NEW PDVS2mini DC Voltage Reference from Ian Johnston - Reviewed.

[TheDefpom]

Hi All,
I thought I would pop this here, I just published a review of a new piece of equipment from Ian Johnston, the PDVS2mini, which is a 0-10V DC voltage reference.

No doubt you will spot things I am doing wrong, I'm not a metrology guy after all, but hopefully the video demonstrates the capabilities of the unit.

[IanJ]

Hi all,

Working on a couple of software bugs at the moment, mostly down to the math.h library which isn't great on these small AVR's (it can't add or subtract properly!). So, having to write (C++) around the issue which is a pain.
Scott's low end non-linearity problem I don't experience on my own PDSV2mini's here.......so some detective work is required.

Prototyping Happy days!

Ian.

[Svgeesus]

So, the Integral Non-Linearity is higher than the PSVS2, but because resolution is also higher it is compensated for in software?

[branadic]

Scott, your meter also has INL which is not zero. You could use your F343 and make differential measurements to get more into that.

-branadic-

[IanJ]

So, the Integral Non-Linearity is higher than the PSVS2, but because resolution is also higher it is compensated for in software?

PDVS2 (18-bit DAC9881) INL = +/-2 LSB typical, +/- 3 LSB max.
PDVS2mini (20-bit MAX5719A) INL = +/- 1 LSB typical, +/- 20 LSB max.

The +/- 20 LSB is scary (when volt-nutting) so there is 11 y=mx+c calib setpoints between 0 and 10Vdc output (1Vdc apart).......to compensate/help minimize any deviation.

An alternative solution would have been to add in an ADC (low INL) and monitor the DAC output and compensate accordingly, but that just pushes the BOM/complexity up..........

Ian.

[MiDi]

Scott's low end non-linearity problem I don't experience on my own PDSV2mini's here.......so some detective work is required.

Assuming the PDSV2mini does no range switch, this simply shows the DNL.
The DS states a DNL of +-1LSB@25°C -> +-10uV@10V FS (This means that this DAC even may not be monotonic).
And it is unlikely that this is only in the low end, the Fluke meter has not enough resolution to show this accurate in 1V/10V range - as Scott already stated.

Ian, are you sure that yours have better DNL?

[IanJ]

I have 2 others sitting here from the same batch and an older one......and on my 3458A no real linearity problems (exception: see below) including at the low end.

However, I had found an issue with the firmware which generated a 1 or 2bit random inaccuracy. It's a well known math.h library problem (it can't subtract/divide properly and shows up as a rounding error!). It's fixed now and makes a nice difference.

This weekend I'll check Scott's video properly and look into the low end issue......but I am beginning to think it's just DNL as we are right down at 1bit step changes......which are magnified in Scott's mV mode on his DMM. My testing has been done on the same 3458A mode across the full range and shows no difference between high or low.

Maybe I will try adding a range selection like I did on the PDVS2, an extremely low RDSon Fet and a low tempco resistor or two. This DAC doesnt have the same Vref range unfortunately, but there are other ways. Hmmmm!

Ian.

[TheDefpom]

Ian did a firmware update to 1.01 which I applied to my prototype unit (Ian corrected a problem the math library, as mentioned above), the unit steps by 10uV without missing a beat now, I barely even noticed the original issue anyway but now it is fixed.

[IanJ]

Ian did a firmware update to 1.01 which I applied to my prototype unit (Ian corrected a problem the math library, as mentioned above), the unit steps by 10uV without missing a beat now, I barely even noticed the original issue anyway but now it is fixed.

Yep, V1.01 is definitely a winner, and subject to some on-going testing being completed I should be going into production in the coming couple weeks.

Maths error:-
On 8-bit Atmel AVR controllers the float type is 32-bits which makes the limit 6 or 7 digits......close to the bone and causes rounding errors when working at 5dp's.
So, rather than rely on the maths library doing any rounding I have taken control of it just before converting and sending to the DAC......thus forcing it the way I want it.

Anyone interested in purchasing please use the NOTIFY ME link and as soon as I have stock you'll get an email.
https://www.ianjohnston.com/index.php/onlineshop/handheld-precision-digital-voltage-source-2-mini-detail

Ian.

[niner_007]

Can't wait to get one

You should consider an STM32, not only will it use less power than the AVR, but better software and libraries too

[IanJ]

You should consider an STM32, not only will it use less power than the AVR, but better software and libraries too

Something for the future maybe........but what puts me off slightly is the lack of EEprom, albeit they do have EEprom emulation in flash via paged memory or something like that........well, thats as much as I know about STM32 anyways.

Ian.

[niner_007]

You should consider an STM32, not only will it use less power than the AVR, but better software and libraries too

Something for the future maybe........but what puts me off slightly is the lack of EEprom, albeit they do have EEprom emulation in flash via paged memory or something like that........well, thats as much as I know about STM32 anyways.

Ian.

STM32 have both eeprom (STM32L010F4 for example) and non volatile flash, depending on the model, which will allow you to store calibration constants and so on, but why do you need eeprom specifically? the API for reading and writing to the flash is quite fine, maybe I'm missing something

[TiN]

I don't like STM, their marketing here in TW failed hard when I tried to get some support to consider using STM32 on a project. 

Now let's get back on topic. I got this little cute PDVS2mini in thermal box, running for life first quick and dirty tempco test.



I'm sure somebody will dig a photo with $70K vs $300 DC source .



Design assembly is nice and tidy, with all critical stuff well cared. Graphical LCD is not backlit, just COG panel. It has decent contrast and main output voltage have nice large digits. The menu system is little unusual but not hard to figure out without any RTFM. There is a help string on the bottom strings to show keypad actions.



Access to battery requires removal of 4 screws, and also provide a way to see some internal construction.
There is no separate battery compartment or protection over electronic parts, due to low-cost targeting reason, which is understandable.
PDVS2mini designed to use two 9V batteries in series, with integrated charger. Unit needs to be powered on to allow charging from external DC jack.

I'm working on detailed review/testing, but it will take some time, so here are just some initial dirty results using my secondary equipment (K2002 and Arroyo TECpak controlled box).

PDVS2mini is powered by batteries, placed in DIY chamber. Raspberry Pi controls Keithley 2002 as a digitizer, and TECpak 585 for precision temperature control. 40W noname TEC used as cooler/heater, with water-cooling loop dissipating heat into room elsewhere. The sensor in the box is Honeywell HEL-705-1 100 Ohm platinum RTD. This thermal box setup may not look like much, but its able to maintain any programmed temperature from -5 °C to +65 °C with better than 0.008 °C stability over hours.



Now to the first test results. The first graph is a plot of +10V output from PDVS, with temperature change from +15.00 °C to +55 °C in a slow and controlled manner. There is soaking time at +35°C for 2 hours, and also at peak max temperature, to get an idea of settling and hysteresis behavior. The horizontal axis is time duration, vertical axis is deviation from initial point at +15 °C, which happened to be +9.999994 VDC +/-2ppm.

For illustrative purposes, chart have additional plots of -0.1 ppm/K and -0.2 ppm/K thresholds based on temperature change (using box method) and TEC current readout from Arroyo TECpak 585. Ramp up time for temperature is +0.08333 °C per minute. Measured deviation is -4.0 ppm for +15.0°C to +35°C ramp, and another -5.3 ppm for +35°C to +55°C ramp. Following the TC Box method we can estimate temperature stability at max -0.23 ppm/K which is impressive for $300 USD DAC box!



Now same data, but in voltage/temperature scale representation. Hysteresis on fixed temperature points is around ~2ppm but that will need additional verification with proper setup Unit may need additional time, longer than 30min to get temperature soaked to reach equilibrium. This particular temperature chamber does not use forced airflow, and from datalog looks like it need ~30 minutes to equalize temperature change.



Stay tuned for more

One part I'm not very happy about is banana-only output connectors. Once initial testing and calibration verification test is done, these will be for sure changed to some proper low-thermal EMF hardware  .

If somebody wants particular test setup/conditions - feel free to give feedback.

[TiN]

And battery died after 12.5 hours. 

[chickenHeadKnob]

When you consider that most people would want to keep this device a long time and that the value of the reference to the particular end user increases over time it would be a shame to lose everything to battery leakage. I would extend the battery connector to an external connector as the very first  modification and permanently run from external power.

[2N3055]

When you consider that most people would want to keep this device a long time and that the value of the reference to the particular end user increases over time it would be a shame to lose everything to battery leakage. I would extend the battery connector to an external connector as the very first  modification and permanently run from external power.

If you keep it normal side up (screen up) it will leak to the bottom of the box, not electronics. Also, it uses rechargeable Li-ion PP3 9V batteries that are not leak prone...

[chickenHeadKnob]

If you keep it normal side up (screen up) it will leak to the bottom of the box, not electronics. Also, it uses rechargeable Li-ion PP3 9V batteries that are not leak prone...

That is good to know, I would still want to keep it powered continuously with a linear supply to age the lm399 for the first three years. There-after I suppose you could switch to intermittent power-ups. 

[TiN]

This device is not designed to be a permanent DC voltage standard, but a portable programmable DC source/DAC. LM399 is not really worthy of proper DC standard anyway due to noise/stability and tempco.
And it can run long time with external charger/PSU connected to the Charge port. PDVS2mini is much cheaper than another 5.5-digit source alternatives, even tho output is limited to only one 0V - 10V range.
Better DAC option are some 30kg+ anchors like Fluke 5440 and alike, for which you need to be in right country/right spot/with cash in hand and will to repair/troubleshoot boards and modules when things go sour.

Handy option for beginner volt-nuts. And if you think ~$300 USD is too much, well, MAXIM's eval board with used DAC, without LCD, case, charger or LM399 already cost $190 . Another popular "volt-nut" DAC with AD5791 with LTZ ref is even more, close to $500 USD.

Don't get me wrong, I'm not implying somebody should calibrate 3458A with PDVS2mini  ,
It's more of educational precision DC source kit, that is fun to have around for some simple tests, without expensive demands for accuracy. And for this role it looks like priced adequate, and 24/7/365 operation is not a requirement.

[TheDefpom]

The unit is pretty damn good for the money, yes it has a dc input jack for charging the batteries, it can run from that in itself, however due to introducing noise via that input, and the extra heat generated during charging Ian recommends that it not be used that way to avoid it affecting the output accuracy.

[IanJ]

Apart from the possible introduction of noise depending on your DC power source......and by example running at 20Vdc at the power jack sees the output vary by about 10uV (1bit !) eventually due to the extra internal heat being generated.
On disconnecting the DC input it takes approx. 30mins for the unit to return to it's normalized output.
I've tried to minimize this heat induced drift by mounting the LM399AH externally, it's under the LCD in it's own little 3D printed conductive PLA thermal cover.

Running off DC permanently then has it's issues per above, but is entitely safe. The MAX1873 battery management IC recognizes an external supply and once the battery is detected as fully charged it will cease charging completely and the DC supply is used to feed the rest of the circuit. The batteries remain in isolation effectively and are not in any way trickle charged.

I haven't had a Lithium-Ion battery leak yet and I have about 40 of them which have been charged, drained and left sitting for months on end in and out of PDVS's.

PS. This unit was never directly designed as a "reference"......it was designed as an adjustable precision voltage source, but with some capabaility of a reference.
Quote from my website "With a user adjustable range from a true 0V to 10Vdc and an accuracy/stability down in the uV’s it has a multitude of uses as a calibrator, reference & precision voltage source."

But TiN is right.........not a great idea to calibrate a 3458A with it........

I'll be in production soon with it.

Ian.

[MegaVolt]

Are you planning to add a remote control?

[IanJ]

Are you planning to add a remote control?

It has a serial header and you can control it remotely from a PC already much the same as the PDVS2 with an appropriate adaptor......however, I will just be supplying the Ascii protocol used and not a Windows app (well, I might supply an EXE unsupported).

Ian.

[MegaVolt]

It has a serial header and you can control it remotely from a PC already much the same as the PDVS2 with an appropriate adaptor......however, I will just be supplying the Ascii protocol used and not a Windows app (well, I might supply an EXE unsupported).

Thank . I did not notice the serial connector.

[IanJ]

Hi all,

I have just made the first batch of units available in my online shop. Here:-

https://www.ianjohnston.com/index.php/onlineshop/handheld-precision-digital-voltage-source-2-mini-detail

Available worldwide with shipping via UPS courier.

Thanks,

Ian.

[oz2cpu]

i am not sorry for kicking this topic back alive :-)
wow amazing product you made there Jan, all looks super professional

I really like to see some closeups of the mecanical implementation of the LM399
you say it is under the display ?
and inside 3D printed isolation case ?
the display looks like it can be taken out, so this detail could be revealed,

[Grandchuck]

It is an amazing product.  Mine does not seem to be drifting at all.  The reason I must use the word "seem" is due to an interim calibration/adjustment for my 3458A.  I wasn't careful enough and should have made more measurements and records.  I confess to being a bit of a sloppy volt nut

[IanJ]

i am not sorry for kicking this topic back alive :-)
wow amazing product you made there Jan, all looks super professional

I really like to see some closeups of the mecanical implementation of the LM399
you say it is under the display ?
and inside 3D printed isolation case ?
the display looks like it can be taken out, so this detail could be revealed,

Hi,

Here's the LM399 cover.........3D printed in conductive PLA, and grounded to the pcb GND via it's mounting screw, a pad and a ring around the LM399.

[IanJ]

Spec of the conductive PLA from the datasheet:-

How Conductive Is It?
● Volume resistivity of molded resin (not 3D Printed): 15 ohm-cm
● Volume resistivity of 3D printed parts along layers (x/y): 30 ohm-cm
● Volume resistivity of 3D printed parts against layers (z): 115 ohm-cm
● Resistance of a 10cm length of 1.75mm filament: 2-3kohm
● Resistance of a 10cm length of 2.85mm filament: 800-1200ohm

Ian.

[Anders Petersson]

Are there any long-term stability measurements? For example calibration over several years.

[IanJ]

Are there any long-term stability measurements? For example calibration over several years.

The closest I have is a customer who bought one in Oct. 2019, and then damaged it in Oct. 21 and it was sent to me for repair. A protection diode was replaced and then a full re-cal.
Unfortunately, back in 2019 I didn't produce as full a cal cert as I do now, however, you can see the BIT COUNT changes I had made on the re-cal which will give you some idea.

As follows:-

[Anders Petersson]

The closest I have is a customer who bought one in Oct. 2019, and then damaged it in Oct. 21 and it was sent to me for repair. A protection diode was replaced and then a full re-cal.
Unfortunately, back in 2019 I didn't produce as full a cal cert as I do now, however, you can see the BIT COUNT changes I had made on the re-cal which will give you some idea.

Thanks. Comparing a few of the data points, I only see 1-2 counts correction.
If you place a few units in different storage conditions and record their calibration every few months, that could answer the "tba" placeholder for drift in your specifications to increase the (already high) value of your product.

Nitpicking: The certificate specifies 11 digits for voltage output which seems optimistic. Also, including some calibration/accuracy estimation of your 3458A would be helpful.

[guenthert]

The closest I have is a customer who bought one in Oct. 2019, and then damaged it in Oct. 21 and it was sent to me for repair. A protection diode was replaced and then a full re-cal.
Unfortunately, back in 2019 I didn't produce as full a cal cert as I do now, however, you can see the BIT COUNT changes I had made on the re-cal which will give you some idea.

Thanks. Comparing a few of the data points, I only see 1-2 counts correction.
If you place a few units in different storage conditions and record their calibration every few months, that could answer the "tba" placeholder for drift in your specifications to increase the (already high) value of your product.

Nitpicking: The certificate specifies 11 digits for voltage output which seems optimistic. Also, including some calibration/accuracy estimation of your 3458A would be helpful.

First of all, those numbers are most impressive. 

     There's nothing wrong per se with 11 or more digits, but w/o estimate of the measurement error, they are a bit questionable.  Sure, we can look up the uncertainty Agilent promises to better with the 3458A, but that tells us little about your unit nor how much additional error is introduced when measuring the calibrator (I'm sure there are codified / documented best practices, but an ad-hoc approach might be to use an example unit, measure it's voltage a number of times over multiple days, inverting polarity and calculating the standard deviation from that -- that at least gives a hint about the quality / reproduce-ability of the measurement procedure).

[IanJ]

Thanks guys, some good points there.

My automated procedure just logs directly what the 3458A output gave at the time with an NPLC of 100.
Are those numbers reproducable?......no, certainly not at 11 digits, but i figured if thats the numbers the 3458A sees then thats what i record. To be honest, i didnt think twice about it.

I'll look into pulling those digits back on the cal certs on future ones, or maybe adding a statement to the certs.

Thanks,

Ian.

[TiN]

Or just remove everything after 7th digit and call it a day.
I wonder if Ian considering to use new 1399 reference in PDVS "3" mini version? 

[IanJ]

I wonder if Ian considering to use new 1399 reference in PDVS "3" mini version? 

Hmmmmmm!

Ian.

[TheDefpom]

Thanks guys, some good points there.

My automated procedure just logs directly what the 3458A output gave at the time with an NPLC of 100.
Are those numbers reproducable?......no, certainly not at 11 digits, but i figured if thats the numbers the 3458A sees then thats what i record. To be honest, i didnt think twice about it.

I'll look into pulling those digits back on the cal certs on future ones, or maybe adding a statement to the certs.

Thanks,

Ian.

I would be inclined to leave all the digits there, might even help identify minor drifts with the 3458A... there are "only" 5 decimal places on the PDVS2mini, with the last one known to have a little rounding due to DAC conversion, I really wouldn't worry about it, people will only be looking up to the 5th/6th decimal place I expect, the rest is for your own records.

[IanJ]

I would be inclined to leave all the digits there, might even help identify minor drifts with the 3458A... there are "only" 5 decimal places on the PDVS2mini, with the last one known to have a little rounding due to DAC conversion, I really wouldn't worry about it, people will only be looking up to the 5th/6th decimal place I expect, the rest is for your own records.

NIST would have trouble with 11 digits......heading into superconducting JAWS territory.
9dp's on my certs are not stable, not reproduceable so kinda pointless being there.
If i run the autocal again the numbers wouldnt be the same.
The PDVS2mini isnt that stable......so TiN is right, 7 digits will do.
It's a Precision Voltage Source, not some high grade piece if metrology gear.

Gotta be totally honest/clear when selling.........

Ian.

Update, it's fixed (example):-

Code: [Select]

volts10.Text = Format(Val(txtr1aBIG.Text), "#00.0000000")

[J-R]

Has anyone experimented using the PDVS2mini and a resistor voltage divider to generate much smaller voltages or with an external circuit to make a precision current source?

[skander36]

Hi @IanJ !
Two quick questions.
1. Why aren't you used AD 5791 for DAC?
2. The schematics can be obtained, in order to make an output amplifier that can be driven by PDVS2mini?

Thank you!
 

[IanJ]

Hi @IanJ !
Two quick questions.
1. Why aren't you used AD 5791 for DAC?
2. The schematics can be obtained, in order to make an output amplifier that can be driven by PDVS2mini?

Thank you!

The AD5791 is very expensive, and requires a more complicated power supply circuit. Easy to do but affects the BOM.
The schematic diagram is not available I am afraid.

Ian.

[skander36]

Indeed, is more expensive and now is "unobtanium".
There is a project with AD5791 as a calibrator but max 20 uV step.
I'll see how I will extract output of the calibrator for interfacing an external amplifier.
Thank you!

[deepfryed]

The AD5791 is very expensive, and requires a more complicated power supply circuit. Easy to do but affects the BOM.
The schematic diagram is not available I am afraid.

Ian.

On that topic, another question is why not use a discrete PWM DAC ? It looks like some of the old HP voltage sources use that design to get 6.5 digit accuracy. I'm only a hobby tinkerer, so if that's a silly question feel free to say so.

I'm thinking of making a hobby grade programmable source as learning exercise with a decent 10v reference like LT1021C, with a discrete PWM DAC driven by a STM32, analog switch like ADG1611 and a low pass filter. 

[deepfryed]

Heh, DAC schematic from 3245A. This might explain it

Still going to tinker with a simpler version and see how I go

[skander36]

About a month Ian has posted on Youtube a repair video of 3246A  - https://www.youtube.com/watch?app=desktop&v=0EPc8ttbU3Q

[p.larner]

is the schematic+fw available for this to homebrew one?

[skander36]

is the schematic+fw available for this to homebrew one?

https://www.eevblog.com/forum/metrology/new-pdvs2mini-dc-voltage-reference-from-ian-johnston-reviewed/msg4287775/#msg4287775

[J-R]

Just saw this on Ian's PDVS2mini page (https://www.ianjohnston.com/index.php/onlineshop/handheld-precision-digital-voltage-source-2-mini-detail):

"I have decided for logistical and health reasons to stop making PDVS2mini’s permanently.
If you’d like to purchase the rights to the design, all design files and my remaining stock of parts then please contact me.
The PDVS2mini is a very successful and well respected product, it deserves to live on.
Business enquiries only"

[deepfryed]

Oh noes, I've always wanted to get one and missed out on the last round. Too bad, hope you're ok Ian. Take care.

[IanJ]

Yeah I am fine.....health wise nothing drastic just can't hover over the workbench for days-on-end anymore.
I've had a few enquiries thus far and options to look at.......hopefully one of them will work out and the PDVS2mini will continue.

Ian.

[J-R]

Whew, glad to hear your health issue is nothing drastic!

Maybe you could find someone to do the harder parts like populating the PCB. I also think it would still sell at a higher price point, so you could take your time and make fewer?

[Paul_txl]

I've been looking at buying one for a couple of years but I thought you had stopped selling them post covid. I should have used the "email when available" link, my bad. Glad its nothing too serious thats stopped you and hope you enjoy your other interests.

[glitchcatcher]

Woah, all the best Mr. Johnston!

Absolute bummer though, this product is amazing and deserves to be continued! And I was waiting for the new production..

Wish I could help with this, but I'm afraid I lack the experience. Hopefully a new partner can be found soon!

[J-R]

Just saw this:
"The design rights to the PDVS2mini has been SOLD.
Forwarding information for the new manufacturer will be published soon."

[IanJ]

Just saw this:
"The design rights to the PDVS2mini has been SOLD.
Forwarding information for the new manufacturer will be published soon."

Nearly 5 years of home production of the PDVS2mini and 40yrs in the oil industry (mostly electronics related) it's time to retire, part health issues and part "it's time".
The demand for the PDVS2mini has never been higher and I think it will be in great hands, so please give them some time to get their ducks in a row, keep your eye on my website for updates.

For me, I am still doing a couple days a week in oil just for a wee while so the folks taking over my work can make good.......so lets, for the moment, call it semi-retirement.
Meanwhile I am forging ahead having fun with my YouTube channel and test instrument repairs.......so if you have any faulty gear you don't need then please contact me.

Ian.

[donlisms]

Ian, this enhanced picture of what's going on with you is encouraging for those of us who tend to assume the worst.  Thanks for the update. All the best!

[p.larner]

why not release this as an open source project?.

[2N3055]

why not release this as an open source project?.

And why would he?

It is a low cost calibrator. Apart from Ian making a nice and elegant design, for users of device 99% of utility of buying it was fact that Ian kept calibrated KS3458 that he calibrated devices with. And he did a top notch job, too.
You were buying calibration, mostly, not device per se.
Without proper calibration it's not very useful...
Without proper calibration it is just a source of stable voltage.

And also, people that do the hard work should get paid for it.

[TheDefpom]

Ian deserved to earn some money by selling his design to someone that was willing to continue the work and ensure that people could still buy the units, and as mentioned, building the thing is only half of it, a decent calibration of the PDVS2mini is the critical bit there.

[Kean]

why not release this as an open source project?.

If he was shutting his business down completely, then that would be ideal.  It benefits the community and allows existing owners to maintain their units.
But as 2N3055 explains, a large part of the value of such a device is in the calibration which your average DIY builder would not have access to.

For as long as it is a viable product, it makes much more sense to sell the business/IP as a going concern and have someone continue the manufacture and calibration.  While the market is somewhat limited, there was clearly demand as Ian would quickly sell out of each production batch.  It took me a few in-stock notifications before I had an opportunity to grab one for myself.  His pricing was very fair, and I don't think anyone reputable could provide them significantly cheaper.

[skander36]

why not release this as an open source project?.

There are other projects as open sources.
One of them is here - https://www.elektormagazine.de/labs/voltage-current-calibrator-0-to-10v-and-0-to-40ma-0001
with atempts to replicate here : - https://www.eevblog.com/forum/testgear/elektor-voltage-current-calibrator-project/
But as you can see and guys here explain before me, the main issue is the calibration of such device, even the methodology for aquiring repetable results is not easy.
 

[J-R]

Ian starts talking a bit about his now sold PDVS2mini design in this podcast starting here:
https://youtu.be/kTpmiK5p_Wc?t=1152

New owners are making some improvements:
https://youtu.be/kTpmiK5p_Wc?t=1923

[Svgeesus]

For the (now discontinued) PDVS2, the manual says that there is a simple ascii protocol available on request. I have one of these, and would like to be able to program a fairly complex sequence of voltage steps far beyond the 5 steps provided by the windows electable. Is that still available or would I need to contact the new owners of the PDVS2mini?

I'm very happy with this as a manually-programmable voltage source, but (in contrast to the observation in the podcast that "everyone was just using it for it's basic functionality" I also want to use it in an automated test setup to examine the performance of voltage-controlled oscillators; this requires around 100 steps for a full test.

[IanJ]

Go to my website, online shop and look up the manual for the PDVS2mini, the comms protocol is published there……which is almost identical to the PDVS2.
I will provide the actual protocol for the PDVS2 on this thread later today.

[Svgeesus]

Perfect, so <KeyVoltage,0,1.23456> is all it takes in terms of commands(!) wonderful

[IanJ]

Perfect, so <KeyVoltage,0,1.23456> is all it takes in terms of commands(!) wonderful

There are slight changes depending on firmware version, but here's the protocol text doc for the PDVS2.

Code: [Select]

PDVS2 Serial Protocol (PVDS2 firmware 3.00)
===========================================

INTERFACE = USB (FTDI USB Drivers - http://www.ftdichip/Drivers/VCP.htm)
BAUD: 250k,N,8,1
A simple bi-directional ascii based serial data protocol
Rate = Data from PDVS2 to PC is sent every 110mS

Format to PC:- VR0,0,12345
Format from PC:- <KeyVoltage, 12, 1.23456>

The following details all the data being sent from the PDVS2, and only a partial listing of the data from the PC.


PDVS2 OUTPUTS TO PC:
========================
KV,0, Output Voltage of PDVS2
BV,0, Battery Voltage or DC Input Voltage
BVFM,0, Battery Voltage Feed Mult
OVF,0, Output Voltage Feedback
OVFM,0, Output Voltage Feedback
dacZ,0, DAC Zero Cal
dacS,0, DAC Span Cal
BC,0, Message = DC Input - Charging, DC Input, DC Input - Full, Running on Batteries, Battery Charge high mA!
BLI,0, Message = Status - Low, Status - Ok
Mode,0, Message = Main Menu, Normal, Calibration, Settings, Playback, Ramp

VA0,0, Volts Auto Set[0]
VA1,0, Volts Auto Set[1]
VA2,0, Volts Auto Set[2]
VA3,0, Volts Auto Set[3]
VA4,0, Volts Auto Set[4]

TA0,0, Time Auto Set[0]
TA1,0, Time Auto Set[1]
TA2,0, Time Auto Set[2]
TA3,0, Time Auto Set[3]
TA4,0, Time Auto Set[4]
AC,0, Autocount
AMR,0, Message = Running, Stopped

VR0,0, Volts Ramp Set[0]
VR1,0, Volts Ramp Set[1]
VR2,0, Volts Ramp Set[2]
VR3,0, Volts Ramp Set[3]
VR4,0, Volts Ramp Set[4]

TR0,0, Time Ramp Set[0]
TR1,0, Time Ramp Set[1]
TR2,0, Time Ramp Set[2]
TR3,0, Time Ramp Set[3]
TR4,0, Time Ramp Set[4]
RC,0, Ramp count
RMR,0, Message = Running, Stopped

BMIM,0, Battery Monitor IC Mult
BI,0, Battery current
AL,0, Autoloop
RL,0, Ramploop
SC2,0, Seconds2
dacZ2,0, DAC Zero Cal Dac2
dacS2,0, DAC Span Cal Dac2
VRS,0, Vref Switch
CMS,0, Cal Mode Sub


OUTPUT FROM PC TO PDVS2:
========================
<KeyVoltage,0,1.23456> Voltage requested to output from PDVS2
<VrefSet,0> Vref setting, 0=10v mode, 1=2v mode


Ian Johnston


[ComradeXavier]

I fumbled my PDVS2mini taking it off the shelf and dropped it onto my bench. Thankfully, it seems to have survived undamaged. I decided its front panel needed some protection from me (and also from the dust that settles on anything I don't touch twice a day).

This case has a nice close fit, a satisfying magnetic closure, and a storage slot so I don't lose the charging cable. (I should find where I stashed the cal sheet and stick that in there, too.) I used PETG for impact resistance and strong layer bonding.





If anyone has the same butterfingers problem and wants to make their own, I've attached the .step file.

Hardware is:

• M2.5x25 with nylon lock nut, qty 2 (for hinge pins)
• 6x2.7 mm magnet, qty 4 (commonly sold as 6x3 mm, I designed for the actual thickness of the ones I have)

[wrytech]

Time for an official update on the PDVS 2 Mini!

In the past weeks and months since I have taken over the design from Ian a lot of things happened and thus the PDVS 2 Mini is on a good way to make a return under the newly created wrytech brand.

The tasks at hand always alternated between the technical things to ensure that my version will be up to the standards set by Ian and managing all things business related and bureaucratic - with the latter being a lot more involved than expected (who would have thought?).

Today I picked my 3458A back up from calibration at ab-precision and it is very comfortably within the 90-day spec for DCV and with that the last open thing from a technical side is taken care of. The first 50 boards of the version 1.6 have been here with me for a couple weeks with everything working smoothly, also thanks to the constant exchange with and inputs from Ian.

Changes for the new version 1.6 include:

• Maximum output voltage increased to 10.22222V from 10.00000V with additional calibration point
• Addition of an internal temperature sensor
• Updated optics on the front panel and slight changes on the PCBs for improved manufacturability (reverse mount LED for the comms indicator for example), all critical analogue circuitry remains completly unchanged

Other than that, everything stays the same; all remaining stocked parts, test jigs, etc. have been taken over and as stated already the goal is to continue seamlessly where Ian has left off.

For now, one official matter is outstanding, but should be done in the upcoming weeks and the units can go on sale then.

To sign up for the newsletter head over to wrytech.eu. Updates will be posted here as well and any questions are more than welcome, of course.

Thanks again to Ian for the continued support and feedback provided,
Johannes

[IanJ]

All the best Johannes and Wrytech going forward. The PDVS2mini is in good hands.

Ian

[skander36]

Hi! Alll the best in the start of this takeover of an already success product!
My question is if you will take care of the support for the old ver.(calibration, repairs)?
Thank you!

[aronake]

10.2222 Volt is a nice upgrade!

How is the temperature sensor implemented?

If digital readout by the software, then that opens up for the idea of having say 3 calibration curves, one at 17C, one at 23C and one at 29C then interpolate between these to eliminate much of temperature coefficient of that output. That would be a super cool feature and should not be too difficult to implement if digital temperature sensor is there.

[aronake]

ah, looking at the pictures i see now that there is digital readout on the display. great!

[tatel]

Looking forward to get one of these. Having to send it out of the EU to calibrate, etc, was the bump in the road for me. But if it can be done within the EU, then I want one...

Best wishes

[J-R]

I also would like to know about obtaining calibrations for the previous model.  It also would be nice to have a US-based option.

[wrytech]

Thanks for all the feedback and input provided already, very nice to see!

To answer the questions and open points brought up:

• I will of course also provide (re)calibration and adjustment if needed / wanted for the PDVS 2 Mini and its predecessors.
  I can also do a firmware update in the process to extend the output of earlier versions to 10.22222V with the additional calibration point as well if wanted, leaving the temperature sensor then as only difference to v1.6.
• Same goes for repairs for the PDVS 2 Mini - as stated, I have taken over the complete stock of parts from Ian, so I can do exact repairs for previous versions even if components are different now
• The temperature sensor used is a TI TMP112A, with the current value shown on the display. Have not gotten around to add the temperature value to the serial communication protocol, but will do so going forward. Another thing might be a small indicator to show when the unit should have warmed up, as there is around a 10 K temperature difference to ambient once fully warmed up, which takes about 30 mins to settle if the unit was turned off before.

Thanks and Best,
Johannes

[cmu2017]

Hi Johannes,
And when can we expect the first ones for sale?

[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

[SHF]

I treated myself to the ADR1399 version, very nice device, works excellently!

[wrytech]

Firmware v1.2 is now available for download under the Resources tab on the website:

https://www.wrytech.eu/pages/resources

A PDF file with upgrade instructions and a changelog is also provided.
Additionally, the manual has been updated to include information on the new features introduced in this firmware version.

Best,
Johannes

[tonyalbus]

Received mine yesterday, the ADR1399 version... video review coming soon, but i needed to play with it. could not help to share it.
Yeah that feels great, my meters are good!! Yes! Yes!!!



(yes its not horizontal, but that is just quickly for the picture)

[tonyalbus]

What software are you guys using for your PDVS2mini for remote control ?
have not connected mine yet, but i have the isolated adapter,

i have been looking for the software from the screenshot from Ian, but i can't find it . (PDVS2mini 20bit V1.0)
also for calibrating the device (calibration for now not needed but who knows for later)

i did found some from other:
https://github.com/DunningtonAudio/PDVS2miniApp

Or for the old one from Ian: (but that is for the older 18 bit i guess prob not to use for this one)
https://www.ianjohnston.com/index.php/onlineshop/handheld-precision-digital-voltage-source-v2-detail

Or are you using something completely different?

[J-R]

I suppose there will need to be an update to the software to support the 10.22222V output and perhaps some other aspects?

But you could try Ian's Windows software: https://web.archive.org/web/20240617223338/https://www.ianjohnston.com/images/stories/IanJ/VoltageSourcePrecision/PDVS2mini/PDVS2mini.zip

[tonyalbus]

I suppose there will need to be an update to the software to support the 10.22222V output and perhaps some other aspects?

But you could try Ian's Windows software: https://web.archive.org/web/20240617223338/https://www.ianjohnston.com/images/stories/IanJ/VoltageSourcePrecision/PDVS2mini/PDVS2mini.zip

Thanks!  Yes the intrnet archive, i forgot.  Great that was what i was looking for.
Ian made some great software for GPIB and just watched an old video how he automated the whole bulk calibration for the PDVS, very impressive stuff.

[Cyclotron]

I received my unit yesterday. I regularly get things from mainland China faster.  I'm not lodging a complaint; it's just an observation.
I highly suspect that the holidays and maybe even Canadian post being offline have impacted global shipping. I ordered a KWeld board out of Toronto that should take 2-3 days to Virginia, and it took 2.5 weeks via FedEx.

Okay, what a nice device! I immediately did what most people, I figure, will do: I hooked it up to every meter I had to check its accuracy. I'm happy to say my primary two bench meters are perfect or thereabouts.
That means the recent calibrations I've made are likely good.

I have noticed a behavior I haven't seen reported, and I wanted to mention it here for WRY TECH and others.

I charged mine overnight, and this morning, I was nerding around with it (definitely not fondling).  I turned it off and set it aside when I realized I wanted to check the firmware version.
I clicked the power button, and the display showed the images in the attached photos. My stomach sank a bit. I think I clicked the button for more time, and it came to life normally.

In the end, I can reproduce the results easily. If you just tap the power button the display will pop up some lines and slowly clear. I suspect there's some logic in there that prevents bumping the device and changing the power state. But I'm not sure.

[IanJ]

I received my unit yesterday. I regularly get things from mainland China faster.  I'm not lodging a complaint; it's just an observation.
I highly suspect that the holidays and maybe even Canadian post being offline have impacted global shipping. I ordered a KWeld board out of Toronto that should take 2-3 days to Virginia, and it took 2.5 weeks via FedEx.

Okay, what a nice device! I immediately did what most people, I figure, will do: I hooked it up to every meter I had to check its accuracy. I'm happy to say my primary two bench meters are perfect or thereabouts.
That means the recent calibrations I've made are likely good.

I have noticed a behavior I haven't seen reported, and I wanted to mention it here for WRY TECH and others.

I charged mine overnight, and this morning, I was nerding around with it (definitely not fondling).  I turned it off and set it aside when I realized I wanted to check the firmware version.
I clicked the power button, and the display showed the images in the attached photos. My stomach sank a bit. I think I clicked the button for more time, and it came to life normally.

In the end, I can reproduce the results easily. If you just tap the power button the display will pop up some lines and slowly clear. I suspect there's some logic in there that prevents bumping the device and changing the power state. But I'm not sure.

This is caused by not holding the power button down long enough when you want to power it up.
The soft power circuit is integrated into the software, so when you just quickly jab the power button it does send 3.3Vdc to the display & uController but not long enough for the software to run and interact with the soft power switch hardware in order to hold the power on permanently.

The proper way to power up is to hold the power button for a second or so.....then release.

There's nothing wrong with your PDVS2mini.

Ian.

[glitchcatcher]

In the end, I can reproduce the results easily. If you just tap the power button the display will pop up some lines and slowly clear. I suspect there's some logic in there that prevents bumping the device and changing the power state. But I'm not sure.

It's perfectly normal behavior. IIRC it's written in the manual that you have to hold the power button to turn it on.
It's either against accidental power on as you say, or the µC is disconnected from the battery by that push button, and holding it down energizes the circuit and it takes some time to initialize and bypass that button electronically so the device stays on. That would be a power saving feature then which is just a guess. Wondering if that's still necessary with todays µCs standby/sleep currents.

[Cyclotron]

The proper way to power up is to hold the power button for a second or so.....then release.

There's nothing wrong with your PDVS2mini.

Ian.

Yup, that's what I figured, and I just didn't communicate well in my post. I only posted about it in case others saw it, and, as I did, a mild panic attack.  I prefer it like it is; as you said, there is nothing wrong with it.

[wrytech]

Finally following up on the things that came up over the holidays....

What software are you guys using for your PDVS2mini for remote control?

I typically use the Arduino IDE’s Serial Monitor for quick testing or custom Python scripts for more complex tasks. The latter also inspired the changes in software version 1.2, making it easier to reliably retrieve data (mainly temperature) using the “request” option.
I’ve mentioned before that I feel the serial connection is underutilized, likely due to the lack of examples and showcases. It’s on my list to address, but other tasks have taken priority for now.

That said, I encourage you to explore the commands—it’s as simple as opening the Arduino IDE’s Serial Monitor, connecting a PDVS 2 Mini, and sending <KeyVoltage,0,1.23456> to set the voltage to 1.23456 V.

Beyond calibration, I  also use the serial connection to remotely set the voltage on my Agilent E3616A supply, which only accepts control voltages and lacks a direct digital interface. I have used this to simulate battery discharge over a longer time period for example.

I received my unit yesterday. I regularly get things from mainland China faster. I'm not lodging a complaint; it's just an observation.
I highly suspect that the holidays and maybe even Canadian post being offline have impacted global shipping. I ordered a KWeld board out of Toronto that should take 2-3 days to Virginia, and it took 2.5 weeks via FedEx.

Shipping has been challenging because I handle low volumes, which made setting up logistics difficult initially due to minimum quantity requirements. DHL ended up being the best option here. However, since the packages transition through both national postal services, delays are sometimes unavoidable.
Tracking is included with all shipments, and so far, there haven’t been any major issues, with successful deliveries from Alaska to New South Wales. Still, I’ll look into adding an express shipping option that DHL already offers.

Recently, I introduced a cheaper rate for shipping links and the IUSL using “Warenpost International.” So far, this has only been announced in the newsletter.

I have noticed a behavior I haven't seen reported, and I wanted to mention it here for WRY TECH and others.

I charged mine overnight, and this morning, I was nerding around with it (definitely not fondling). I turned it off and set it aside when I realized I wanted to check the firmware version.
I clicked the power button, and the display showed the images in the attached photos. My stomach sank a bit. I think I clicked the button for more time, and it came to life normally.

I’ve noticed streaks on the LCD when turning on devices for the first time after mounting the display in some cases as well. I suspect this is due to stray voltages in the display that take time to dissipate. This issue can also occur if the batteries are removed without switching the unit off. It can take some time for the streaks to disappear, but so far, I haven’t encountered a display with any permanent marks or damage.

As Ian has already kindly mentioned, there’s absolutely nothing to worry about.

Let me know if there’s anything else you’d like me to clarify or address,
Johannes

[IanJ]

I’ve noticed streaks on the LCD when turning on devices for the first time after mounting the display in some cases as well. I suspect this is due to stray voltages in the display that take time to dissipate. This issue can also occur if the batteries are removed without switching the unit off. It can take some time for the streaks to disappear, but so far, I haven’t encountered a display with any permanent marks or damage.

Yes, I noticed that also sometimes......I.E. if I remember correctly, on the very first boot fresh from the reflow oven and after the firmware is loaded, the Flash ram area in the uC doesn't contain it's default parameters yet and so the LCD can be a bit random and doesn't clear at boot. It could probably be coded around that in setup() but it's only ever going to happen once in it's lifetime......unless the user as per here jabs the power button.

Ian.

[Cyclotron]

but it's only ever going to happen once in it's lifetime......unless the user as per here jabs the power button.

Ian.

And now I've been called a "user".  Oh man, that stings a bit. I've been an engineer and an Architect in Information Technology for nearly 30 years. "USER" has always been a 4 letter word.

I guess we are all users at some point.

[tonyalbus]

Here it is on my desk, the change of weather or the wind blowing the other way, coused my last digit not to match in the video
but man, the thing is clean and stable...

[ITArchitect]

These are sold out, when will the next batch be available?

[SHF]

now available again