Please help with this counter schematic

Discussion in 'The Projects Forum' started by dyeraaron, Oct 16, 2009.

  1. dyeraaron

    Thread Starter Active Member

    Oct 27, 2008
    57
    0
    Hey guys, I'm beating my head against the wall and probing every point to try to figure out why my counter won't count..it just stays at 0...heres the schematic

    [​IMG]
     
  2. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,535
    OK, here is the datasheet.

    http://focus.ti.com/lit/ds/symlink/sn74192.pdf

    I'm looking at page 11 to see if it applies.

    Before I connected the BCD decoder I'd use some LED circuits to see the count. A variation off this.

    [​IMG]

    Also, get rid of the 555, and ground those sides of the switches. At this point you don't care about debounce, you just want a count signal.
     
    Last edited: Oct 16, 2009
  3. bundick

    Active Member

    Dec 19, 2007
    97
    1
    I'd first look at the output of the 555 to see if your clock is ticking.
    Then I'd look at the outputs of "92" looking for changing states.
    Do you have that?
     
  4. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,535
    Yeah, I was thinking maybe an LED on the 555 too, after we verified the count function was working.
     
  5. dyeraaron

    Thread Starter Active Member

    Oct 27, 2008
    57
    0
    Bill,

    I was looking at pg. 11 like you mentioned and comparing it to the schematic......Pin 14 of the 74192 is coming off of the reset button tied to high.....in the pg. 11 diagram pin 14 or CLR is grounded. So i guess I'll be able to count up or down but can't reset it???? Load is pin 11 Which I have tied to High but how can I reset the circuit?
     
  6. dyeraaron

    Thread Starter Active Member

    Oct 27, 2008
    57
    0
    This maybe a dumb question and its why I hate messing with stupid 555's but is pin 2 jumpered to pin 6 or are they both tied to high...and is pin 7 jumpered to pin 2 by the resistor or is pin 2 using the resistor as a pull up to high?
     
  7. dyeraaron

    Thread Starter Active Member

    Oct 27, 2008
    57
    0
    on the 74192...the pins 4 and 5 for up and down count have pull up resistors tied to high.....if I take the 555 out of the circuitry, and ground the switches like we mentioned wouldn't this short out the circuit?
     
  8. JoeJester

    AAC Fanatic!

    Apr 26, 2005
    3,373
    1,157
    Here's a simulation of your diagram.

    The swf shows the up and down count and reset funtions. It includes the recommendations of the LEDs to show the '192 working and the '555 working.

    http://www.tech-service.net/joe/up-dn_counter_swf.asp

    An open source screen capture did the recording.

    on edit: changed extension to .asp
     
    Last edited: Oct 26, 2009
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