Please Help -- "Power ON Delay Circuit Using 555."

Discussion in 'General Electronics Chat' started by famesethu, Nov 18, 2009.

  1. famesethu

    Thread Starter New Member

    Oct 25, 2009
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    Hey guys,:D

    I need to make a Power ON Delay Circuit with variable delay from 1sec to 10sec using 555 and a pot(variable resistor).
    That is when power is given to the circuit it must not produce an output until the delay time(say 1sec to 10sec).
    Providing a schematic diagram with time delay equation will be sufficient.
    Thank you.........:)
    Its Very Urgent.........
     
  2. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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  3. Wendy

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    Mar 24, 2008
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  4. famesethu

    Thread Starter New Member

    Oct 25, 2009
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    Hey Bill,what's the value for the other Resistors and capacitors...?
    In the T=1.1RC equation,R in ohms and C in farads or microfards.......?
    pls reply.
    i'm looking forward to your circuit......
     
  5. Safiya.Jan

    New Member

    Jun 18, 2017
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    What are the values of R1, C1, C2, R2?
     
  6. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
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    He wants a delayed pulse, you need to change the transistor for a Pnp, that circuit will operate immediately...
     
  7. Safiya.Jan

    New Member

    Jun 18, 2017
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    I want the relay switch to operate another circuit which will switch on after a delay, would that still be the same case?
     
  8. EM Fields

    Active Member

    Jun 8, 2016
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    555 _ON_ delay.png
     
  9. Wendy

    Moderator

    Mar 24, 2008
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    This is a standard monostablewhose trigger is the power on itself.The formula t.7Rt and=Ct applies. a 1Korm for the base resistor will likely suffice.R1=10K and C1=1uf

    Wendy's Index

    I have had stroke
    This jusr means I am not as sharp as usual.

    555 Monostable
     
    Last edited: Jun 18, 2017
  10. Wendy

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    Mar 24, 2008
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    Yes, The relay is to handle power
     
  11. EM Fields

    Active Member

    Jun 8, 2016
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    That's just a semi-standard 555 one-shot and won't work as a POWER-ON delay:
    Wendy\'s 555 non-delay.png
     
    Dodgydave likes this.
  12. Wendy

    Moderator

    Mar 24, 2008
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    But this is... *Wow this was started in the year2009

    [​IMG]
    R1=10K, R2 =1K
    Q1= 2N22222
    C1=0.1uf
     
  13. EM Fields

    Active Member

    Jun 8, 2016
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    Regardless, pin 2 will be low when Vcc goes high, (t0) which will unconditionally drive pin 3 high immediately instead of delaying its rise for t0 + 1.1RtCt.
     
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