method to measure current

Discussion in 'General Electronics Chat' started by ranatungawk, Nov 1, 2009.

  1. ranatungawk

    Thread Starter Active Member

    Oct 30, 2008
    Is there a method to measure current of a Power Source directly ? (Ex unknown power cell ) I don’t mean the current flowing through a component …
  2. steinar96

    Active Member

    Apr 18, 2009
    Well, there is one way which is to put a small resistance (0.33 ohm perhaps) in series with the device you want to measure the current trough. You then measure the voltage drop over that device.

    The voltage will be V = IR or V = I*0.33

    Once you measure the voltage you can solve for the current.
  3. someonesdad

    Senior Member

    Jul 7, 2009
    The two common methods of measuring current that pop into my head are:

    1. Measure the corresponding voltage drop across a component that has the current through it.
    2. Measure the magnetic field associated with the current.
    Assuming method 1 is what you excluded, you're left with measuring the magnetic field of the current. There are a number of tools out there that use this method for both AC and DC measurements (clamp-on ammeters) made by e.g. F.W. Bell, Fluke, etc. The HP 428B is a good tool and can still be occasionally found on ebay. You can also find web sites that instruct you in how to make your own Hall effect sensor for e.g. measuring DC currents under the hood of an auto.
  4. ranatungawk

    Thread Starter Active Member

    Oct 30, 2008
    Thanks 4 the excellent advice !!!!