Thursday, October 10, 2013

Digital Stopwatch 0-60sec

      By using the same circuit of the Digital Stopwatch 0-99sec we can add an AND gateand transform the 0 – 99sec stopwatch to a 0 – 60sec stopwatch.
                                                                We must find a way to control the RESET function of the BCD counter, which is responsible for the counting of the seconds. As we studied abovethe circuit resets when we have 99 to 100, that is 1001 1001 à 0001 0000 0000. To make a transformation successfully we must force the pulse from 59 to 60 0011 1001 à 0100 0000 on the output of the BCD counter.
     By placing the AND gate, with its inputs on the Qand Qof the BCD counter of the decades, we make sure that when the gate closes, the RST input of the BCD counter will be set to logical “1”, which on its turn, will force the circuit to start over. The transformed circuit appears in picture 2.

  Electronics Lab ,Created By Muhammad Irfan  Electronics Lab ,Created By Muhammad Irfan  Electronics Lab ,Created By Muhammad Irfan


  1. can you please tell me the values of the resistors ...cant differtiate between them

  2. y not g ,
    you also see this link

    brown,black,red = 10,00 = 1 kilo ohm
    brown,black,green = 10,00000 = 1 Mega ohm
    brown,black,orange = 10,000 = 10 kilo ohm
    brown,orange,orange = 13,000 = 13 kilo ohm = 10k ohm + 1 kilo ohm × 3

    OK .. thanks for view by blog