George, I just meant I don't think people where being overly critical of your posts.

If you want to have some fun, test those parts for TC.  Its really eye opening.

[GEOelectronics]

Yes TC is on top of the bucket list.

Geo

[GEOelectronics]

The best link is :

http://www.qsl.net/k/k0ff//VOLT_NUTS/

Geo

[JohnnyMalaria]

Tomato, Frank's site explains one of the main reasons to have a Voltage reference in an electronics shop very well:

http://www.frankshospitalworkshop.com/electronics/diy-voltage_reference.html


George Dowell

That's interesting. I'll open the back of a couple of mine

But I have what I hope isn't a dumb question: if it's so straightforward to construct a reference from a few inexpensive components, why don't DMMs have internal references? (Maybe the top-notch ones do?)