555 timer problem

Discussion in 'Homework Help' started by cpleng7, Mar 28, 2009.

  1. cpleng7

    Thread Starter Active Member

    Dec 18, 2008
    120
    0
    i have to design a astable mutivibrator , the duty cycle of this design is 16% and the frequency is 24Khz.

    May I know what type of diode I should choose in order to get the duty cycle and frequency to be same.

    I Have try a few type of diode i find out that each diode have difference duty cycle and frequency.

    May I know how to choose the suitable diode. Thank you
     
  2. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536
    A 555 doesn't use a diode for astable mode.

    Here are the basic layouts...

    [​IMG]

    You can use an invertor to get the required duty cycle.

    The other way to do this is like this...

    [​IMG]

    The diodes aren't important, it is the ratio of R that does it.
     
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