Lm339 Voltage LED indicator (S.0.S)

Discussion in 'General Electronics Chat' started by shorabkareem, Jun 19, 2012.

  1. shorabkareem

    Thread Starter New Member

    Jan 19, 2012
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    Can anybody please help me. I need to have a wiring Schematic as how i can build a LM339 voltage indicator with LED as indicators

    to connect to my Lm317 voltage regulator circuit (out put from 1.25 V to 30 V) which i have already built.

    I am complete beginner to electronics therefore, please explain to me in very simple electronic terms with clear guidelines.

    * will appreciate if you can show me as how i can connect one or two more LM339 IC if i want to increase the LEDs.

    tks : sdk
     
  2. praondevou

    AAC Fanatic!

    Jul 9, 2011
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    The maximum output current is specified for 20mA so it is maybe good for 1 or two LEDs. If you want to use more you need a buffer (simple transistor stage).

    You didn't say at what voltages it should indicate something. What condition do you want to indicate? Overvoltage undervoltage? What hysteresis, if any?
     
  3. #12

    Expert

    Nov 30, 2010
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    You might want to look at this chip.
     
  4. shortbus

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    Sep 30, 2009
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  5. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    3.1 pages is over-kill; how about Forrest Mims III's Bargraph. If top of R2 is set to 4 V, then each step will be one V
     
  6. shorabkareem

    Thread Starter New Member

    Jan 19, 2012
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    Thank you for you quick response

    But please note i need to have wiring diagram as which + & - wires goes to the 339 ic (supply and Ground) and which wires goes to the voltage input from my 317 voltage regulator. can i use one supply (battery) to power the whole Ic
     
  7. shorabkareem

    Thread Starter New Member

    Jan 19, 2012
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    I need the LEDs to blink (ON) to indicate voltage in sequential order 6 V, 12v, 20v and 24v etc.
     
  8. Bernard

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    Aug 7, 2008
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    If input is 7V, would a LED indicating 6V to 12V be acceptable, or just 6V +- 1/4V. How many steps?
     
  9. shorabkareem

    Thread Starter New Member

    Jan 19, 2012
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    i don't mind the voltage sequence but i need the LED to indicate in 04 step or more to show there were voltage increment.

    how much supply voltage do i have to used for the 339 ic?

    my input voltage is from 1.25 v to about 30 v
     
  10. #12

    Expert

    Nov 30, 2010
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    This datasheet tells what the LM339 chip needs to operate properly.
     
  11. Bernard

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    Aug 7, 2008
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    In a bar graph display when reading top V, all LEDs are on, not great for battery operation if on for long time periods. A 5 or 6V regulated wall wart is a possibility. No labled schematic is possible without knowing number of steps & V assigned to each step. It is easier if all steps are uniform, but not required -- just makes a verry messey V divider.
     
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