Monostable -> Astable -> 4017

Discussion in 'General Electronics Chat' started by edwardholmes91, May 22, 2013.

  1. edwardholmes91

    Thread Starter Member

    Feb 25, 2013
    186
    19
    Hey Everyone,

    Just a really quick question. I am making an electronic dice and I originally had an astable at 5kHz going into a 4017 that cycles through 1 - 6. When you let go your dice lands on a number.

    I wanted to extend it so that when you press and it will cycle at a slower speed for a set adjustable amount of time. I therefore added a monostable into the mix and it works great.

    The only problem is that the circuit now goes for a set amount of time regardless of how long you press the buttons. Is there a way of making the circuit cycle when the button is pressed and then continue for an amount of time?

    Probably a really stupid question, but worth asking a figures before I actually etched the board.
     
  2. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
    5,005
    745
    Yes put an electrolytic capacitor across the push switch say 10uF and add a 100K preset in series with the 1K resistor (R6) on the Enable pin, that should give you a time delay of upto 10seconds.
     
    Last edited: May 22, 2013
  3. Ron H

    AAC Fanatic!

    Apr 14, 2005
    7,050
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    Attached is one way to do extend the duration of your switch signal.
    Use your 555 oscillator as on your schematic. Add the additional circuitry in the attachment to your switch. It consists of a resistor and a capacitor.
    The 4017 will count as long as the button is pressed, and for a while afterward. The extra time is determined by R1 and C1.
     
    Last edited: May 22, 2013
  4. edwardholmes91

    Thread Starter Member

    Feb 25, 2013
    186
    19
    What I'm looking for is to get the counter to sequence as it is while the button is pressed and then when it's released start the monostable if that makes sense? At the moment it only cycles for the amount of time on the monostable regardless of how long you press and hold a button.
     
  5. LDC3

    Active Member

    Apr 27, 2013
    920
    160
    You will want to connect the switch to the RC circuit to either charge it or to discharge it, so when you release the switch the 555 will be on until the RC turns it off.
    BTW, remember to debounce the switch.
     
  6. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    Dodgy Dave is right. You don't need the CD40106. I'm editing my previous post.
     
  7. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    Are you comfortable with the fact that you don't need a monostable?
     
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