555 timer problem

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

  1. cpleng7

    Thread Starter Active Member

    Dec 18, 2008
    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


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

    Here are the basic layouts...


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

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


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