This device is a digital USB voltmeter that allows you to measure voltage automatically. It can provide quite accurate digital measures for low DC voltage (0.01 Volt accuracy), but works as well for higher voltage, including AC, up to 250V (RMS), with an accuracy of 3%.

This device is isolated, which means that the sensor part is electrically disconnected from the USB part: you can measure any voltage difference between -250V and 250V, without risk of frying your computer.
The modules provides immediate reading on USB, and can also store measures on the device internal flash for later retrieval when connected again by USB.

This device can be connected directly to an Ethernet network using a YoctoHub-Ethernet, to a WiFi network using a YoctoHub-Wireless-n and to a GSM network using a YoctoHub-GSM.

Yocto-Volt Yocto-Volt Yocto-Volt

USB cables and enclosures to be ordered separately.

CHF 68.86

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Hardware release:Rev. C
Product name:Yocto-Volt
USB connector:micro-B
Refresh rate:10Hz
Input impedance:>660KΩ
Measuring range:-250...250V DC/rms
Accuracy:0.01V / 0.5%
Max working voltage:250V r.m.s.
Accuracy (AC, 50Hz/60Hz):0.1V / 1%
Accuracy (DC):0.01V / 0.5%
Sensitivity:0.01V 0.2%
Measurement category:Cat II
Protection class, according to IEC 61140:class II
USB isolation, clearance dist.:4.5mm
USB isolation, creepage dist.:3 + 2.6mm
USB isolation, dielectric strength (1 min.):1.5kV r.m.s.
Normal operating temperature:5...40░C
Extended operating temperature2:-30...85░C
Supported Operating Systems:Windows (PC + IoT), Linux (Intel + ARM), macOS, Android
Drivers:Driverless, no driver needed
API / SDK / Libraries:C++ Obj-C C# VB.NET UWP Delphi Python Java Android LabVIEW
API / SDK / Libraries (TCP only):Javascript Node.js PHP
RoHS compliance:RoHS III (2011/65/UE+2015/863)
Suggested enclosure:YoctoBox-Long-Thick-Black
Harmonized tariff code:9032.9000
Made in:Switzerland

1 These specifications are for the current hardware revision. Specifications for earlier revisions may differ.
2 The extended temperature range is defined based on components specifications and has been tested during a limited duration (1h). When using the device in harsh environments for a long period of time, we strongly advise to run extensive tests before going to production.

Accessories and related products

YoctoBox-Long-Thick-Black, Enclosure for Yoctopuce device (long, thick, black)Micro-USB-Hub-V2, Micro USB hub (multi-TT) with solder pads, for DIY useFix-2.5mm, screws and spacersUSB-A-MicroB-50, USB 2.0 type A to Micro-B data cable, 50 cmYoctoHub-Ethernet, Ethernet-enabled hub for Yoctopuce modules

Related articles and application examples


User manual (HTML)
User manual (PDF)
Product brief
3D file (STEP)
RoHS certificate
REACH certificate
Most recent firmware52890 (01/25/2023)
Programming libraries60664 (04/22/2024)
Command line API60664 (04/22/2024)
VirtualHub application59547 (02/28/2024)

Add a comment 33 comments

1 - chris j Friday,april 25,2014 17H15

WOW! I've been looking for this product for years. This seems to be the only one of its kind. I can't wait to get one. The Visual .NET support will be extremely helpful!

2 - matter45 Thursday,may 22,2014 3H17

bought the 5v version. needed to measure millivolts. feeding amp readings into pc, and pc is looking after batteries/solar/generator. its been working since Feb2014. the manual for visual basic was extremely helpful including the high level API. I hope you guys come up with a 500v version as well, i need it! Would also be nice to have a 200mv version for better millivolt accuracy over the 5v version. appart from that, very satisfied with the purchase. Highly recommend!

3 - martinm (Yocto-Team)Thursday,may 22,2014 5H48

@matter45: thx for your nice comment. There is no plan for a 500V version, but you could use a small transformer and the Yocto-Volt calibration feature (see user manual, Advanced programming chapter). Regarding the 200mV version, your wish might be granted pretty soon :-)

4 - huntfalow Thursday,january 29,2015 22H38

Hi just wondering but does anyone know if this device comes with the measuring prongs used to measure the voltage?

5 - martinm (Yocto-Team)Friday,january 30,2015 6H06

@huntfalow: nope, no probe included. You get the electronic board only.

6 - chris j Tuesday,february 03,2015 16H27

Any plans to release a PCI Express mini-card version? That would be sweet-- I could install it in my laptop and leave it there.

7 - martinm (Yocto-Team)Wednesday,february 04,2015 7H30

@chris j: It's an interesting idea, but no.

8 - chris j Tuesday,march 31,2015 17H12

I want to use this in VBA (Excel), but the DLL needs to be compiled as "COM visible." I don't have access to Visual Studio-- could you do it for me? Here's a quick how-to: http://www.geeksengine.com/article/create-dll.html

9 - chris j Tuesday,march 31,2015 17H44

Forget that previous comment -- I found something in the blog that will help me. Thanks!

10 - dbug Thursday,august 25,2016 18H33

Is the reading of the voltage permanent, or does that happen only when the value is requested?

I'm wondering if having the device permanently connected could not have a negative effect on the rest of my installation, like upsetting the solar-controller/charger, or possibly drain the battery?

Basically I have a Camper Van, and I need to remotely check the status of the batteries (24v AGM) and in case of problem send a notification, but I would rather not have the check itself make the problem happen faster :)

11 - mvuilleu (Yocto-Team)Friday,august 26,2016 5H20

@dbug: The voltage input is not switched, so it always stay a very small amount of current on the measured object. How much ? The Yocto-Volt has a 330 KOhm impedance, so current = 24 V / 330 KOhm = 0.073mA, so the voltmeter would drain a 10Ah battery in 137'000 hours or 5700 days.

If you want to completely avoid that effect, you can work around this issue by using a Yocto-Relay to connect the voltmeter to the battery only at the time you perform a measurement. Or, you can add a 3 MOhm resistor between the Voltmeter and the battery to create a voltage divider that will divide the measure by 10, the measured value by 10 and the stealed current by 10 as well.

12 - anges Tuesday,may 09,2017 9H53

Dear Sir, it's possible Yocto-Volt connect to Arduino board?

13 - martinm (Yocto-Team)Tuesday,may 09,2017 9H58

@anges: No. Mainly because Arduino boards dont have USB host support.

14 - mrd Wednesday,may 31,2017 18H35

This device is really great! I'm using it to detect when an intercom speaker becomes active (makes a buzz). It works very well, but I've run into a small issue that perhaps the API developers can help with. When I daemonize my code in python, I see the device arrival and removal happen and then it stops working correctly. I assume this has something to do with the fork and USB device permissions. I am running as root though. Please help if you can.

2017-05-31 14:15:59,677 - __main__ - INFO - May 31 18:15:59
2017-05-31 14:15:59,677 - __main__ - INFO - Device arrival : VOLTAGE1-90A2B
2017-05-31 14:15:59,678 - __main__ - INFO - - VOLTAGE1-90A2B.voltage2
2017-05-31 14:16:02,003 - __main__ - INFO - Device removal : VOLTAGE1-90A2B
2017-05-31 14:16:02,003 - __main__ - INFO - VOLTAGE1-90A2B.voltage2: 0 !INVALID! (new value)

15 - mrd Thursday,june 01,2017 1H11

I figured out my issue. I needed to instantiate the yocto API after the daemonization.

16 - martinm (Yocto-Team)Thursday,june 01,2017 5H18

@mrd: ok, next time just contact Yoctopuce support directly. :-)

17 - wiz Tuesday,october 03,2017 16H50

Hello, Can I connect ifiok_okonna@yahoo.com Yocto-Volt to raspberry pi?

18 - martinm (Yocto-Team)Tuesday,october 03,2017 17H13

@wiz: Yes you can, have a look at this:

19 - wiz Tuesday,october 03,2017 17H26

Sweet! Thank you very much. You guys have put an end to my search :)

20 - cjw Monday,january 13,2020 19H13

Looking into building an LPM with this device with an Ophir 20Y-1-A sensor, however will the configuration allow me to change units directly in firmware?

1V=1000mW/1W of output

Thank you for your response

21 - martinm (Yocto-Team)Tuesday,january 14,2020 6H26

@cjw : what is the voltage ouput range of this Ophir 20Y-1-A sensor? if it's less than 10V, a Yocto-0-10V-rx might be a better choice. Feel free to contact Yoctopuce support directly for further discussions.

22 - cjw Tuesday,january 14,2020 17H43

The Ophir sensor requires 20V to work the full range of the input capability, so the Yocto-0-10v-Rx would only allow 10W of measurement.

1Vdc : 1W of optical input --

23 - martinm (Yocto-Team)Tuesday,january 14,2020 18H45

@cjw : you can use the Yocto-Volt internal calibration system to map measured values to whatever you want. But you won't be able to change the unit. The device will always report the unit as Volts.

24 - cjw Thursday,january 16,2020 5H51

By Internal calibration you are meaning the firmware... but I can't change the reported units. So this will always report as volts or mV. This is what you are explaining?

I'm after something I can change the reported units, taking a mV or V reading and report into a given unit but that can go to 20Vdc input. I'd like to be able to dump the output into a .CSV file or using the gauging in Yocto-graph.

25 - martinm (Yocto-Team)Thursday,january 16,2020 6H17

@cjw: Yoctopuce firmware source code is not public. But all Yoctopuce sensors feature a user configurable calibration system, see www.yoctopuce.com/EN/products/yocto-volt/doc/VOLTAGE1.usermanual.html#CHAP21SEC3 You will find an example with proper user interface called Prog-Calibration in C#, Delphi and VB libraries. There is also the article about calibration with a web based tool here: www.yoctopuce.com/EN/article/calibrating-a-yoctopuce-sensor

That being said, in the case of the Yocto-Volt, one cannot change the reported unit, ie the get_unit() function will always return "V" no matter the calibration. I believe this is not really in inconvenience if you plan to dump data in a CSV file, worst case scenario a simple search and replace will do the trick.

26 - cjw Saturday,january 18,2020 8H02

Thank you for the detailed explanation regarding the Yoctovolt! I see what you are saying now.

I was also hoping to using Yocto-Graph to report voltage to mW / W in real time when testing various Class IIIb and Class IV laser diodes with an Ophir 20C LPM.
.CSV exporting is also just as important.

My only hope seems like the 10V sensor module at this point.

27 - brunozp Tuesday,august 01,2023 22H23

Why does this module has 2 voltages in the api response if it only has one input ?

28 - martinm (Yocto-Team)Wednesday,august 02,2023 4H31

@brunozp: voltage1 channel is for DC and Voltage2 is for AC. More details can be found in the user manual:


If you need to find out which one is what by software, use their get_unit() method.

29 - sal Thursday,april 25,2024 22H17

After adding yocto_voltage.cs to my exising VS project and installing the Yoctopure.YoctoLib with nuget manager, I have (2) errors in yocto_voltage.cs:

in the get_enabled() function:
"YAPI" does not contain a definition for '_yapiContext'

In the FindVoltage() function:
"YAPI" does not contain a definition for 'globalLock'

Please advise how we can fix this. Thank you.

30 - sal Thursday,april 25,2024 22H20

Sorry, we just removed the yocto_voltage.cs function from the project and the calls to the components that we need work from the NuGet package we installed. Please ignore my last post.

31 - roverdog Thursday,april 25,2024 23H49

Is this device CE certified?

32 - mvuilleu (Yocto-Team)Friday,april 26,2024 7H59

@roverdog: the product has been designed to satisfy all essential requirements for CE marking as part of a solution for laboratory equipment, industrial process-control equipment and similar applications in residential or commercial environment. Send a mail to support if you need a copy of the EMI test lab results. Be aware however that the Yocto-Volt itself is however just one part of your solution, and the CE mark process requires that you assert the compliance of your solution as a whole, including the enclosure, the interconnects, etc. as there are many factor exterior to the Yocto-Volt that can affect compliance with the standards.

33 - mvuilleu (Yocto-Team)Friday,april 26,2024 15H59

In case someone hits the same problem: the problem reported by @sal just above was caused by manually adding a recent version of the file yocto_voltage.cs while an older version of the base library was installed via nuget. Removing the added file was enough to solve the problem.

In case you hit a technical issue of this kind, don't hesitate to send a mail to support@yoctopuce.com

Yoctopuce, get your stuff connected.