How to setup the values of R1, R2 to hold a high output 30 seconds for a 555 monostable?

Discussion in 'General Electronics Chat' started by boatsman, Oct 14, 2015.

  1. boatsman

    Thread Starter Senior Member

    Jan 17, 2008
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  2. wayneh

    Expert

    Sep 9, 2010
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    I see two circuits in that older thread. Which one are we talking about here?

    You could increase C1 or one of the timing resistors.
     
  3. dl324

    Distinguished Member

    Mar 30, 2015
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    30 seconds is a long time for a 555 timer if you need it to be accurate, but you can use this graph:
    555delayGraph.jpg
     
  4. AnalogKid

    Distinguished Member

    Aug 1, 2013
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  5. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    The capacitor needs to have a very low leakage to achieve a delay time that long.
     
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