CD4017 RESET and CLOCK ENABLE SEQUENCE

Discussion in 'The Projects Forum' started by jhatch200, Apr 28, 2012.

  1. jhatch200

    Thread Starter New Member

    Apr 28, 2012
    1
    0
    Hello, (Newbie here)
    I've been going over the various threads on the CD4017 Counter IC and have a question regarding the proper way to RESET and ENABLE. What I want to do is count from 1 to 5 seconds (I don't really need to go to 10 seconds - yet) and have the output control a gate on some CD4033 Counter LED driver ICs. I have tested the CD4033 ICs and that part of the circuit works fine. Now the rub - I don't get repeatable times with the CD4017 circuit. Please see attachment. I'm probably doing something stupid - but hopefully someone can help out a bit. I think it may have to do with the timing of the circuit, though I'm not sure.
    Thank you, J
     
  2. #12

    Expert

    Nov 30, 2010
    16,284
    6,797
    Your enable circuit has no connection to the reset function.
    If you don't reset, how can you expect consistent counts?
     
  3. MrChips

    Moderator

    Oct 2, 2009
    12,441
    3,361
    There are two things wrong with the way both the RESET and START circuits are wired.

    Pin-2 and Pin-9 of the CD4001 Dual Input NOR gate are driven by capacitors.
    This is not correct. You need some kind of DC bias voltage for the CMOS gate to function properly.

    Pin-1 and Pin-8 inputs are both set to logic HIGH via 10k pullup resistors. These would make the outputs at pin-3 and pin-10 of the NOR gate permanently LOW. There will be no change at the outputs of these two gates.
     
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