logic problem? please help

Discussion in 'General Electronics Chat' started by llinocoe, Feb 28, 2009.

  1. llinocoe

    Thread Starter Member

    Sep 30, 2008
    10
    0
    How can be a BCD counter always start to zero whenever we use....?

    we're working on a scoring system starting at 0 using a bcd counter and a 4bit full adder that needs to start from 0 every start of the game

    so what must be the design in order that a bcd counter always start at 0?
     
  2. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    There is a "MR" or Master Reset pin that will reset the counter to zero. Check the data sheet for the particular IC you are using.
     
  3. NavjeetSingh

    New Member

    Feb 8, 2009
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    Master Reset is an inbuilt option. You can also set an external circuit linked to 'clear' pin that will also do the job.
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
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    Some have a parallel load function that can reset the count to zero.
     
  5. mik3

    Senior Member

    Feb 4, 2008
    4,846
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    Post the circuit you designed up to now to see it and tell you.
     
  6. llinocoe

    Thread Starter Member

    Sep 30, 2008
    10
    0
    I'm using 7493 IC which had 2 reset pins and it indeed count 0 to 9 binary numbers in a bcd counter . but were after on how to make it always start to 0 whenever we apply voltage. I'm thinkin that it couldn't be possible for a bcd counter to always start to zero alone by only changing its pin connection but you told about a set of external circuit. can you show what it will be and i'll try if it works...thanks a lot in advance
     
  7. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Connect both of the reset pins together.
    Connect a 1uF capacitor from the reset pins to Vcc.
    Connect a 10k resistor from the reset pins to ground.

    When power is applied, the capacitor will momentarily pull the reset pins high, and then the capacitor will charge to Vcc through the 10k resistor, causing the reset pins to fall to 0v, and enabling the IC to count.
    [eta]
    When power is removed from the circuit, the capacitor will discharge through the 10k resistor.
     
    Last edited: Mar 1, 2009
  8. italo

    New Member

    Nov 20, 2005
    205
    1
    When you apply voltage the state of any counter is where? How can you define the start easy. Add an AND gate with a big cap to the input and a power UP resistor this guardees a reset from 0 to one determine by the rc time constant and tresh hold of the gate. Need the a one instead use a NAND gate.
     
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