LM3914 + Current Sensor

Discussion in 'The Projects Forum' started by Pencil, Jul 11, 2010.

  1. Pencil

    Thread Starter Active Member

    Dec 8, 2009
    Hello everyone,

    I have tried to design a circuit to monitor
    current (DC) in a wire using a Honeywell CSLA2CD
    sensor and an LM3914. I would appreciate the effort
    if I could get some advice/critique on my work so far.
    I have attached the schematic and relevant datasheets
    for convenience. My notes are included with the drawing.

    Thanks for looking.

    P.S. Automotive application is mentioned in "Notes" section.
    I am aware of the recent "discussion" regarding these
    types of circuits and feel it is appropriate. (It is non-
    invasive, does not penetrate any bulkheads, and will
    not alter any system functions).
  2. hgmjr


    Jan 28, 2005
    Can you provide a brief detailed description of what you are trying to do with the circuit beyond the fact that you are looking to monitor the current? What are the various limits you are looking for in terms of amps in the line being monitored?

    Last edited: Jul 11, 2010
  3. windoze killa

    AAC Fanatic!

    Feb 23, 2006
    To me it looks like a digital bar graph current meter/indicator. First glance it seems to look ok to me.
  4. Pencil

    Thread Starter Active Member

    Dec 8, 2009
    Brief description: Mostly just building for fun/practice/learning. As far
    as the automotive concerns, I have an old truck (1972) I am always
    working on and thought I'd add a little current monitor to the 2-speed
    axle (electric) to give an indication if it ever "hung-up" when shifting.
    I wanted to do this in the least invasive way, hence using a sensor
    that I wouldn't have to insert anything to the line. I mentioned the auto-
    motive aspect as a "full-disclosure" kind of statement, if it don't work
    for its intended purpose I'll change it up, run it off some rechargeable
    batteries and play with it somewhere else.

    Various limits:
    Supply voltage: 12.5-16V
    Monitored Load : 0-16A (this may need adjusted based on future findings)
    Load for full scale: 15.3A (see above)
    1st LED lights @ 0A
    I haven't checked the exact current requirements as of yet, but I do know
    that the circuit is running on a 20A fuse.

    Thanks for responding. I hope this is acceptable.