Power off Delay circuits

Discussion in 'The Projects Forum' started by nachie, Jun 21, 2010.

  1. nachie

    Thread Starter New Member

    Jun 21, 2010
    3
    0
    Hi,
    I am no electronics guy. I am building a solenoid operated latch which I would like to keep open for 10-12 secs after the push button switch is pressed. The circuit needs to be operated at 12v DC. After the trigger is given, circuit should deliver 12v to the load for about 10 secs, and then cut off the load till the next time the trigger is given. The trigger has to be manual everytime.

    Can some of you here give me some pointers on how this can be done? I would really appreciate any kind of information provided here.
    [​IMG]
     
  2. nachie

    Thread Starter New Member

    Jun 21, 2010
    3
    0

    Here, the 'latch' is a door latch and not latch in electronic terms. :)
     
  3. retched

    AAC Fanatic!

    Dec 5, 2009
    5,201
    312
    Sure. A pulse generator, or one-shot monostable, that produces a 10sec pulse at 12vDC will do the trick.

    Something like this:
    [​IMG]

    With R1 as 10k ohms and C1 as 1000uF will give you a ~11 seconds pulse.

    The button should be a 'momentary' or press and release type.

    Depending on the current you require for the solenoid, will determine the transistor or fet you use with this to pass the current to the solenoid.
     
  4. nachie

    Thread Starter New Member

    Jun 21, 2010
    3
    0
    Hi,
    Thanks for letting me in on this one. I'll try it out.. btw, I also tried using some other circuits, but they dint work out. Could you determine if they were correct.. not required, but just out of curiosity..
    [​IMG]
    In this the IC is heating up, and nothing else is happening.

    [​IMG]
    In this one, the relay remains off constantly, weather switch is on or off..


    Meanwhile I'll try out this circuit, and post the results :)

    Thanks
     
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