16 Bit Gray Code Encoder Circuit Problem

Discussion in 'General Electronics Chat' started by waynehamradio, Feb 11, 2011.

  1. waynehamradio

    Thread Starter New Member

    May 26, 2005
    Hello everyone; This is my first post.

    I built a 16 bit, 4 concentric circle Gray Code Wheel, with Infrared emitters and detectors to read the Gray Code to drive 16 small LEDs arranged to indicate every 22.5 degrees of a compass circle. The object of this device is to indicate the direction of a remotely located direction finding loop antenna.

    The Gray Code wheel encodes properly in sequence with one exception. When it is rotating clockwise with the loop , the indicating LEDs are going in the opposite direction. Same for counter clockwise rotation of the code wheel, as the LEDs go in the opposite direction as the loop.

    Electronically, the whole system is done with hardware, no PC or software involved, with the code wheel segments being "read" by the IR phototransistors which feed a non-inverting LM339 comparitor. The comparator feeds a 7486 Gray Code to Binary converter which feeds a 74154 demultiplexer to light the proper LEDs in sequence.

    I can't find a solution to get the LED sequence indicating the same direction as the actual loop rotation.

    Appreciate any and all suggestions, corrections etc.
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    We need the pattern on the wheel and a schematic to tell what's going on.
  3. beenthere

    Retired Moderator

    Apr 20, 2004
    To the OP: These are public forums. It is against the spirit of the public nature of the question and answers to make them in private.

    To the email question:
    I can't reply because there is no schematic to examine.
  4. BillB3857

    AAC Fanatic!

    Feb 28, 2009
    Turn the wheel over.