Arduino Digital Multimeter


If you want to support this project you can make your donation here! Thank you!

Premium version 2.0.0 added

The new version 2.0.0 supports USB connection with OTG cable. For more information press the button “go to version 2.0.0”.


Arduino Multimeter is a project based on an Arduino microcontroller and a smartphone.  It is easy to do and does not require many components. Just follow the tutorials step by step and if you have any questions contact us. This multimeter will help you in many projects and it is also very comfortable to use! Do not be scared to see that you have to mount a circuit, everything is well explained. This multimeter is wireless and uses connection with smartphone by bluetooth (HC-05 or HC-06 bluetooth module). In the future I will also add the possibility of connection by OTG cable. This multimeter can be a good tool for people who like electronic projects. The multimeter has: Voltmeter, Ammeter, Oscilloscope, Resistor color calculator, Sound generator, capacitance meter, inductance meter and much more. I often add new functions. You have the possibility to use the premium functions using the points earned in the menu, in the “Earn points” section, which consists of watching short video ads. Each video you have seen gives you points that you can then spend to use some Premium features, or you can buy the Premium version and get access to all the functions and new features that will be added in the future. Functions of this multimeter are based on an Arduino microcontroller. Arduino measures Volts, Amperes e.t.c and then by bluetooth module (HC-05 or HC-06) sends the measurement to the smartphone. The oscilloscope is connected through a protection circuit to the smartphone through the headphone input. The multimeter also has a database to store the values we measure. To save we can give a name to the value that we are going to save and brief description. Then we can see the saved values when we need them. I also recommend subscribing to my blog and my YouTube channel so I can inform you when there are new updates or new projects. When you subscribe you will receive an email with notice when I publish a new project or update.  Start now and build your own Multimeter!

This multimeter has:

Components we need:

Cheap components from Aliexpress

Step 1: Pair the bluetooth module

The first thing we have to do is pair the bluetooth module that we are going to use. This we only do once and the module will be stored in the memory of our smartphone so we will not have to pair the bluetooth module every time.
If you do not know how to pair bluetooth module keep reading if you already have it paired or you already know how to do it you can skip this step. To be able to pair bluetooth module with our smartphone we must connect the power to the modul bluetooth, we can simply connect the GND of the bluetooth module to GND of the arduino and the pin +5 v of the bluetooth module to the pin 5v of the arduino. Once connected, we plug the arduino into our computer and the circuit will be powered. If all is well the module bluetooth light should  blinking  fast. To pair our module with smartphone we go to smartphone settings in the section Connections / Bluetooth and activate bluetooth (if it is disabled). When it is activated we press the Scan button. When smartphone finds our module we press the name of the bluetooth module and the pairing process will begin, in a few seconds it will appear that the bluetooth module is already paired. Ready, we have the bluetooth module paired with our smartphone!






Step 2: Set bluetooth module

Now we have to select in the Multimeter app the module that we are going to use. As we have already paired the bluetooth module, it will be in the list of paired bluetooth devices. We are going to select the bluetooth module in the app. First we must activate bluetooth to be able to select bluetooth module from the list, then after on the start screen of the app we selectSettings, we will open the Settings menu and in the list of settings we select “Set bluetooth module”, we will see the list of all the devices paired with our smartphone and we must choose the bluetooth module that we are going to use. Once selected it will be saved, we do not have to select again unless we want to use another bluetooth module.

Step 3: Let's assemble the circuit

Now let’s assemble the circuit. First we must choose where we will put the components to assemble the circuit, a protoboard or we will directly weld to a PCB. Next step is to prepare all the components that we will need, to have everything at hand. The list of components you will find at the beginning of this page and in the file that you can download below. Keep in mind that it is not necessary to mount the entire circuit for the multimeter to work. For example if you are not interested that the multimeter has an inductance meter or ohmmeter or capacitor, simply leave this part and the multimeter will work without these options, will only have the options you want. Below you will find two schematics one is how to mount the Multimeter and the other is the inductance meter that also connects to the arduino. Just look at the indications of the pins.

The circuit is divided into two parts: the multimeter itself and the inductance meter, in fact, is the same circuit and is assembled on a printed circuit board and divided for convenience. The most convenient option is to assemble a multimeter on a printed circuit board, since all that remains is to make a printed circuit board and place all the components. In the video you can see how the printed circuit board is made using the ironing method and how all the components are installed.

Cheap PCB from Aliexpress:

Additional Information

In order to obtain good precision of the measurements we must take into know several things. we can measure (with everything already connected) the voltage between pin 5v of the arduino and GND of the arduino and in the sketch put this value that we just measured. In the arduino sketch to put this value we look for the line of the code where it says: “float vin = 4.8f; // pin” 5v “SET EXACT VALUE HERE” and we change the value 4.8f for the value that we just measured. In this way we will have better precision. We can also improve more by entering the values ​​of the exact resistances. The values ​​of the resistances can vary, for example we have a resistance of value “100k” is not always so, we can measure the resistances and enter in the arduino sketch the exact values, this will give us even better precision. In the sketch you will find the indications to enter the exact values ​​for volts measurement and for ohm measurement. For measurement of volts we have two resistors “100k” and “10k”, and for measurement of ohms we have 3 resistors of “220”, “10k” and “100k”. Change these values ​​in the sketch by the exact values ​​and you will have better precision. Also try to avoid “parasitic” resistances because this can also lower the accuracy. To avoid the parasitic resistances you simply have to weld all the components to avoid bad connections. Before writing bad comments if you have any problems contact me I will try to help you, everything can be fixed and resolved! My email

Video tutorials:

How to assemble the circuit:

How to use Oscilloscope:

Other things from Aliexpress you may need

106 thoughts on “Arduino Digital Multimeter”

  1. esta bueno necesito la versión paga (pro) pero que se le pueda consignar el dinero de forma que no sea tarjeta crédito ni debito

  2. Hola Neco, podrías subir un video sobre el funcionamiento del detector de H de bobinas, estoy ensamblando el circuito, pero para decidirme comprar la versión pro de la aplicación me gustaría ver El funcionamiento del circuito, gracias!

  3. Hola Serjio, descargué multimetro pro para medir inductancias pero lamentablemente no muestra el valor medido, solo por instantes parpadea valores que van cambiando. También probé medir voltaje de una pila pero no muestra, solo sale 0.0v
    Agradeceré me digas que está pasando.

  4. Not able to upload the sketch to Adruino nano
    Error Prompts troubleshooting#upload

    Avrdude: stk recov not responding
    stk getsync not in sycn

    Kindly Help

    1. You need to make sure you set the right port and you set the right microcontroller. Please open the programm and i menu “Tools”
      Make sure in sevtion “Board” you set “Arduino nano”
      In section “Port” port you are connect arduino.
      If this not work contact ne at

      1. do NOT connect BT module when you do upload the sketch!
        BT is connected in parallel on Rx/Tx pins used for usb/serial adapter onboard, so… you can experiment some strange behaviors!

        – connect Nano to computer, alone
        – upload the sketch
        – disconnect Nano
        – do the required connections
        – put Nano in his socket
        – power up
        – enjoy! 🙂

        PS works fine with a Mini Pro, too… 🙂

        1. Thank you, but i don’t connect bluetooth module to Tx/Rx pin, i use bluetooth serial and i can choose pin i want to use. It only need to disconnect bluetooth module when you use Rx/Tx connection of the arduino board, but in my project it doesn’t.
          Thank you!

  5. Hi.. Can i ask if it is possible to make the osciloscope function connected with bluetooth and not hardwired to the headphone jack. Thank you

  6. من اصلاهیچی نفهمیدم اگرکسی بلدیاانجام داده کمکم کنه یابرم یه دستگاه بخرم دردسرش کمتره؟

    1. من انجام دادم واسه دوستانم حرف نداره دوست داشتی واست درست میکنم همه چیو ساپورت میکنه با باز کردن قفل سلف سنجش کامل میشه انجامدادم
      تهرانم 09361006636

    1. You can measure max 40 volts, but if you change resistance value you can get more than 220 volts
      The current it is depend of the shunt you use.

        1. You need open any web page to calculate the resistance values. Just write in google: ” Resistance divider calculator” and you will see lot of web page for calculate the resistance values.

  7. собрал схемку для осцилографа ,не работает.от встроенного динамика синусоида есть,от джека нет.пожалуйста подскажите.

    1. Проблема в штекере, на некоторых нужно поставить сопротивление на 1.4 кОм между общим штекера и микрофонным входом. Это зависит от производителя смартфона. Иногда помогает просто выдернуть несколько раз и вставить сново штекер,

    1. Because i put thd inductance meter schematic on the other page, you can see it below the arduino schematic just connect them together, you can see the numbers of conbection to arduino.

  8. Seitch will for chusing the rage for measuring of resistance. It is a switch wich connect one pin to 1 of 3 pines

    1. Hay que descargar Arduino sketch(lo tienes aquí, en mi pagina) luego descargar un programa que se llama Arduino IDE, esa programa ayuda a subir sketch a arduino. En el Programa seleccionamos la seccion Herramientas y donde pone Placa arduino elegimos la placa que tenemos. Luego conectamos el cable con arduino y le damos a subir, listo. En youtube tengo video tutorial

  9. hola, disculpa podrias subir un diagrama de conexion con el arduino UNO-R3?
    lo que pasa es que tengo duda en que pines conectar el modulo BT-HC-05
    de antemano gracias, saludos

    1. Los pines de arduino nano son como del arduino uno. Si en el esquematico pone D12 en arduino uno sera 12. Cada uno de los pines de arduino uno tiene su numero, y son iguales como en arduino nano, solo en arduino nano el numero va con letra “D” por ejemplo “D12” y arduino uno sin la letra “12”

  10. Hello,
    I have a question about cap selection. Not sure what to use for C1 & C2. Are both non polarity & what type (ceramic, metalized polypropylene, etc.)? Starting to source parts & looking forward to building. Thanks!

  11. Thanks for the info, I have another question. Having a difficult time sourcing R3 – 0.015 ohm shunt/sense resistor in std .25W – .5W size. What is the max power rating that is acceptable &/or is there another resistance besides 0.015 ohm that will work? Thank you!

  12. Hi,
    I need only ohm meter to detect resistance and recording facility with android display so which of these circuitry,sensors,and code I have to eliminate



    1. Here in my web page you can finde voltage divider, you have to calculate resistance to be able measure 80v.

      1. Nguyen Duy Thang

        I wnt calculate resistance to be able measure 300v voltage divider, Vout =? 3.6v or 3.3v. Thank you!

          1. Nguyen Duy Thang

            Thank you. How much amperes is measured range. What if I want to expand the measuring of resistor range up to 20M? please guide.

  13. I am using the FREE version of Arduino Sketch v1.00 to test. But pairing failed – “Pairing rejected by CC41-A. V1.00 comm connection is pin 5 & 6. While the v1.03 use pin 11 & 12. I tried both and it can’t pair.

    1. Hello, for pair bluetooth midule it must work anyway. It not important are connected pin Rx,Tx it must allow you pair divices. If you can not it can be problem of bluetooth module

  14. Hi neco.
    I been using Arduino-multimeter app for some time now and one I wish you add to your next update is the option of keeping the on (is prevent the screen from going to sleep.

  15. Tôi đã hoàn thành sơ đồ mạch đồng hồ và bây giờ chỉ còn kiểm định nó qua sơ bộ thì tôi thấy hoạt động tốt các thang đo riêng thang đo điện dung có vẻ hiển thị chậm nếu ở điện dung lớn

  16. Nếu mạch ngoài được được xác định để đo điện áp 220v vậy trong ứng dụng đồng hồ có hiển thị 220v không

    1. Yes it have this options. To use this option you need to set “speaker” in the app. And in arduino side resistance measuring block enough to use this function.

    1. Yes it have this options. To use this option you need to set “speaker” in the app. And in arduino side resistance measuring block enough to use this function

  17. I really like this project. I’m setting up a bench to begin building a robotic project and your meter/scope would be ideal for me. Sadly, I wish I had taken a foreign language while in school. The second video you did where you mounted parts to the pcb, I don’t understand what you are saying. As a hobbyist I could use some ideas on how to mount the pcb in a box permanently. I’m also wondering if I would have any issues running this on a Samsung Tab A tablet?

  18. Hello Neco,
    Would you please create scetch for esp32? It’s built in Bluetooth and more powerful. We are hurry to see it, thanks…

    1. I have test it but esp32 have a bad ADC. This make very bad measure. For example, i have test a 1.5 volts bettery but result is 1.3 volts and for bettery 5 volts result is 6.3 volts. There is not linear accuracy. In the official web page say may be un the features they will fix it. So, esp32 to make multineter is not good idea. But i now testing STM32 and it realy goid solution. Be cause it give very good accuracy, much better arduino, and it faster. So the next update will with STM32

  19. سلام
    اصلا کد کامل نداره برام بفرست من میخوام آردوینو کد کپی میکنم

  20. Bu sistemi osilaskop ve multimetre olarak kullanmak istiyorum. Hazır olarak satıyor musunuz? Çalışır vaziyette satın almak istiyorum.

  21. Hello Neco,
    I love this project, so I assembled it myself. I used a 2-Resistor Voltage divider between D11-RXD to ensure 3.3V signal.
    I checked the AO and A1 values, that these is real signal.
    However, the connections between my Android Phone and BT module does not work. I assembled the temperature sensor and the voltage measuring unit. The values on the phone are changing regadless reality.
    Can you please help with some tips, what to check to make ti work?
    If I succeed with this curcuit, I would like to give it more popularity and publish the concept in our National Practical Electronics Magazine – if you are interested.

  22. hola,¿cuantas mediciones por segundo puede hacer arduino?, y ¿cuál es la velocidad de transferencia del módulo bluetooth?, me gustaria hacer un oscilopio bluetooth para el movil y me gustaría saber hasta que frecuencia puede medir. Gracias.

  23. Excuse me sir I want to ask about the resistor value of inductance parameter. what is the right value? 330 ohm or 330k ohm? Thank you:)

  24. Excuse me sir I want to ask you about the resistor value of inductance parameter. What is the right value? 330 or 330k? Thank you:) because 330 in circuit image and 330k on component list

Leave a Reply

Your email address will not be published.