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"CD-player type" pushbutton control

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by Jimbo, Aug 8, 2003.

  1. Jimbo

    Jimbo New Member

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    Hello all,

    for one of my designs, I wanted to create the type of button that is found on just about every piece of electronic equipment today, for example the CD-track selection button on CD players (hence the message title, as I don't know the "offical" name of such a switch).

    It works as follows: push and immediately release the button, you get one output pulse (and the CD-track number is incremented by one). Push and hold the button for about a second, and you get a pulse train (and the CD-track numbers increments automatically).

    What I've made up to now is a button which simultaniously drives a monostable and an astable vibrator (actually using 2 555ers as I had heaps lying around). The 'start' of the astable vibrator is delayed by a relatively huge RC-network to get my one-second delay (with an LM324 as comparator to trigger the start). The outputs of both vibrators are then simply joined trough diodes.

    I felt this solution was wasting components (even if I replace the 555ers with transistor-based vibrators, I still need two vibrators), so I wanted something better.

    Second idea (which was never created) was to simply drive one astable vibrator with the switch, but that gives the 'time-base' problem: the frequency of this vibrator will never be faster than the 'hold'-time, because the RC values never change. In effect: the delay after the first pulse will be exactly the same as the delay after all other pulses, but that is not what I want. The pulse train needs to speed up after hold, or in (an attempt at) wave forms:

    Code (text):


    ..........__________________________________________
    button:___|                                         |____________
    ..........._            _     _     _     _ _
    output: __| |__________| |___| |___| |___| |___| |________________

     
    So basically I am stuck. How would you lot go about designing a "CD-player button"?[/code]
     
  2. Sebi

    Sebi New Member

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    Here is a sematic, the output same as You drawed.
     

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  3. Roff

    Roff Well-Known Member

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    Here's a way you can use a 555, if you don't mind that the first pulse stays high for a long time, like this:
     

    Attached Files:

  4. dave

    Dave New Member

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  5. Jimbo

    Jimbo New Member

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    Cool, thx guys!

    (been away from the net for a week)
     
  6. The Real MicroMan

    The Real MicroMan New Member

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    learn to program a microcontroller. you can do what you described with a switch a resistor and one micro.
     
  7. nettron1000

    nettron1000 New Member

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    Wouldnt a dedicated microcontroller be a bit of overkill for this rather simple application ?
     

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