low battery indicator

Discussion in 'General Electronics Chat' started by aimaldaudkhan, Feb 5, 2014.

  1. aimaldaudkhan

    Thread Starter Member

    Jan 25, 2013
    38
    0
    hello all
    i want to know that how i connect a zener to the battery for voltage indocator my battery is 6 v and 4.5AH????
    and how i calculate the zener diode ???
     
  2. crutschow

    Expert

    Mar 14, 2008
    13,000
    3,229
    What is the exact voltage you want to indicate?

    A zener alone will likely not work. A zener along with a comparator driving an LED would be much better.
     
  3. aimaldaudkhan

    Thread Starter Member

    Jan 25, 2013
    38
    0

    i will also connect a led with zener but dont know the calculation
     
  4. ian field

    Distinguished Member

    Oct 27, 2012
    4,413
    782
    Some of the TL431 datasheets have application examples of both low & high voltage indicators,

    There seems to be 2 camps of manufacturers who duplicate each others applications, so search for a collection of TL431 datasheets and review the apps in all of them.
     
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  5. crutschow

    Expert

    Mar 14, 2008
    13,000
    3,229
    Zeners come in fixed voltages with a tolerance. You just pick the one with the closest voltage to that which you want and connect the zener, a suitable resistor, and the LED in series between the power and ground.

    Note that this will light the LED when the voltage is high with the LED turning off when the voltage drops below the combined voltage of the Zener and LED in series.
     
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