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Handheld Precision Digital Voltage Source - PDVS2 - RETIRED NO LONGER AVAILABLE

A handheld Precision Digital Voltage Source, true 0.0000V to 10.0000Vdc range, battery powered.

Handmade in Great Britain

Unlike anything else on the market this is a truly handheld Precision Digital Voltage Source. 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.

NOTICE: The PDVS2 is no longer available and has been superseded by the PDVS2mini.
The PDVS2mini is my new 20bit unit and is available here.


EEVBLOG Starts The Ball Rolling:-
I sent Dave Jones an early PDVS1 prototype unannounced for his Mailbag, it looked like it was greatly received! Video here . So, I pushed forward with the design and made many improvements. Better stability, Less noise on output, Better quality banana sockets, better user interface, Internal sense line to banana's, MAX6350 Vref dropped for an LM399AH and more.
Martin Lorton Confirms Hard Work Has Paid Off:-
With the PDVS1 in production I sent one over to Martin Lorton where he turned out a great independant review of  the unit, link to his video here. But it didn't stop there because not long after in another video Martin used the PDVS1 to help him repair his own HP3458a 8.5 digit multimeter! Video here.

Changes for 2019:-
- Indented Rotary Shaft Encoder, each 'indent click' is 1-digit change
- Updated Firmware (V3.0): Better response from the Rotary Shaft Encoder & Rotary push switch
- Minimum output voltage in 2V mode now 1mV (was 10mV). Minimum in 10V mode remains at 0V.
- New Pcb: Better filter on vref & power sections, better isolation between digital & analogue sections, extra protection on final output, 2oz copper layers


  • True 0 Vdc to 10 Vdc user adjustable output in 10 V mode (4d.p’s effective, approx. 38uV)
  • 2nd mode giving 0.001 Vdc to 2.0 Vdc user adjustable output (5d.p’s effective, 10 uV)
  • Voltage setting or ramp up/down controls via the 12 button numeric keypad
  • Digital Rotary Encoder allowing quick, on the fly adjustments of the output voltage
  • LED backlighting
  • Soft power switch
  • Extension PCB on back of the banana sockets to facilitate a good mechanical layout
  • Based on the industry standard LM399AH (0.5 ppm/degC) voltage reference
  • All digital calibration, no internal potentiometers
  • 18bit DAC with an accuracy/stability down in the uV’s (using a PLC filter of 1.0 or higher)
  • Battery voltage monitor, including low voltage warning, auto-shutdown and charging status
  • Output voltage monitor including short circuit protection
  • 3” Graphics Monochrome LCD (128x64 pixels)
  • Atmel Atmega1284 micro-controller (uses Arduino bootloader)
  • Precision chopper op-amp on final output and using low tempco resistors
  • Re-calibration by the user possible via keypad/LCD
  • Charging pcb/socket for Li-ion batteries using a battery management IC. Batteries/DC adaptor are not supplied
  • USB port for remote operation via Windows application
  • Battery reverse polarity protection
  • Fire retardant (UL 94V-0) ABS Hammond case, aluminium anodized & engraved front panel, 4mm banana sockets, 4off adhesive feet
  • Manual including factory calibration/settings test record. Unique serial number
  • Software function- PLAYBACK mode & RAMP mode
  • Software function- Remote Operation via Windows app (via new USB port) - Mini USB cable not supplied
  • CE approved

Link to the project page (PDVS1) with tests and design data, and link to a comparison made with other portable voltage references.
Prior to shipping each unit assembled & tested in-house, aged/burned-in for 170hrs and calibrated with a HP3458a 8.5 digit multimeter (Keysight Cal. 08/03/19) at constant ambient temp.
In the box - 1off PDVS2 (no batteries, no charger), adhesive feet, 1off Charging connector c/w tail, Calibration record and details of the PDF Manual (c/w CE Declaration of Conformity) & Windows app downloads.

NOTICE: VAT is not payable by purchasers outside the EU, AND, by purchasers in the EU (excluding UK) who are VAT registered, please contact me prior to purchase to receive instructions on how to zero rate the VAT.


  • Voltage reference = LM399AH (0.5 - 1 ppm/degC temperature coefficient)
  • 10V mode = 0.0000 Vdc to 10.0000 Vdc in approx. 38 uV steps
  • 2V mode = 0.001 Vdc to 2.00000 Vdc in 10uV steps
  • Load = 3kohm minimum. Example: At 10Vdc output with 3kohm load = 3.3mA (whilst maintaining output within approx. 10uV)
  • Accuracy = Within 100uV on both 2V & 10V modes. Typically 0.001% at 10V output, 0.005% at 2V output
  • Stability = 0.0001Vdc var. max. 4d.p. mode.  Stability = 0.00004Vdc typical var. in ext. 5d.p. mode. Orientation of the unit may effect output (calibrated horizontally)
  • Temperature coefficient (unit) = 2 ppm/degC typical (Actual test: 0.000018Vdc change over 8.8degC temp change, 45min duration)
  • Drift (12 months typical) = Sigma-ppm: 10V range: 0.77, 2V range = 1.69 (independently tested)
  • Stabilization time = 10mins to 1hr depending in ambient temperature and last use
  • Output short circuit = indefinite (24mA)
  • Power (batteries) = Two Lithium-Ion re-chargeable 9V PP3 batteries (Not supplied, 600mAh batteries recommended)
  • Power (external power)  = 18 to 24Vdc input (also charges the batteries) @ 400mA min recommended
  • Battery = Approx. 12hrs (EBL 600mAh re-chargeable batteries) typical continuous operation with backlighting off
  • Current drain = 50mA approx. (after 10mins)
  • Dimensions = 158mm x 83mm x 35mm (case size)


  • PDVS2 Windows App - V1.2 (02/06/17) for all firmware versions - Download here
  • PDVS2 Manual - V1.2 (27/04/17) for V2.02 firmware - Download here
  • PDVS2 Manual - V1.10 (26/10/17) for V2.03 firmware - Download here
  • PDVS2 Manual - V1.11 (08/11/17) for V2.05 firmware - Download here
  • PDVS2 Manual - V1.12 (23/12/17) for V2.07 firmware - Download here
  • PDVS2 Manual - V2.0 (30/03/19) for V3.00 firmware - Download here


Can be re-calibrated by the user.


We highly recommend 600mAH or better Li-ion PP3 batteries from EBC (I did a battery test here). These will give you 12-14hrs continous use between charges.
A DC adaptor or power supply is required (not supplied) to charge the batteries and should be rated at 18V - 25Vdc @ 0.4A. A compatible plug with tails is supplied.
Is the charging safe? - I have implemented a current-limited, switch-mode Li+ charger/controller and am running it quite low (0.25A charge current) to avoid any issues. The software also monitors the charge current and can shut it down.
The EBC batteries have protection circuitry built in as an added protection for under-voltage/over-charging.


The rotary encoder, USB port and the charging port visible on the side of the unit.

PDVS2 1a

A DC adaptor jack next to the batteries to power the unit from an external source and/or charge the batteries. You can see the charger Pcb under where the batteries sit.
The LM399AH voltage reference (large white package) stands out and the PP3 battery terminals. At the top of the photo you can see the mini Usb connector and the DC power connector.

PDVS2 16a

The banana adaptor pcb. The 3 connections are voltage out, 0Vdc and a sense line. The backlighing module (white) under the LCD is visible.

PDVS2 13a

Pcb top side. Here you can see the battery charging circuit below keyboard (not shown) and well out of the way of the main pcb. The rotary shaft encoder and on/off switch below the Lcd are visible.

PDVS2 14a

The main menu screen. You can also see the backlighting in operation.

PDVS2 2a

Main screen - 10v mode.

PDVS2 4a

Main screen - 2v mode. The 5th DP is now full size as 10uV resolution is attainable in this mode.

PDVS2 7a

PDVS2 5a

PDVS2 6a

PDVS2 18

PDVS2 17

PLAYBACK mode running.

PDVS2 19

RAMP mode running.

PDVS2 20

Windows app:



USER TESTIMONIALS (please send in yours!)

Robert from the USA says:

"Just wanted to let you know how very impressed I am with your voltage reference. I received an HP 3457A yesterday from eBay and immediately grabbed your reference. The meter reflected spot on measurements through all but the very last decimal place....very very impressive!  The HP may in fact be a little off.......Thank you again for a fantastic piece of high quality equipment."

USER PHOTOS (please send in yours!)

Mauri from Finland:

PDVS2 Mauri_34401a thumb PDVS2 Mauri ebd a20h thumb PDVS2 Mauri ut181a

Joe from the USA:

20170531 144655 20170531 144746

Paul from Germany:

PaulSchmid001 thumb PaulSchmid002

Torben from Denmark:


John from Seattle:

John Seattle1