Ian Johnston PDVS2

[The Soulman]

You don´t have to buy it.  So why complain about anything. 
Nothing comes for free, not even wifi.

[Free_WiFi]

You don´t have to buy it.  So why complain about anything. 
Nothing comes for free, not even wifi.

Im not really complaning about the Ian Johnston's unit.
Here im just saying that this unit is too much expensive for the single Voltage function.
However if there was more funtions like :  µA and mA then i will be ready to buy it also now!
I have tons of old multimeters in my house and a lot of them can be calibrated by the internal trimmers;
in these days im trying to find some regulable device like this one ,just with a little bit more functions like i said before.
For example the Pentaref from : www.voltagestandard.com is a nice unit ,but i can't play with the reference output like on the Ian Johnston's unit.
In these days i also planing to buy for my self an multimeter ,like the : VC890.
This multimeter is digital and can be calibrated by the internal trimmers,so if i will buy the Ian Johnson's unit (But with more functions) then i will be able to mantain my brand new DMM... and any other DMM like my old MetraGossen 24s ,26s etc....
I wish the best for Mr.Ian Johnston,also that maybe one day he will be able to create an project dedicated for home made calibraition and mantening of ours DMM's.

[Gyro]

You are reading and posting in the Metrology section here - it is about highest achievable precision, not hobbyist DMMs level.

For Hobby DMMs you would be better to look in the Beginners or Test Equipment sections. 

I feel some kind of hostility smell against me,but why ?
Im just getting out my personal opinions.
In my opinion this device is very expensive without functions like µA,mA and + you're super pathetic if you really wanna tell me that this is some kind of professional instrument for calibration or reference ... 
I don't think and i also won't to believe that a real professionals will use this expensive black box toy in the real professional fields of metrology ... 
So please... keep kalm and love your toys ,im also not blaming someone or something ,this black magic box is still pretty cool,but damn !!! is very expensive and of course is not for professional purposes like you are trying to make me to believe in it 

Well congratulations for getting the most emoticons in a post for a while.

I certainly meant no hostility towards you. I was reading your post in conjunction with your "My first "Pro" handled DMM" thread. The questions you were asking there would have received more response and been more appropriate in the Test Equipment section - more helpful to you. The Metrology section is where (to quote the section description) 'the Voltnuts hang out', threads tend to be about getting best performance out of xxx voltage reference, new reference ideas, TC of precision resistors etc. so 'what DMM should I buy?' type questions don't really get much attention. Maybe I should have spent more time writing a longer reply but I was hoping I didn't need to.

For the record, Ian Johnston is shooting for way above the sort of performance you get from your average DMM check type product...

you're super pathetic if you really wanna tell me that this is some kind of professional instrument for calibration or reference ... 

... So there's no need to be insulting about it! 

[Free_WiFi]

For the record, Ian Johnston is shooting for way above the sort of performance you get from your average DMM check type product...

Lol ,pls someone call the Captain Obvious.....
I already knew that this unit is very precise etc ... but the lack of some missing features,are making this buy deadly for any wallets (maybe not for yours..)
However would be really nice to re-work or just implement the µA and mA ranges to make this device really the top of the top on the entire Voltage reference scenario.
And pls ,be honest ,because there are more hobbyist then professionals which are or would be interested in this pocket unit.

[Alex Nikitin]

I already knew that this unit is very precise etc ... but the lack of some missing features,are making this buy deadly for any wallets (maybe not for yours..)
However would be really nice to re-work or just implement the µA and mA ranges to make this device really the top of the top on the entire Voltage reference scenario.
And pls ,be honest ,because there are more hobbyist then professionals which are or would be interested in this pocket unit.

As already has been pointed out, this area for people looking for ppm-level errors. For it's performance Ian's unit is actually inexpensive. Heck, I've paid more than that for a single 10K resistor (and planning to spend another £200 just to get it measured accurately)! To provide a current output with a similar kind of errors would probably double the price of the unit!

Cheers

Alex

[Free_WiFi]

As already has been pointed out, this area for people looking for ppm-level errors. For it's performance Ian's unit is actually inexpensive. Heck, I've paid more than that for a single 10K resistor (and planning to spend another £200 just to get it measured accurately)! To provide a current output with a similar kind of errors would probably double the price of the unit!

Cheers

Alex

Oki.
So where i can find a unit which basically can do the same stuff like this one ,but with more functions like the µA and mA ranges ?
I've not yet found this DIY-reference with the same capabilities of Ian Johnston's unit + µA and mA ranges,so what i can do to get something similar to my needs ?

[Alex Nikitin]

Oki.
So where i can find a unit which basically can do the same stuff like this one ,but with more functions like the µA and mA ranges ?
I've not yet found this DIY-reference with the same capabilities of Ian Johnston's unit + µA and mA ranges,so what i can do to get something similar to my needs ?

To discuss it here would be off-topic, you should really start another thread, stating your requirements (including ranges and error levels).

Cheers

Alex

[2N3055]

So where i can find a unit which basically can do the same stuff like this one ,but with more functions like the µA and mA ranges ?
I've not yet found this DIY-reference with the same capabilities of Ian Johnston's unit + µA and mA ranges,so what i can do to get something similar to my needs ?

That sort of device is called multifunction calibrator... And they cost a lot...
But as Alex said, if you have something specific in mind, write up a specification, and post a topic with a question.

[Free_WiFi]

That sort of device is called multifunction calibrator... And they cost a lot...

:)i knew the name of this device ... however i can't afford an real multicalibrator,
but as soon i will post my topic about my request .

[WackyGerman]

So where i can find a unit which basically can do the same stuff like this one ,but with more functions like the µA and mA ranges ?
I've not yet found this DIY-reference with the same capabilities of Ian Johnston's unit + µA and mA ranges,so what i can do to get something similar to my needs ?

You don t find it because it s not built yet . You only can buy super accurate voltage references or current references

That sort of device is called multifunction calibrator... And they cost a lot...
But as Alex said, if you have something specific in mind, write up a specification, and post a topic with a question.

Yes they cost much more than Ians PDVS2 but only have an accuracy of 0,02 % so you cannot compare it to the PDVS2

[IanJ]

So where i can find a unit which basically can do the same stuff like this one ,but with more functions like the µA and mA ranges ?
I've not yet found this DIY-reference with the same capabilities of Ian Johnston's unit + µA and mA ranges,so what i can do to get something similar to my needs ?

That sort of device is called multifunction calibrator... And they cost a lot...
But as Alex said, if you have something specific in mind, write up a specification, and post a topic with a question.

Time Electronics Model 1044 (they've been making these for years and years)
https://www.timeelectronics.com/portable-voltage-current-instruments/1044-voltage-and-current-calibrator/
Cost = £510.40 from RS
However, I wouldn't trust it to calibrate my DMM's in all honesty. Check them for basic functionality maybe, but certainly not calibrate them.
Btw, every time I look at the cost of the 1044 I think my PDVS2 is being sold too cheap....:-)

If anyone wants something with a better spec than the 1044's 150/200 ppm/degC and 0.02% (if I remember correctly) and with all the functionality then it's just not going to happen without paying for it.

End of day though, I am sorry to Free_Wifi that my unit doesn't have uA or mA......it's maybe something for me to think about for the future.

Ian.

[hwj-d]

Btw, every time I look at the cost of the 1044 I think my PDVS2 is being sold too cheap....:-)

Then, don´t think about this 1044 too much 
Some people in the world can´t really hold well old scottish stuff 

Thank´s for your PDVS2. Don´t have one, but learned much...

[2N3055]

So where i can find a unit which basically can do the same stuff like this one ,but with more functions like the µA and mA ranges ?
I've not yet found this DIY-reference with the same capabilities of Ian Johnston's unit + µA and mA ranges,so what i can do to get something similar to my needs ?

You don t find it because it s not built yet . You only can buy super accurate voltage references or current references

That sort of device is called multifunction calibrator... And they cost a lot...
But as Alex said, if you have something specific in mind, write up a specification, and post a topic with a question.

Yes they cost much more than Ians PDVS2 but only have an accuracy of 0,02 % so you cannot compare it to the PDVS2

There are many devices, including for instance Fluke 5730A High Performance Multifunction Calibrator , that have specs much better than that... With vertigo inducing price...

Ian did fantastic job with PDVS2. For the price, there is nothing out there with similar specs..

[Free_WiFi]

I am sorry to Free_Wifi that my unit doesn't have uA or mA......it's maybe something for me to think about for the future.
Ian.

Thanks you very much!!!
Im alway here to check up the progress of the development of your fantastic unit,because i really like it .
However when my dream about uA and mA become true then i will also buy it as fast as possible 


Guaranteed!!!

[feedback.loop]

I am sorry to Free_Wifi that my unit doesn't have uA or mA......it's maybe something for me to think about for the future.
Ian.

Thanks you very much!!!
Im alway here to check up the progress of the development of your fantastic unit,because i really like it .
However when my dream about uA and mA become true then i will also buy it as fast as possible 


Guaranteed!!!

Are you looking for a pocket size calibrator only? If not, then, perhaps, something like EDC 520 can be of use. They can be found quite cheap. Especially if you don't mind repairing them.
https://www.eevblog.com/forum/metrology/edc-520a-repair/

[hwj-d]

when my dream about uA and mA become true

Don't dream, this is EEVBlog. Make it by yourself. 

Ian Johnston shows in detail, how to do that. Really, what do you want more?
For constant current, maybe, go and look for YT Scullcom.

I wish you good luck for that. 

 

[Free_WiFi]

Don't dream, this is EEVBlog. Make it by yourself. 

Ian Johnston shows in detail, how to do that. Really, what do you want more?
For constant current, maybe, go and look for YT Scullcom.

I wish you good luck for that. 

My dreams will be dreams for long time yet.
I can't play around precision things ,because actually i can't afford an bench multimeter for $1.000   
So if my situation wasn't like it's now ,then i will be able to done something alone.
Im poor ass,so for now i just can dreaming to create something like the  Ian Johnston's unit 
However ,thanks you for the best wishes.

[hwj-d]

My dreams will be dreams for long time yet.
I can't play around precision things ,because actually i can't afford an bench multimeter for $1.000   
So if my situation wasn't like it's now ,then i will be able to done something alone.
Im poor ass,so for now i just can dreaming to create something like the  Ian Johnston's unit 
However ,thanks you for the best wishes.

Yes, i know that from my own in the past, and i'm by you.

The point is, it's not coming from one moment to the other. If you want to make it by yourself, don't set your momentary expectations too high. There are some chips, they have a good accuracy and TC from the beginning, as REF5010 or more DAC-compatible REF5020, -40. For this, you need only two capacitors and a through-hole platine (no breadboard, in this case) to get your own Ref's. Go or send it to someone, who owns a good in spec DMM to verify it at 10x. Then you have your first basis, to check your next things.

After that buy a couple of good TC resistors and OP's like this LTC1152. Take for the beginning through-hole variants if possible, or take this little adapters. Take some DAC's and play with it. Look for the good stuff from Digikey, as an example, they send it for free from US to you, if you have an 50$ order. From China, Banggood as an example, you get the basic material for cheap, if you can wait a month, arduinos, breadboards etc. (Edit: From germany, each order not more than 25-30EUR, to prevent tax)

So, things comes together. If you need better measurement tools, you will know it AFTER, or in the moment you make things. A good DMM, maybe a cheap scope for the beginning, is ok. But don't buy something expensive on suspicious. Wait and see, what you really need.

HTH,
 

[IanJ]

Hi all,

I am now out of stock of PDVS2's, so if there's now an opportunity to tweak the hardware design a little then it's now before I order parts for the next batch......

I can add a DCI output pretty easily.......I've been breadboarding the changes necessary and it seems like it is doable without raising the cost by much at all.......but I'd like some feedback on usefulness of such a function.

There would be a 3rd banana socket to facilitate the DCI output. Totally load independant from 0ohm to xxxohm yet to be determined.

0 to 4mA range, in the order of 0.1uA or 1uA minumum resolution, so if we say 1uA then that would be X.XXXmA.

Is 4mA too much, how about 1mA max.......I'm pretty open here just as long as it's no more than 4mA.

EDIT:
2mA max is nice, works out great.

Ian.

[The Soulman]

10mA? Could be useful for 4 wire low value resistance measurement using a "normal" dmm.
That would also work with 1mA obviously.

[2N3055]

Hi Ian..

most people have trouble sourcing very small currents... Like _uA level.. For instance, lets say I want to check if uCurrent is accurate.. Or my DMM 400_uA range..
Most better PSU will be good enough to source 100mA, but sourcing 10_uA is not easy in hobby lab..

Ideally you should go to 100mA, but I imagine, that's not easy for your architecture as it is now (battery supply and such).
But adding very small currents might be useful ..

[MisterDiodes]

Nice project Ian!

For the suggestion box: If you're thinking about adding a current range function, it would be great to have a relatively accurate 4, 10, 16 & 20mA output for testing 4-20mA loop readouts and controller / sensor control loop inputs.  That's always a handy feature to have.  Some devices will be 100% full scale at 16mA, others will use 20mA to indicate full scale.  I would suggest at least 12V compliance voltage if possible, or more.

Since you already have an adjustable Vout, it's not a huge leap to make a fairly accurate Iout driver as well, probably across a few ranges.

[nour]

What about making two ranges, from 1 uA up to 1 mA by 0.5 uA incrementing and from 1 mA up to 10 mA by 1 uA incrementing!

[IanJ]

Nice project Ian!

For the suggestion box: If you're thinking about adding a current range function, it would be great to have a relatively accurate 4, 10, 16 & 20mA output for testing 4-20mA loop readouts and controller / sensor control loop inputs.  That's always a handy feature to have.  Some devices will be 100% full scale at 16mA, others will use 20mA to indicate full scale.  I would suggest at least 12V compliance voltage if possible, or more.

Since you already have an adjustable Vout, it's not a huge leap to make a fairly accurate Iout driver as well, probably across a few ranges.

My background is in instrumentation so have used 4-20mA a lot......and to tell you the truth if I were to implement it then it would need to sink as well as source the current so this adds in another level of complexity not to mention the changes I would need to make to the power supply side in order for it to cope,not to mention the cost. I'd really like to implement it but I don't think it will happen on this unit if I'm honest.
I will study it a bit more though.
Ian.

[hwj-d]

And the next step after the next step is to precisely measure sink and source up to 3A....