LED Bargraph LM3914 question

Discussion in 'The Projects Forum' started by madriaanse, Apr 27, 2011.

  1. madriaanse

    Thread Starter New Member

    Mar 14, 2010
    7
    0
    Dear SgtWookie,

    I found your posting on the forum regarding the use of an LM3914 to drive an LED bargraph:
    Quote:
    Originally Posted by SgtWookie [​IMG]
    Attached is a schematic of a 0v to 5v 10-LED Bar Graph voltmeter made using a National Semiconducor LM3914 IC and a 10-segment LED bar display, with a couple of resistors and a capacitor.

    To change it to read from 0v to 6v, replace R2 with a 4.6k resistor. That's it.

    You can power the circuit with a 9v transistor battery.

    It does not get a whole lot more simple than this to build a 10-segment voltmeter display at home.

    The schematic came from page 2 of National's datasheet.
    The datasheet is available from this page:
    http://www.national.com/mpf/LM/LM3914.html
    Direct link to datasheet:
    http://www.national.com/ds.cgi/LM/LM3914.pdf
    Jameco supposedly carries the LM3914N-1/NOPB for around $1.55, but their server is down at the moment.
    Jameco does not have a minimum order like many suppliers do.


    However, I am needing to adapt the above referenced circuit to monitor between 11.3 - 13.1 volts. To Clarify, 13.1V -> all LED's ON. 11.3V -> 1 LED ON. Below 11.3V -> all LED's OFF. Is it possible to do this with the LM3914? Power would come from the same 12V battery. And if so, what adaptations would be required to the circuit you linked to:http://www.national.com/images/pf/LM3914/00797001.pdf?

    Thank you!!

    M.
     
  2. SgtWookie

    Expert

    Jul 17, 2007
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    Last edited: Apr 27, 2011
  3. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    201
    Actually the TRUE factory data sheet has all the info on making expanded scale meters with starting voltages other than 0V with the IC. It takes a bit of math but what doesn't?
     
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