Timer Delay

Discussion in 'The Projects Forum' started by tornado151, Apr 20, 2010.

  1. tornado151

    Thread Starter Member

    Apr 15, 2010
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    Hi,
    Is there a really simple module or circuit that I can buy or build that will stall power to a certain device in my circuit for 3 seconds when power is supplied, then will continue as normal?

    See diagram below

    [​IMG]

    Thanks
     
  2. Wendy

    Moderator

    Mar 24, 2008
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  3. VoodooMojo

    Active Member

    Nov 28, 2009
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    if you want to use transistors instead of a 555.

    the 0-20 seconds is an estimate.

    please amend if mistakes are present.
    I drew it up in a hurry.



    the 2N3904 is not the only usable NPN.
    I have almost a thousand of them so I use them where I can.
     
    tornado151 likes this.
  4. VoodooMojo

    Active Member

    Nov 28, 2009
    503
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    to answer your other question,
    yes, modules are available.

    attached are photos of a .1 to 10 second adjustable delay on timer.
    They come virtually all times from tenths of a second to days.

    the one in the picture costs about 20 dollars US.

    it will add a negative to a load after a delay.

    any more info needed, jusk ask.

    We are open here at AAC 24/7....literally.
     
    tornado151 likes this.
  5. retched

    AAC Fanatic!

    Dec 5, 2009
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    The item VoodooMojo showes is called a Delay-On-Make timer or relay. After it recieves power, it will delay the amount you pre-set then let the power continue.

    There are also Delay-on-Break to hold another line open after the power to a device is cut off.

    But here is a link to a whole bunch of 'em.
    http://www.airotronics.com/site/timing_delaymake.php
     
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  6. tornado151

    Thread Starter Member

    Apr 15, 2010
    34
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    Hi,
    Thanks for your replies. The modules look quite large, is there any really small compact (5volt) Delay-On-Make modules ? It only needs to dealy for 2-3 seconds.

    Otherwise I will have to make one myself?

    Thanks
     
  7. retched

    AAC Fanatic!

    Dec 5, 2009
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    2inches by 2 inches.. about 3/4 inch tall. Is that too big?

    You want something logic level?

    Bills 555 idea will do it. The timer starts when power is added.. Then after the pre-set time, the relay closes to complete the circuit.
     
  8. tornado151

    Thread Starter Member

    Apr 15, 2010
    34
    0
    Yea, unfortunatley it is too big.

    I will look into the 555 circuit. Ideally a pre-built 555 circuit would be great as I just needs this to finish a project off and I don't really want to have to mess around with it and buy all the components.
     
  9. retched

    AAC Fanatic!

    Dec 5, 2009
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    Jeesh... good luck with that. I have no resource to give you on that..
     
  10. Markd77

    Senior Member

    Sep 7, 2009
    2,803
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    Are you using the first one instead of a diode?
    I think it's connection is reversed in the second diagram.
     
  11. VoodooMojo

    Active Member

    Nov 28, 2009
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    The first 3904 is being used as a Zener Diode to increase the turn on voltage of the other two Darlington connected 3904s.

    on the V(BR)EBO spec at Electrical Characteristics of the datasheet it shows the breakdown voltage at a minimum of 6 volts. It is about 8 volts.
     
  12. lmartinez

    Active Member

    Mar 8, 2009
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    tornado151 likes this.
  13. tornado151

    Thread Starter Member

    Apr 15, 2010
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    I found that I already have spare 555 timer chip, so I am going to have a go at building a circuit with it tonight.

    Thanks for your help
     
  14. Markd77

    Senior Member

    Sep 7, 2009
    2,803
    594
    Thanks, I get what is going on now.
    Nice circuit.
     
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