Voltage Level Detection in 4 Distinct Steps

Discussion in 'The Projects Forum' started by MtheInventor, Jul 31, 2009.

  1. MtheInventor

    Thread Starter New Member

    Jul 31, 2009
    2
    0
    Gents,

    I looking at the LM3914 or a Quad Op Amp for the following result from a single analog line:
    9V = turn on PNP FET or BJGT to short DC motor terminals

    10V = turn on PNP FET or BJGT to short DC motor terminals, Turn off 2 of 4 in Series LED (came on at 5 volts),

    12V = Funcs of 9V, 10V off, Turn on NCh Fet for DC motor

    14V = Funcs of 9V, 10V off, Turn on NCh Fet for DC motor, Turn on 4 of 4 LEDs at lower current/brightness

    =============
    The steps can be modified if needed. I like the idea of using the "dot mode" in the LM3914 for built in auto turn off of functions, but am concerned whether I have control over the steps/range (get 1-2 volt per step?).

    I can go with the OpAmp, but have to do all the turn off stuff manually which is doable.

    I want low part count, simple analog function, which method do you guys recommend? Know of projects like this? I searched the forum, but did not see an answer.

    Sincere thanks,

    MTI
     
  2. jj_alukkas

    Well-Known Member

    Jan 8, 2009
    751
    5
    Use the LM3914 in dot mode and drive each device with transistors. Simple and easy.
     
  3. MtheInventor

    Thread Starter New Member

    Jul 31, 2009
    2
    0
    You could well be right. Any idea where a SPICE model for it would be? National did not seem to anxious to create one. Or is it just too obvious?
     
Loading...