NEW PDVS2mini DC Voltage Reference from Ian Johnston - Reviewed.

[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.

[flo.b]

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)