variable timer astable to monostable

Discussion in 'The Projects Forum' started by briian d, Feb 2, 2013.

  1. briian d

    Thread Starter New Member

    Jan 12, 2012
    3
    0
    hi please excuse my lack of understanding i am trying to build a 555 timer which varies on time from 0.5 secs to 2 secs the off time to be about 25% of on time or 75% duty cycle. ( i have this working ok now )

    i am struggling with the next bit ( to say the least ). i want a monostable timer to give as near as i can double the off time of first circuit . i hope i have made that clear ie if first time is off for 0.5 secs then 2nd timer to give a oneshot 1.0 second on time pulse again that is variable ( controlled by first circuit )

    first post on here ( i get lost in the maths, but i can follow some circuits until i get to the 3rd or fourth component then forget what happened ) please be gentle. btw this is a great forum for learning .

    best regards:)
     
  2. MrChips

    Moderator

    Oct 2, 2009
    12,446
    3,362
    What you are attempting to do is not easy with 555 timers.
    You can do this with a single microcontroller chip.
     
  3. briian d

    Thread Starter New Member

    Jan 12, 2012
    3
    0
    hi mrchips thanks very much for reply, could i have a clue please what sort of microcontroller ? ( this is looking like it will be above my pay grade )


    regards
     
  4. MrChips

    Moderator

    Oct 2, 2009
    12,446
    3,362
    Just about any mcu will do the trick.
    Begin by drawing a timing diagram of what you hope to accomplish.
     
  5. briian d

    Thread Starter New Member

    Jan 12, 2012
    3
    0
    hi thanks for replys I will go down the switched resister array & adjust it to suit timing required.

    best regards
     
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