How to make a 59-0 down counter?

Discussion in 'The Projects Forum' started by lildawg, Jul 16, 2009.

  1. lildawg

    Thread Starter New Member

    May 28, 2009
    3
    0
    I found this schematic to make an up-down counter.. however all I need is a down counter starting from 59-0.. I've been staring at this circuit for hours but still havent figured out a way to simplify this circuit. Is there any way I can do it? thanks


    http://members.shaw.ca/roma/up-down.gif
     
  2. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    Connect a 10K resistor between the emitter of the transistor and ground.
     
  3. lildawg

    Thread Starter New Member

    May 28, 2009
    3
    0
    what is the function of the resistor at the emitter of the transistor? as a pull down resistor?
     
  4. millwood

    Guest

    a lowly pic12f675 will count down any number you want.
     
  5. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    Yes, it pulls the input of the counter to 0V when the transistor is off. Without it the input will 'float'. A TTL chip would read a floating input as high but a MOS chip would have an unknown logic state.
     
  6. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
    1,758
    98
    Alberto it might be helpful if you also attached the source code.
     
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