Please helpp me to switch

Discussion in 'The Projects Forum' started by cityhunter, Mar 12, 2013.

  1. cityhunter

    Thread Starter New Member

    Mar 8, 2013
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    how can i use an IC as switch to turn on a NE555 IC?
     
  2. absf

    Senior Member

    Dec 29, 2010
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    371
    You can either switch on the NE555 by controlling its Vcc pin (8) OR reset pin (4). But what triggers the IC in question that switches on the 555?

    Allen
     
  3. cityhunter

    Thread Starter New Member

    Mar 8, 2013
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    0
    a logic 1 will let the ne555 turn on.

    my plan is to have a ne555 time delay with 10 seconds, and if this 10sec is switched on, another ne555 but astable circuit will run. if the 10sec is already finished, the astable circuit will also be turned off.
     
  4. cityhunter

    Thread Starter New Member

    Mar 8, 2013
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    in short, i want 10 seconds of flashing led. when a logic 1 is sent by an IC.
     
  5. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    That's the purpose of the RESET pin on the 555 timer, when held at logic 1 (5v) the 555 oscillator will run, when the RESET pin is held at logic 0 (0v) the 555 timer will stop running and be in reset mode. :)
     
  6. absf

    Senior Member

    Dec 29, 2010
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    I see. You can use one 555 configured as mono-stable to control another 555 that is configured as astable like the circuit attached.

    Allen

    [edit] The schematic uses 9V DC but can be reduced to work on 5V. If triggered by logic "1" put an inverter or a NPN transistor to replace the button at pin 2 of U1.
     
    Last edited: Mar 12, 2013
  7. #12

    Expert

    Nov 30, 2010
    16,255
    6,754
    PS, there s a chip called, "556" that has (2) 555 chips inside it.
     
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