Thursday, March 22, 2012

How to Make a Digital Voltmeter, Ammeter Circuit Module

Electrical parameters like voltage and current are inherently associated with electronics and with electronic engineers.
Any electronic circuit would be just incomplete without appropriate supply of voltage and current levels.
Our mains AC supply an alternating voltage at the potentials of 220 V, for implementing these voltages in electronic circuits we incorporate DC power adapters which effectively step down the mains AC voltages.
However, most power supplies don't include power monitoring systems in them, meaning the units don't incorporate voltage or current meters for displaying the relevant magnitudes.
Mostly the commercial power supplies use simple ways to display the voltages like a calibrated dial or ordinary moving coil type meters. These may be OK as long as the involved electronic operations are not critical, but for complex and sensitive electronic operations and troubleshooting, a hi-end monitoring system becomes imperative.
A digital volt meter and an ammeter become very handy for monitoring voltages and current perfectly without compromising safety parameters.
An interesting and accurate digital voltmeter and ammeter circuit has been explained in the present article which can be easily built at home, however the unit will require a well designed PCB for the sake of accuracy and perfection.
The circuit employs IC 3161 and 3162 for the required processing of the input voltage and current levels.
The processed info can be directly read over three 7-segment common cathode display modules.
The circuit requires a 5 volt well regulated power supply section for operating the circuit and should be included without fail as the IC strictly requires a 5 volt supply for operating correctly.
The displays are powered by individual transistors which make sure that the displays are lit brightly.
The transistors are BC640, however you may try other transistors like 8550 or 187 etc.

The complete circuit diagram link is provided in this ARTICLE

and HERE.


  1. Dear Swagatam,
    You have done a Excellent job, thank you for all your input's. Only today I found your blog, and was browsing for a "AVS circuit using an Isolation transformer", which would not have any break/delay (mS) while relay switching. I would prefer to use the control circuit on the primary of the transformer. Do you think you could help me?. Thanks a million.

    1. Thanks very much Basky, welcome to my blog!

      Please check out the following couple of links:

      If you have any further doubts, feel free to put them here:


  2. Hi Swagatam,

    do you have a circuit for digital AC voltmeter?


    1. Hi,

      Some interesting information has been provided in the following page, might be useful to you:


  3. Hi Swagatam,

    can you help me how to make a voltmeter circuit in using the breadboard??

    thanks a lot !!!

    1. Procure a breadboard then i'll explain how to proceed....

  4. Replies
    1. Please repeat your question I will answer it.

  5. sir can u provide overall circuit of digital a.c voltmeter having range 0-500v

    1. Please check the circuit here:

  6. hey swagatam,
    cant finf the circuit diagram in the link. pls can u re pose the site. thanks in advance.

    1. Hi Thila,

      Google this:

      "digital ammeter voltmeter circuit module" and go to images, click the first image.

  7. Hi Swagatam I am trying to measure Ac Voltage and current using Atmega32 and send the corresponding values to a remote user via SMS using a GSM module can you provide some assistance in this, I am stuck at voltage and current measurement part.

    1. Hi Shivendra,

      I am not good with microcontrollers so I am sorry I won't be able to help you.

  8. Hi Sir,
    This is Siddu
    Thanks for replying to my comments.
    As you said values R3 or 2 ohm/2w used same then also same its taking above 3hours for charging even without resistor also same problem when normal charging from AC charger it will take around 2hr only, so please gave me the circuit diagram which is working like AC charger and my mail id
    Even I am following urs all blogs past 10 months it become very helpful.
    Thanks a lot you and god bless you
    Like you such people in this world very rare and thanks once again to your being here :)

    1. Hi Siddu,


      Try using a LM317 circuit and through some trial and error find the correct voltage that will possibly give you the quickest charging rate..

      You can try the following design:

      Rc and BC547 can be removed....not required for your application.

  9. I will be waiting for your reply

  10. Hi sir
    Thanks for your comments
    After populating ckt I will be here along with result


Readers are requested not to include external links while commenting. For consulting a diagram, upload it on Google Drive and provide the link here.

Readers are advised to proceed with the construction of the presented circuits only after understanding the concepts from the core. Not adhering to this can lead to failures and frustrations.
Copyright © Swagatam Innovations. All rights reserved

Popular Posts