two 555 timers problem

Discussion in 'The Projects Forum' started by Joakim79, Apr 7, 2011.

  1. Joakim79

    Thread Starter New Member

    Apr 7, 2011
    2
    0
    Hi All :)

    Im having difficulties finding a solution for this function, and would be happy if someone could help me in the right dirrection.

    I have two 555 timers, that are suppose to work this way:

    When T1 is triggered from a low signal, the output should remain high when trigger is low + 10sec. and open a solenoid valve. (here comes my problem) T2 should give an alarm if the solenoid valve has been open for more than 30sec. The alarm must remain low after some time, so it is not required to be reset. the circuit is to be working as normal also after the alarm.

    Hopefully someone can make sence of my descripton :)
     
    Last edited: Apr 7, 2011
  2. RFactor

    Active Member

    May 1, 2009
    33
    3
    A schematic or at least a block diagram would help.
     
  3. CDRIVE

    Senior Member

    Jul 1, 2008
    2,223
    99
    I'll second that. ;)
     
  4. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,536
    You want it to start timing on the positive transition, and also go high when the input is low? There is a different schematic for this action. It is almost a monostable, but not quite. How long do you want the alarm to stay on? What resets the T2 alarm, when the soleniod closes?
     
  5. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,536
    OK, here is what I think you are wanting to do, you tell me...

    [​IMG]
     
  6. Joakim79

    Thread Starter New Member

    Apr 7, 2011
    2
    0
    Oh, thanks :)
    I beleive this is exactly what im looking for.
    I will test it out on my test board with the rest of the circuit, and post the design once it is fuctional

    Once again thanks for the help
     
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