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Timer and Counter and then to LCD

Discussion in 'Electronics Homework Help' started by Kldnz, Jan 11, 2016.

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  1. Kldnz


    Jan 11, 2016
    Hello, I'm fairly new here. I have this little trouble. i need to do a timer that sends an impuls every 30sec from that I need it to go to a counter which counts from 0 to 9 and then resets back to 0. I can deal with the timer i just need the calculations for resistors and capacitors. The thing is that the only counter I know Is 74LS193D (multisim) and it counts to 15 and i only need to 9 and then it to reset back to 0 and go on agian. So i would like to know if any of you know a counter in multisim that counts to 9? Maybe the same 74LS193D does that but neads to load differently?

    And there is one more catch i need to deal with is that I need the coounter to start at 0 when I give the impuls from Timer.
    Because I need to make this project like it counts how much you need to pay and the first 30sec are free. So i need it to start at 0 then go to 1 and etc. But for me it starts at 1... So if anyone could help me with these questions I would be verry glad.

    To sum up I need a counter that counts from 0 to 9 and resets back to 0 (the one I have done starts at 1 and counts to 15)

    Please help me anyone ;/
  2. hevans1944

    hevans1944 Hop - AC8NS

    Jun 21, 2012
    The 74LS193D can be reset asynchronously, and also loaded asynchronously independent of the "up" or "down" synchronous clock pulses you apply every thirty seconds. Just decode the four counter outputs to either nine or ten (if you want it to stay at the nine count for thirty seconds) and apply the decoded high-level output to the reset input to reset to zero.

    To decode a "9" apply Output Qa and Output Qd to a 2-input AND gate. Connect the AND gate output to CLR. The counter will reset to "0" when a count of "9" is reached.

    To decode a "10" apply Output Qb and Output Qd to a 2-input AND gate. Connect the AND gate output to CLR. The counter will reset to "0" when a count of "10" is reached.

    To make sure the counter starts from zero, connect Input A, Input B, Input C, and Input D to logic common. Use a power-on reset circuit to apply a logic zero pulse to the /LOAD input.

    Go to this website, download the PDF datasheet and read it.

  3. Kldnz


    Jan 11, 2016
    Thank your for your help but i already fixed this problem. Found a another counter 74LS93N how i connected to a timer is shown in the photo I uploaded. But I ran into the problem that when the power is cut off the LCD display shows the number it showed. Although I'm going to try doing with the 74LS193D with how you mentioned it. :)

    Edit: I tried with 74LS193D but somehow it didnt work for me... or i made some mistakes.
    But can anyone help with the 74LS93N and the scheme i sent in a picutre to help me reset it every time i give VCC to it. Because now when i turn it on it counts normaly. But when I turn of the VCC supply the numberstays same and continues when i turn it back on. Another problem i ran into was that i need it to make it count to 6 bikes and when i turn them all in the simulations crashes maybe because of overloading?

    Attached Files:

    Last edited: Jan 12, 2016
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