555 timer/7 segment display/1 second intervals

Discussion in 'Homework Help' started by fitzyafcb, Feb 20, 2016.

  1. fitzyafcb

    Thread Starter New Member

    Feb 20, 2016
    4
    0
    Hi I could really do with some help please.

    I am a first year part time HNC student with very little experience in electronics and using Proteus, but i'm getting by so far.

    My next assignment task is to apply a 555 timer to my working 16 character word circuit displayed on the 7 segment display. The timer needs to run the display at 1 second intervals. I am fairly confident with my resistor/capacitor values to achieve this, but I just can't get it right to display each of the 16 character letters. It's currently shows only the last letter!. What have I done wrong? What's missing? Any help would be much appreciated. thanks in advance.

    upload_2016-2-20_13-18-15.png
    upload_2016-2-20_13-18-42.png
     
  2. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
    5,005
    745
    Pins 2,6 of the 555 needs to be connected to R2,C1 junction.
     
  3. fitzyafcb

    Thread Starter New Member

    Feb 20, 2016
    4
    0
    Thanks for your reply but I have tried what you have suggested and it still doesn't seem to work. I can get the first and last characters to display now but not the rest
     
  4. bertus

    Administrator

    Apr 5, 2008
    15,652
    2,348
    Hello,

    Should there be a counter that goes through the 16 numbers?
    Now A through D can only be 0 or 1 dependend on the 555 state and will all have the same value.

    Bertus
     
  5. fitzyafcb

    Thread Starter New Member

    Feb 20, 2016
    4
    0
    of course thanks. perhaps a 4026 counter will work i will give it a try
     
  6. dannyf

    Well-Known Member

    Sep 13, 2015
    1,836
    367
    Because that's how it is designed to work - it only has two states.

    For it to display 16 states, you will need a counter that counts to 16 distinct states.
     
  7. fitzyafcb

    Thread Starter New Member

    Feb 20, 2016
    4
    0
    ah yes finally i've cracked it!!! i think
    i've used a 4-input JK flip flop ( i think that's what it's called!!) lmao
    It all looks good to me, all the characters are displaying.
    wow that feels good!

    many thanks
     
Loading...