Can't find the current?... :/

Discussion in 'General Electronics Chat' started by Captain E, Jun 19, 2015.

  1. Captain E

    Thread Starter Member

    Jun 16, 2015
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    6
    Hi!
    Some trouble ahead...

    I'm using the Arduino UNO with 5V as the Voltage source, so I know the TOTAL voltage.
    I need the TOTAL current to move on and as I dont have any resistors attached yet, so I can't calculate the TOTAL current of my circuit.

    Very new I am indeed, and in my "math practice" in electronics I always got the resistance(*) in the entire circuit in the exercise instructions. Now I dont.
    So how can I find the total current for the Arduino UNO?

    Maybe the way I'm doing this is bad? Please tell me, if so :)

    Thanks! Stay awesome.

    *EDITED from Voltage to resistance. remembered incorrectly x)
     
  2. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
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  3. Captain E

    Thread Starter Member

    Jun 16, 2015
    81
    6
    Thanks for your help but I'm afraid im still lost.. Want to be sure about this so nothing gest broken :p

    It says 46.5 mAmps using a USB cable from the first search result from you, so is this value the same for every UNO when using 5V from a USB cable?
    Can it change, when always using the same Voltage, 5V?
     
  4. DickCappels

    Moderator

    Aug 21, 2008
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    Not necessarily. For example, if you change the clock prescaler you will cause a significant change in current.

    By the way, I think there is a good chance that each of us sees different search results from Google based on our search histories.
     
  5. Captain E

    Thread Starter Member

    Jun 16, 2015
    81
    6
    Thanks for the reply, but I dont have any access for that right now :/ (we're moving and everything organized in boxes, so no touchy)

    (Moderator note: I hope you don't mind that I cleaned things up.)
     
    Last edited by a moderator: Jun 19, 2015
  6. DickCappels

    Moderator

    Aug 21, 2008
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    Which search result did you take you to your answer (what is the URL)?
     
  7. Captain E

    Thread Starter Member

    Jun 16, 2015
    81
    6
    Haha oh ^^
    Here I got the 46.5 result: http://gadgetmakersblog.com/arduino-power-consumption/
     
  8. DickCappels

    Moderator

    Aug 21, 2008
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    Note that 46.5 ma was when running at 16 MHz.
     
  9. Captain E

    Thread Starter Member

    Jun 16, 2015
    81
    6
    Yes, I got that :D Thanks again :))
     
  10. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
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    Captain,

    Your question is like asking "I have a 12V car, how much current (how big a battery) do I need to power it?"

    Let's see. If it is parked, with the key off, a tiny bit...
    If the radio is on, but still parked, a bit more...
    If the headlights and radio is on, but still parked, quite a lot...
    While cranking the starter, a huge amount (100s of Amps)
    If driving, almost nothing, because the alternator picks up the load...

    Similar with the Arduino. The question should be " what is the worst case power draw if the Arduino is doing something useful, and it is not plugged into the USB (like the car's alternator)"?
     
  11. wmodavis

    Well-Known Member

    Oct 23, 2010
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    Try measuring it with an ammeter. Every experimenter/learner or what ever you call yourself needs one.
     
  12. Captain E

    Thread Starter Member

    Jun 16, 2015
    81
    6
    Ooh I see :D Thanks a lot, Mike :D
     
  13. Captain E

    Thread Starter Member

    Jun 16, 2015
    81
    6
    Yea I now get that I really need that.. OF TO THE STORE I GO. (tomorrow, I'm lazy..) xD

    Thanks!
     
  14. #12

    Expert

    Nov 30, 2010
    16,345
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    Just a tip...a cheap meter will do for beginners. You can often find one in the range of $10 or less if you know where to look. (Does Harbor Freight exist in Sweden?)
     
  15. Captain E

    Thread Starter Member

    Jun 16, 2015
    81
    6
    Nope, but I know a few nearby places with the things I need, so it's just a matter of time :3
     
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