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LED ammeter circuit

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Discussion in 'LEDs and Optoelectronics' started by vinod chandran, Nov 17, 2012.

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  1. Nov 17, 2012 #1
    vinod chandran

    vinod chandran

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    Jun 21, 2011
    Hi all,
    Is it possible to make a LED ammeter ?. Like the LM3914 voltmeter, this ammeter should have some LEDs and first LED will glow when the load consume 50mA. And the second will glow for 100mA, third led for 200mA. and so on. Does anybody have a circuit for this?.
     
  2. Nov 17, 2012 #2
    davenn

    davenn Moderator

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    I havent seen it done
    used as a Voltmeter ... yes, so measuring the Voltage drop across a shunt resistance that the current would be flowing through would probably be the way to go :)

    Dave
     
    Last edited: Nov 18, 2012
  3. Nov 18, 2012 #3
    (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    What Dave said.

    Typically you' might use an op-amp to amplify the voltage across a shunt resistor and feed that to the input of a 3914.
     
  4. Nov 18, 2012 #4
    vinod chandran

    vinod chandran

    192
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    Jun 21, 2011
    Hi,
    Thank you davenn and steve. Could you please draw me a circuit of your idea?.
     
  5. Nov 18, 2012 #5
    davenn

    davenn Moderator

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    have you looked at the datasheet for the chip there are lots of various examples there?, sure to be one that only needs slight modification

    Dave
     
    Last edited: Nov 20, 2012
  6. Nov 20, 2012 #6
    gorgon

    gorgon

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    Jun 6, 2011
    You could use the ina139 to monitor the current and then the 3914 to display it.
     
  7. Nov 23, 2012 #7
    vinod chandran

    vinod chandran

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    Jun 21, 2011
    Hi gorgon Thank you. Let me try.
     
  8. Nov 23, 2012 #8
    vinod chandran

    vinod chandran

    192
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    Jun 21, 2011
    Hi davenn,
    Yes i do. Let me try. Thanks.
     
  9. Nov 30, 2013 #9
    benneally

    benneally

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    Nov 30, 2013
    Hello,

    I was just wondering if you managed to acheive this? I am also looking to make a simple 'visual' ammeter by using a scale of LEDs.

    I would be very keen to hear of your efforts!

    Cheers

    Ben
     
  10. Dec 1, 2013 #10
    (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    You could have a look at something like this. The device I have linked to generates a voltage which varies by 185mV per amp.

    This voltage is generated without a significant series resistance, so there is a far lower voltage drop. You can use thi voltage (possibly amplified using an op-amp) to be the input of something like an LM3914 (or you could use a microcontroller) and produce the display you require.
     
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