Ian Johnston PDVS2

[kj7e]

Just pulled the trigger, the waiting begins...

http://www.ianjohnston.com/index.php/onlineshop/handheld-precision-digital-voltage-source-v2-detail

[tautech]

Did you know Ian is a member here ?
https://www.eevblog.com/forum/profile/?u=4754

Probably a thread about his reference somewhere in the forum.

[kj7e]

I figured he must be    I didn't see anything here regarding V2 with the LM399, but I likely just didnt search hard enough.

[IanJ]

I am here.....

Ian.

[tggzzz]

I notice that the units are burned in for 48 hours. Is there any indication that it is unnecessary to have a longer burn-in period, say 1 week to 1 month?

Background: my limited experience, with a different reference, is that noticable changes occurred over more than 168 hours.

[IanJ]

I notice that the units are burned in for 48 hours. Is there any indication that it is unnecessary to have a longer burn-in period, say 1 week to 1 month?

Background: my limited experience, with a different reference, is that noticable changes occurred over more than 168 hours.

In the first 12hrs I see the output vary on some units (but not all) but then start to settle.

I found that the power cycles, i.e. temperature cycling has more of an initial effect on settling the initial output. On the very first prototype (that Dave saw in his mailbag) the reference used there was reasonable.....until you started the power/temperature cycles......it never powered up twice with the same output. The LM399AH is completely different.

There is also a full battery charge cycle from flat to full on every unit which helps.

But also it's down to the fact I am building & selling these in my spare time and 48hrs fit my production line. Also, given that the user can recalibrate themselves I have never been overly concerned with anything more than 48hrs.
There is a spec for the unit I try to adhere to, anything else is a bonus........but I do read LM399AH's can take a long time to settle (months!) going by what others say..........i'd love to know what other manufacturers do in terms of burn-in times of their LM399AH based units.

I use low tempco resistors around the LM399AH and final output, and making use of some nice LTC2050HV & LTC1250 chopper op-amps.
The DAC itself is the 18-bit DAC9881 from TI........I haven't found anything better.

PS. One thing I have learned........my 3458a is the dogs b******s, whilst my Keysight 34461a doesn't have a great tempco.....I can almost tell the temperature in my workshop using the 34461a and the uV variances.

Ian.

[tggzzz]

But also it's down to the fact I am building & selling these in my spare time and 48hrs fit my production line.

Understood and accepted. If I was doing something like this I think I would buy 10, keep them continuously powered in a test jig, remove 1 at a time when an order arrived and replace it with a new order. Obviously there is an decision about whether to have 10, or 20, or 30 etc

Also, given that the user can recalibrate themselves I have never been overly concerned with anything more than 48hrs.

Always presuming they aren't using this as their primary reference!

PS. One thing I have learned........my 3458a is the dogs b******s, whilst my Keysight 34461a doesn't have a great tempco.....I can almost tell the temperature in my workshop using the 34461a and the uV variances.

I certainly can using my Solartron 7081 and saturated Weston cells But they (+ the 7081) have the advantage of being slightly less noisy than my Trancell.

[TiN]

PS. One thing I have learned........my 3458a is the dogs b******s

I'm not sure I understand this section, could you elaborate?

[Wytnucls]

http://www.urbandictionary.com/define.php?term=Dog%27s%20Bollocks

[TiN]

Alrightie. English ain't my native, have mercy

[kj7e]

Wow, that's all I have to say right now.  Super impressed, thanks Ian!

[IanJ]

Great stuff!........always good to see the unit in somebody else's hands.

Ian.

[kj7e]

Great stuff!........always good to see the unit in somebody else's hands.

Ian.

Running some tests, more stable and lower noise than the LT1021 based reference.  Took me a min to figure out how to move the courser under the digit for the rotary encoder (had to read the manual haha).

[mimmus78]

Ian

Great work!
May I ask you how much you spent for the CE stuff?
Do you apply it only for EMC or also something from the T&M part?

[IanJ]

Ian

Great work!
May I ask you how much you spent for the CE stuff?
Do you apply it only for EMC or also something from the T&M part?

So, I wanted to sell the PDVS2 legally in the UK/EU.......so went looking into CE but found it a minefield. So, I employed the services of Barclay Phelps and was quoted 500UKP but needed a 2nd directive not initially anticipated so total cost 765UKP.
For that I got the technical file including the DoC (in my case EMC, RoHS & EN61326-1-2013 conformity statements).
Then all I had to do was buy the stickers....:-)

Ian.

[kj7e]

Ian,  I did notice the PDVS2 is somewhat sensitive to orientation.  That is, if you tilt it up at an incline say 45 deg to better see the display, the voltage will drop maybe 50uV from 10V.  I suspect warm air around the LM399 is affecting nearby components and at an angle the this slightly disrupts the normal heat distribution pattern. Not a big deal, but I found it interesting.  Have you seen the same?

[Andreas]

Hello

all LM399 are sensitive to orientation (some more and some less).

my K2000 had around 8.4 ppm on tilting

https://www.eevblog.com/forum/metrology/project-pimp-a-keithley-2000/

And I have access to a further K2000 which changes readings even in the range of 20 ppm.
So your 5 ppm are not unusual.

You can improve that (partly) when thermally isolating the LM399.
(from both sides of the PCB -> also the soldering joints).

Of course that may also affect calibration.

with best regards

Andreas

[IanJ]

Ian,  I did notice the PDVS2 is somewhat sensitive to orientation.  That is, if you tilt it up at an incline say 45 deg to better see the display, the voltage will drop maybe 50uV from 10V.  I suspect warm air around the LM399 is affecting nearby components and at an angle the this slightly disrupts the normal heat distribution pattern. Not a big deal, but I found it interesting.  Have you seen the same?

Hi,

Yes, a phenomenon of the LM399, and I have tried to minimize it's effects with holes in the pcb around the LM399 to help thermally isolate it.
I do see the odd unit which does appear to not budge hardly at all in terms of orientation, but unfortunately it's not something that can be specified at order and it's not something I considered measuring and characterizing.
I have two workshop units I use and one is about the same as yours, the other about 20uV.......but all within spec. for the unit.

Not sure if you are running of external DC or batteries, but batteries are the most recommended method of power source. More predictable thermals amongst other factors.

Ian.

[Andreas]

Hello Ian,

which raw voltages do the both references have?
I suspect that the effect is related to the unheated tempco of the LM399.

So LM399s which are closer to 6.875V should be affected less.

with best regards

Andreas

[kj7e]

Ian,  I did notice the PDVS2 is somewhat sensitive to orientation.  That is, if you tilt it up at an incline say 45 deg to better see the display, the voltage will drop maybe 50uV from 10V.  I suspect warm air around the LM399 is affecting nearby components and at an angle the this slightly disrupts the normal heat distribution pattern. Not a big deal, but I found it interesting.  Have you seen the same?

Hi,

Yes, a phenomenon of the LM399, and I have tried to minimize it's effects with holes in the pcb around the LM399 to help thermally isolate it.
I do see the odd unit which does appear to not budge hardly at all in terms of orientation, but unfortunately it's not something that can be specified at order and it's not something I considered measuring and characterizing.
I have two workshop units I use and one is about the same as yours, the other about 20uV.......but all within spec. for the unit.

Not sure if you are running of external DC or batteries, but batteries are the most recommended method of power source. More predictable thermals amongst other factors.

Ian.

I picked up some EBL Li-Ion 9v's as you recommended and found an 18v 1a wall wart on Amazon to use as a charger (guitar distortion pedal power supply), works quite well. 

[IanJ]

I picked up some EBL Li-Ion 9v's as you recommended and found an 18v 1a wall wart on Amazon to use as a charger (guitar distortion pedal power supply), works quite well.

That will will ok.......but just be aware if it is a switch mode power supply then it won't be the best and will inject a little HF noise into the system despite the dual filters on the psu circuit. However, if it's a linear psu then it'll be fine. Saying that, if you are just using it to charge the batteries then no problem.

Ian.

[IanJ]

So LM399s which are closer to 6.875V should be affected less.

Ahhhh, now that I didn't know!

Ian.

[Free_WiFi]

The Ian Johnston's unit is very ,very unique stuff around here (an unique piece of art in he's genre),but if we are talking about the hobbiest purposes then this unit become pretty dead....
I will give my money for it,but only in the case if this unit would be able to do more ,like: µA,mA .
Who knows the future
maybe something like that is coming from the Ian Johnston's horizonts or maybe from something else

[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. 

[Free_WiFi]

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 

[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....
 

[IanJ]

Thinking about this......I think I'll design a separate device, a Precision Digital Current Source.......fully featured from uA to 100mA and include full 4-20mA source/sink functionality.

Ian.

[Vgkid]

You can always implement it as an add on module/unit.

[IanJ]

Hi all,

Couldn't resist testing out the 0 to 2mA source circuit.
I'm using my own PVDS2 to drive the V to I conversion circuit on the breadboard and with the 34461A displaying the output.
10V on PDVS2 converts to 1mA for the purposes of this test.
I also hooked up Dave's uCurrent (1mV/uA) for kicks also and am measuring it's output on my cheap VA38 (questionable cal!).

For a breadboard precision circuit it's quite stable, +/- 0.2uA

Ian.

[ap]

As you work on the new one and as you do an upgrade on the existing one you may wish to have a look at the spec data. Some information might be described a little clearer.
E.g., 0.001% accuracy: this is ususally split into offset and gain and also there is an aging attached to it (not yet established, understand, but...). You will probably not specify 0.001% absolute accuracy (10ppm) of output at any voltage and after say e.g. 10 months. my guess is your voltage standard inaccuracy is maybe already half of it, so not that much left over by the device itself.
Temperature range... I would think, actually, CE had demanded a temp range definition anyhow, so maybe just a miss in transferring this into the manual.
Will help you avoid to not meet expectations you never wanted to meet anyway. And facilitates its use.

[alex-sh]

Hi Ian,

I wonder if you did manage to finish implementing current source into your PDVS2???

Thanks
Alex

[IanJ]

Hi Ian,

I wonder if you did manage to finish implementing current source into your PDVS2???

Thanks
Alex

I did modify one of my PDVS2's to include a 0-2mA current output (keeping the 2v/10v modes), 4 DP's and it works pretty good and can drive a good range of loads. Ever so slightly noisy on that last digit but that's just my prototyping.

No plans to take this into production though, I'd prefer 0-20mA or something like that to make it worth the extra cost...….but it was a fine test.

Pic attached is my one and only prototype........connected up to some cheap arse DMM I just bought and was testing.....

Ian.

[EEVblog]

Pic attached is my one and only prototype........connected up to some cheap arse DMM I just bought and was testing.....

That meter looks dodgy-as!

[EEVblog]

No plans to take this into production though, I'd prefer 0-20mA or something like that to make it worth the extra cost...….but it was a fine test.

I think it would at least need to cover the two shunt ranges, mA and uA.
So maybe 0-200uA and 0-20mA to make it really worthwhile?

[alex-sh]

Where did you get that multimeter? I bet eBay is selling thousands of those

Pic attached is my one and only prototype........connected up to some cheap arse DMM I just bought and was testing.....

Ian.

[alex-sh]

No plans to take this into production though, I'd prefer 0-20mA or something like that to make it worth the extra cost...….but it was a fine test.

I think it would at least need to cover the two shunt ranges, mA and uA.
So maybe 0-200uA and 0-20mA to make it really worthwhile?

I think Dave has got a point here. Personally, I'd be more interested in 0-200uA, but this would have to have to upper scale too

[IanJ]

Where did you get that multimeter?

Found it in a dumpster (as mr. Jones would say).......ahem!

Ian.

[hwj-d]

Pic attached is my one and only prototype........connected up to some cheap arse DMM I just bought and was testing.....

That meter looks dodgy-as!

Hmm, with my poor aussi-inglish, for the very first moment i had read "doggy-ass" ... 

[alex-sh]

Ian,

I just wonder if you do not see a market for such devices or what's the reason you put development on hold?

Thanks
Alex

[niner_007]

Hello

all LM399 are sensitive to orientation (some more and some less).

Hi, would it make sense to use silastic to keep the LM399 plastic enclosure from moving (and on the PCB)?

[2N3055]

Hello

all LM399 are sensitive to orientation (some more and some less).

Hi, would it make sense to use silastic to keep the LM399 plastic enclosure from moving (and on the PCB)?

Andreas didn't mean that LM399 is sensitive to vibration or pin or case stress.
In testing it was shown that if you take whole device that has LM399 inside (like multi-meter or reference) and put on one side, on the other side or upside down, in each stationary position it will give a slightly different output voltage, on PPM level order of magnitude of difference.
It probably has to do with slight difference in thermal flow of LM399 in different orientation......
Metallic case of LM399 is not sensitive to device pin stress...