1. Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
    Dismiss Notice

Building a Digital Ammeter...

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by DavoNess, Nov 25, 2002.

  1. DavoNess

    DavoNess New Member

    Joined:
    Nov 25, 2002
    Messages:
    2
    Likes:
    0
    Ok using an ADC is no problem but how do I go about measuring a current between 0 to 50amps with a 0.1A scale ?

    Im sure no shunt resistors can take that kind of current so what other options are available to be able to do this ?

    Thanks in advance !
     
  2. mechie

    mechie New Member

    Joined:
    Sep 4, 2002
    Messages:
    591
    Likes:
    3
    Location:
    Lincolnshire, England
    High Current Measurements

    If you are measuring AC then you could consider a Current Transformer - take care as the secondary winding of these things can kick out amazing voltages if open-circuited.

    For DC I know of no alternative to shunts - if you have a car battery tested at a garage they will use a gizmo with a huge shunt to measure short-circuit ability. It looks like an inch-wide, two foot long strip of steel for the shunt.

    Could you use a hall-effect transistor strapped onto the side of a conductor and infer amps from magnetic field?

    .
     
  3. DavoNess

    DavoNess New Member

    Joined:
    Nov 25, 2002
    Messages:
    2
    Likes:
    0
    Hmm yea it is DC and the other trouble is not only measuring 50A but also with a resolution of like a 0.1A step size.

    Im actuall measuring the current coming out of a 500W computer PSU on the 12V, and 5V lines
     
  4. dave

    Dave New Member

    Joined:
    Jan 12, 1997
    Messages:
    -
    Likes:
    0


     
  5. Phasor

    Phasor Member

    Joined:
    Aug 14, 2002
    Messages:
    703
    Likes:
    0
    Location:
    Sydney, Australia

    I mentioned in another post about Hall effect devices. You could use one of these to measure DC current, but being a non-contact device, I'm not certain about it's accuracy.

    It is possible to buy Hall effect tong ammeters, which will read both AC and DC.

    EDIT: Sorry mechie - I didn't see that you already mentioned it :)
     
  6. kinjalgp

    kinjalgp Active Member

    Joined:
    Oct 28, 2002
    Messages:
    1,851
    Likes:
    3
    Location:
    INDIA/USA
    I have used Tong type ammeters with hall-effect sensors giving accuracy of 0.01A. Cool 8)
     

Share This Page