555 as Toggle Switch

Discussion in 'General Electronics Chat' started by shahtiaz, May 31, 2012.

  1. shahtiaz

    Thread Starter New Member

    May 30, 2012
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    Dear Lubnan!

    can you send me the picture of your final toggle switch... where you have applied 10K resistor with 100uf Capacitor...

    I tried the same but didn't workout for me...

    please help...
     
  2. shahtiaz

    Thread Starter New Member

    May 30, 2012
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    0
    Please provide me the picture of this toggle switch... this not working for me :(
     
  3. absf

    Senior Member

    Dec 29, 2010
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    Should be something like this...
     
  4. Wendy

    Moderator

    Mar 24, 2008
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    Welcome to AAC!

    A thread belongs to the OP (original poster). Trying to take over someone elses thread is called hijacking, which is not allowed at All About Circuits. I have therefore given you a thread of your very own.

    This was split from 555 Toggle switch problem.

    I helped design a very similar circuit. What are you having problem with?

    555 Bistable Multivibrator
     
  5. Wendy

    Moderator

    Mar 24, 2008
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    [​IMG]

    Much as I hate to disagree, that will not work. The larger capacitance will swamp the smaller, and the smaller capacitor is the "memory" of the circuit.
     
  6. absf

    Senior Member

    Dec 29, 2010
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    Agreed. So the value of 10uF capacitor has to be smaller than C1, right?

    Allen
     
    Last edited: Jun 1, 2012
  7. Wendy

    Moderator

    Mar 24, 2008
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    No, eliminate the 10µF entirely, not needed or wanted. You will get greater benefit if the power supply Vcc is filtered.

    Same thing with the parts on pin 4, Pin 4 just needs to go to Vcc, nothing more.

    ****************

    No, I'll take it back about pin 4, it makes the 555 assume a definite start up condition. You can do the same thing with a really small cap on pins 2 & 6 which could go to either Vcc or ground. It is an either or, not both.
     
    Last edited: Jun 1, 2012
  8. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    I recall a thread from a few months(?) back, where the OP was going nuts with false triggering. IIRC, I recommended a small cap on pins 2&6. That node was apparently picking up EMI from the relay switching. I think the cap was about 10% of the memory cap.
     
  9. Wendy

    Moderator

    Mar 24, 2008
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    I can believe it, but it also selects the power up state of the toggle.
     
  10. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    Unless you also use a power on reset RC on pin 4, and make the reset time constant longer than that at pins 2 & 6.
     
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