MICROCONTROLLER BASED VISITOR COUNTER.

Discussion in 'Embedded Systems and Microcontrollers' started by SSMNITHMR, Feb 22, 2009.

  1. SSMNITHMR

    Thread Starter Member

    Feb 22, 2009
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  2. Arm_n_Legs

    Active Member

    Mar 7, 2007
    183
    10
    T1, T2, and T3, are used to provide the multiplex driving of the 7-segment display. At any one time, only of the the transistors is turned on to provide power supply to the digit.

    For example, if you want to display the number "123". You provide the data for "1" on the port and drive the 1st display while turning off the 2nd and 3rd display. Then provide the data for "2" and turn on the 2nd digit, and so on.
     
  3. t06afre

    AAC Fanatic!

    May 11, 2009
    5,939
    1,222
    Mike just a friendly tip :) Check the data of the original post. Not that it is wrong in any way, or gainst any forum rule. But replay old postings will probably not be of any help. The user will be long gone or the project ended
     
  4. vikas kaushik

    New Member

    Feb 22, 2012
    1
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    no one here explained the working of Q1 & Q2 transistor...if anyone know .. post it here asap .. :)
     
  5. Potato Pudding

    Well-Known Member

    Jun 11, 2010
    684
    92
    Those transistors are amplifying the sensor inputs to drop the trigger level on the 555.

    The transistors take their base bias drive from the sensors which will switch the transistors on and off. When they switch on and their collector drops the 555 trigger, the monostable circuit will send a pulse.
     
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