NEW PDVS2mini DC Voltage Reference from Ian Johnston - Reviewed.

[GingGangGooly]

Any idea of cost for a new 1.6 device?
(for budget purposes) 👍

[Ecogeek]

Hi Johannes, thanks for the update and all the best. I have a question?  For the new version of PDVS2mini, has the LM399 been upgraded to the ADR1399? Or is this an option when ordering?   
It would seem the ADR1399 has several advantages over the older model including lower noise, be it at the cost of a higher zener current and lower battery run time.
regards from Australia

[wrytech]

To address the points brought up:

• Hope the first batch can go on sale in around 2 weeks; all things are bureaucratic things are set up now and the things at hand are more logistical now. Started calibrating the first half of the first batch today, the second half is still burning in until end of next week, gathering packaging, etc. ... People registered on the newsletter on the website will be the first ones to be notified, with further announcements here, etc. then some time later
• Budget-wise I would allocate 359€ net plus shipping (which I will try to keep at what I pay plus packaging, etc.)
• At this point no upgrades / changes to the analogue part of the design have been done. First step is to get v1.6 where Ians units were as well. Also have partial stock left for around 150 units which I will use up before making relevant changes to the design. Would also like to be able to quantify the advantages in some way when changing over to the ADR1399 for example as it will come with an increase in price as well which further complicates things. So, this is something more for the mid to long term...

Firmware is fully updated as well and now also supports the internal temperature and new calibration point via serial. A big thanks to Ian for kindly updating WinGPIB to be compatible with the v1.6 units as well so quickly!

Thanks
Johannes

[wrytech]

And the shop is live: https://www.wrytech.eu/

Units went on sale on Friday, as was announced via the newsletter, but there is some stock left so no worries there (and I am already planning the order for the next batch haha)

All orders were shipped today, so waiting for any feedback to come in now. Thanks to everybody who has already ordered one, signed up for the newsletter or reached out to me in general! I am glad to see the interest and the trust shown - it means a lot to me.

Best,
Johannes

[glitchcatcher]

I could never get my hands on Ians original, but this must be a totally awesome continuation. I'm glad this project is in good hands again

I was wondering a bit about the newly added temperature sensor, but after looking at the Certificate of Calibration which comes with the unit, the Internal Temperature during Calibration is stated there as well in addition to the ambient temperature, so it all makes sense.

Another issue is that I cannot find any mentions about using non-rechargable 9V batteries. I found some article saying it's not recommended but there was no source or reason given (probably safety).
I don't have rechargable ones lying around, so I'm using Varta 9V Lithium with 1200mAh. Will last only about 24 hours though, so not ideal, especially considering the price of those.
Obviously I won't connect external power, and I've disabled charging in the options as well.

Then I had the idea to burn this in for a long long time (potentially years) which brings up a concern: Is there a MTBF or something specified for the display? Could it possibly be switched off per software? Or is this a non-issue?

[ivo]

Another issue is that I cannot find any mentions about using non-rechargable 9V batteries. I found some article saying it's not recommended but there was no source or reason given (probably safety).
I don't have rechargable ones lying around, so I'm using Varta 9V Lithium with 1200mAh. Will last only about 24 hours though, so not ideal, especially considering the price of those.
Obviously I won't connect external power, and I've disabled charging in the options as well.

A lot of the time this is simply because, being human, we'll forget that we left a 9V alkaline cell in our precious device, leave it for 6 months, then by murphy's law come back and see that it has been ruined by leaking in that time. It's also possible that 9V alkalines might not stand up very well to the inrush current of the heating reference when the device turns on, given it's effectively 12 tiny battery cells in series. Or just at the rate they'll get drained, you'll be making a lot of environmental waste...

[Kleinstein]

The display is a simple passive LCD. There should be not issue with keeping it running for a long time. So no need to turn it off.

[krebacz]

I have received mine middle last week and so far I am very happy with it.
I am a beggining voltnut - so a Keithley DMM6500 for now (6.5 digits).
The PDVS 2 Mini 1.6 has firmware 1.11 and, after a brief warm up (28+ deg C internal, about 5 mins from ambient 23-24 now) is within +- 1 LSD - 10uV on 10V range. On 1V and 100mV ranges it is similar, sometimes up to 20uV.
My Keithley has the last (and first - factory) cal date of 05.2023.

Everything seems in order and the accuracy can flow to my handheld meters.

Thanks Johannes for the quick delivery and an amazing continuation to Ian's work!

[wrytech]

Thanks a lot for the feedback provided and the units shown here - great to see them put to use!

Non rechargeable batteries can be used, of course, as long as nothing is connected to the input jack to prevent any chance of the PDVS 2 Mini trying to charge them. Reasons against using non rechargeable ones are mostly related to convienience and cost, as it gets quite tedious and ultimately expensive to constantly exchange the batteries..
Inrush current should not really be a problem, as there is a small resistor in series with the heater limiting it during startup.

Regarding the LCD, I dont really have any concerns regarding longevity, as so far I am not aware of any problems being reported for Ian's units that are out there. It's socketed anyway, so it can be fairly easily exchanged if required. However, I do not recommend removing it for any other reason, as it's somewhat fiddly to get it to sit right with all the pins and quite hard to pull out without breaking the display, as I found out quite quickly 

Thanks,
Johannes

[IanJ]

The display is not an OLED and so does not degrade over time in the same way. The LCDs are robust, feel free to leave them powered up for many years. In addition, I never had faulty ones ever from memory.

There is a trick I used to remove the LCDs, use the handle of your side cutters (plastic) under the LCD and wedge it up a corner at a time……..enough at one side till it’s loose enough to pull it off by hand.

Ian

[J-R]

I see this latest batch has sold out.  Any news on future production runs or a more regular/reliable supply?

[wrytech]

I did start production of the next batch over the weekend. Had the PCBs here for a longer time, but had some units left in stock, that then all sold out in a couple of days...

With the burn in required the units should become available towards the end of November. Will announce it here then and via the newsletter.

Best,
Johannes

[Cyclotron]

I did start production of the next batch over the weekend. Had the PCBs here for a longer time, but had some units left in stock, that then all sold out in a couple of days...

With the burn in required the units should become available towards the end of November. Will announce it here then and via the newsletter.

Best,
Johannes

Did I miss the announcement? Per the update above, I thought units would be available for purchase at the end of November.
Thanks

[J-R]

I don't think you missed any announcements.  He's probably still working on the latest batch.

[Cyclotron]

I don't think you missed any announcements.  He's probably still working on the latest batch.

Thanks, I travel a lot and often don't have a chance to check back on the personal stuff I'm working on.
I wanted to get one of these when the next batch was out.  I think I'm signed up for the emails.

[J-R]

My opinion is that there is not quite as much pent-up demand for these now.  The last two took weeks to finally sell.  Hopefully he can keep them in stock going forward because it's very annoying to recommend a product that nobody can actually buy!  I'm sure making them in batches is more cost-effective, though.

[IanJ]

My opinion is that there is not quite as much pent-up demand for these now.

I don’t think so, no change from my days…….probably more demand now.

Ian

[ITArchitect]

I waited more than a year to get mine and it was worth the wait.  Any bench can benefit!  I use it every day and would love a backup!  Please make more!   

[J-R]

Is this a teaser? https://www.wrytech.eu/cdn/shop/files/DSC03595.jpg

[skander36]

Is this a teaser? https://www.wrytech.eu/cdn/shop/files/DSC03595.jpg

   I want this!

[Martinn]

With the burn in required the units should become available towards the end of November. Will announce it here then and via the newsletter.

Now there are two versions, one with LM399 and one with ADR1399.

Which one should I buy? The ADR1399 is fairly new and I am not sure if there is sufficient experience regarding long time stability.

Thanks! Martin

[Cyclotron]

Now there are two versions, one with LM399 and one with ADR1399.

Which one should I buy? The ADR1399 is fairly new and I am not sure if there is sufficient experience regarding long time stability.

Thanks! Martin

I went ahead and bought the ADR1399 model. If there's issues long term I can get an LM399 version then.  I guess I'll just plug it up and turn it on and let it stay that way on the bench to age. I'll start checking its accuracy each year after my meters are calibrated.

[Kean]

Hey wrytech,

On your page for the IUSL - Isolated USB Serial Link for PDVS 2 Mini, it mentions:

Required software version 1.2 available for download in the resources tab

I don't seen any software under the resources tab.
Is v1.2 just an updated Windows app, or does it involve newer firmware and if so can end users update firmware on their pre-v1.6 hardware?

I have a similar isolated USB serial from DuPPa.net.  Pin ordering is different, but I can deal with that.

Thanks!

[telectric]

Missed the latest go around. Is there an ETA for the next batch?
Also, for shipments outside the EU (USA) is the VAT subtracted from the price?

Looking forward to having one.

Thanks, WT

[wrytech]

Finally found some time to catch up here as well...

New batch went on sale on Saturday, with an ADR1399 version now available as well. Apart from the changed reference, nicer gold-plated banana jacks are included as a little extra bonus. Since quite a lot of people asked about the ADR, I decided to go ahead and make this variant as well. The changes in circuitry are small anyway.
Currently, the ADR ones are out of stock, but there are 2 more coming that started the burn-in process later. I hope to get them calibrated over the coming weekend and will put them online then. Parts for more ADR1399 are already ordered, with the usual lead time mostly due to the burn in...
The goal is definitely to have a stable supply going forward; I just didn’t really know how the reaction to the ADR ones would be.

LM399 ones are available - as usual everything that is listed as in stock in the shop will be shipped immediately.

Is this a teaser? https://www.wrytech.eu/cdn/shop/files/DSC03595.jpg

That was way faster than I would have imagined and yes this is a teaser. Some work still needs to be done on the software and unit characterization, but I’d say most things of interest are visible in the picture...

On your page for the IUSL - Isolated USB Serial Link for PDVS 2 Mini, it mentions:

Required software version 1.2 available for download in the resources tab

I don't seen any software under the resources tab.
Is v1.2 just an updated Windows app, or does it involve newer firmware and if so can end users update firmware on their pre-v1.6 hardware?

I have a similar isolated USB serial from DuPPa.net.  Pin ordering is different, but I can deal with that.

The software hasn’t been uploaded yet, as instructions for updating and a changelog still need to be prepared—I hope to get it done over the coming weekend. New PDVS 2 Minis ship with the updated firmware and no individual IUSL have reached their buyers yet, so not that much of a problem yet...
The changes mostly focus on improving serial connection functions and making them more flexible. Currently, the baud rate is fixed at 250,000, which can cause issues since it's somewhat uncommon, and people have reported problems with it. Version 1.2 will be fully backwards compatible and run on pre v1.6 PDVS 2 Minis as well - no worries there.
The DuPPa adapters are good and work with the 250,000 baud rate, but dealing with the non-matching pinout became annoying, so I went ahead and made the IUSL.

Missed the latest go around. Is there an ETA for the next batch?
Also, for shipments outside the EU (USA) is the VAT subtracted from the price?

See above, LM399 ones are available, 2 ADR ones are coming on a shorter notice and then more some time early next year (hopefully).
VAT is excluded for shipments outside the EU, with import taxes and other fees to be handled by the buyer as usual.


Thank you for all the comments, questions, and feedback here! With the usual pre-Christmas rush at my day job, there's quite a bit of juggling to do, so please bear with me if things take longer than expected or if communication is a bit slow on my end.

Johannes