push button up / down lap counter needed

Discussion in 'The Projects Forum' started by Petrayos, Jun 10, 2014.

  1. Petrayos

    Thread Starter New Member

    Jun 10, 2014
    can anyone advise me of a circuit to achieve up / down push button lap counting to drive a multi LED display, need to count from 00 to 99 in both directions.
  2. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
    You can use a Cd4029, Cd4510,Cd40110, up/down counter, there are others.
    Last edited: Jun 10, 2014
  3. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
    And don't forget to debounce your switches!

    You'll also need two ICs to convert from BCD to 7 segment displays. (Or what do you mean by multi LED display?)
  4. ScottWang


    Aug 23, 2012
    google : two digits up / down counter schematic
    Maybe you can find one to match what need.
  5. crutschow


    Mar 14, 2008
    You could use a couple of CD40110's. It's a decade up/down counter with decoded outputs for a 7-segment display.
  6. elec_mech

    Senior Member

    Nov 12, 2008
    Welcome to AAC.


    I've done a few circuits here doing just this:

    Simple - no debounce so you could see numbers skipping. I don't recommend this, but it will help you to understand how the other circuits work.

    Ideal - with debounce, works well. May want to change R4-R6 to 100kΩ and C17-C19 with 0.1uF to further increase debouncing capability for switches with a lot of bounce.

    Extravagant - pushing up/down button once and releasing increases/decreases count by one; holding either button down will perform auto-repeat - digits will continue to advance for as long as you hold the button down. Also will flash the display and work with a remote module.

    Although now I'd use a ULN2004 in place of the UDN2981 and flip the direction of the LED's (cheaper).