LED with AND gate intput

Discussion in 'General Electronics Chat' started by Dritech, Jun 21, 2014.

  1. Dritech

    Thread Starter Well-Known Member

    Sep 21, 2011
    756
    5
    Hi all,

    I want to connector a limiter switch (NC) with an AND gate IC input. With the same input I also need to connect an LED to turn on when the limit switch is reached (open contacts).

    How can I achieve this please?

    I did the circuit attached but the input is going to float since there is both 5V from the LED and ground from the pull down resistor.
     
  2. ScottWang

    Moderator

    Aug 23, 2012
    4,858
    767
    The attached circuit is a easy way, but it will spend more current , and it is according to the R1.

    [​IMG]
     
  3. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,813
    1,105
    When the NC limit switch opens do you want the AND gate input to go high or low?
     
  4. Dritech

    Thread Starter Well-Known Member

    Sep 21, 2011
    756
    5
    Thanks for the replies.

    I want the input of the AND gate to go low when the NC limit switch is reached.

    Is is ok to connect the LED as attached? Will the resistor act as a pull down resistor or will the input remain floating?

    I worked on simulation, but sometimes I do not fully trust a simulator.

    Edit: The link below is the schematic. Sorry I did not uploaded here because it is not loading.

    http://we.tl/gfJRLDbbcB
     
    Last edited: Jun 21, 2014
  5. Dritech

    Thread Starter Well-Known Member

    Sep 21, 2011
    756
    5
    Hi,

    I was referring to the schematic in the link below (please press the download button for the schematic):

    http://we.tl/gfJRLDbbcB
     
  6. ScottWang

    Moderator

    Aug 23, 2012
    4,858
    767
    I just thought, is that your are wrong or mine, and think over maybe that is my fault, because I thought the NC in another way.

    Please check the logic, is that suit for your need?

    [​IMG]
     
    Dritech likes this.
  7. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,813
    1,105
    You can post your schematic here. Click 'Go Advanced', then scroll down, then click 'Manage Attachments'.

    Edit:
    How about this?
     
    Last edited: Jun 21, 2014
    Dritech likes this.
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