555 Monostable Operation

Discussion in 'The Projects Forum' started by Acey, Feb 19, 2015.

  1. Acey

    Thread Starter New Member

    Feb 18, 2015
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    Is there any use for reset pin 4 in monostable operation? Cannot find any info on this.
     
  2. ScottWang

    Moderator

    Aug 23, 2012
    4,854
    767
    What do you want for the reset function?
    You can try it when it connecting to Vcc and Gnd, what do they have any difference?
     
  3. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,986
    745
    The reset pin 4, makes the output pin 3 instantly to gnd when its taken to ground ,for normal operation the reset pin is kept at posative pin8.
     
  4. Acey

    Thread Starter New Member

    Feb 18, 2015
    4
    0
    I'm just trying to figure out exactly what the pin does, maybe in the hopes of simplifying a circuit that uses 2 timers. If grounding the pin can be used to deactivate the 2nd timer, that could be useful for my application.

    Thank you.
     
  5. ScottWang

    Moderator

    Aug 23, 2012
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    767
    What I knew the methods to control a 555 astable to stop generate the pulse as :
    1. Using a PNP bjt to control from Vcc(pin 8) with a low level in base.
    2. Using an NPN bjt to control from Gnd(pin 1) with a high level in base.
    3. Control the reset pin (pin 4) to Gnd.
    4. Control R1 to Gnd. (see astable circuit)
     
  6. Reloadron

    Active Member

    Jan 15, 2015
    963
    232
    Read this thread which seems eerily close to what you are asking about. Really a striking similarity.

    Ron
     
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