555 on-delay question

Discussion in 'The Projects Forum' started by jonot2008, Jan 17, 2014.

  1. jonot2008

    Thread Starter New Member

    Jan 17, 2014
    2
    0
    hi,

    I am working on a project which involves one these http://www.ebay.co.uk/itm/1PC-New-1...al_Components_Supplies_ET&hash=item53fbbb2362

    its based on a 555 timer, now to cut a long story short, what I need this to do is when the power is disconnected and reconnected very fast I need the timer to re-start basically I have the input in connected to both NC and NO sides of a relay in the hope that when the relay is powered (by a microswitch as a end of travel switch) it resets the time delay so waits for 10 seconds and when the relay is disconnected it does the same thing. its very hard to explain

    thanks, jonathan
     
  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    Are you saying that the ebay timer doesn't generate a complete new timing cycle if the power is turned off and then immediately turned back on?

    There are ways of making a 555 do that, but we would need to see the schematic of what is on the ebay timer board. You can easily trace it out...
     
  3. jonot2008

    Thread Starter New Member

    Jan 17, 2014
    2
    0
    yes exactly, if the power is disconnected and reconnected within milliseconds it doesn't restart it just still acts as if the cycle as finished, if you disconnected it for even a second or 2 it does restart, so basically I need it to respond very quickly, like within the click of a microswitch or relay(if that's possible?) and had a quick look for a diagram but cant find one anywhere and how do you mean trace it?
    thanks again
     
  4. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    Get a data sheet and pinout for the 555 chip. Follow the traces from each pin and see which components they go to. Note resistor values and capacitor values. Draw out a schematic
     
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