0 to 30 BCD counter - Pls help

Discussion in 'The Projects Forum' started by Deea, Nov 18, 2006.

  1. Deea

    Thread Starter New Member

    Nov 18, 2006
    3
    0
    Hi,

    I really need help on one of my projects and hope that somebody can help me.

    I am referring to this schematics at

    http://www.doctronics.co.uk/4510.htm#test circuit

    Pla take a look at the 2 digit BCD counter with NOT and AND gate somewhere in the middle or below of the site. From the schematics, it shows how to reset on count 60. Thus to reset on any whole TENS number would be fairly easy.

    But my problem is, i need to count until 30 which means that my reset count will have to be 31. Could you pls help me on how i can modify the circuit to make it count till 30 instead of 29?
    Thank you sooo much.

    Sincerely in need of help:confused: ,

    Alesha
     
  2. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    You might consider trying the following setup:

    Step 1: Move the two diodes from the B and C output of the TENs counter to the A and B output of the TENs counter.

    Step 2: Add a third diode that connects from the A output on the UNITs counter to the junction of the 10K and the other two diodes.

    That way the reset for both counters will require that all three outputs connected to the AND gate are in the high state. If works like I think it will, the counters will have to reach the end-count 31 before the conditions for reset are satisfied.

    hgmjr
     
  3. Deea

    Thread Starter New Member

    Nov 18, 2006
    3
    0
    Thank u soo much for the reply.

    From the connection u mention, u are taking A as the LSB right? Bcoz i'm taking A as the MSB and D as the LSB. Pls correct me if i'm wrong.

    And 1 more question.

    Wen i get my circuit to work, my LED display for the 1st 10 count will be displayed in the UNITS section in 1,2,3,4,etc form right? It won't be displayed in the TENS section in 01,02,03,etc form with 0 in the units section and 1,2,3 in the TENS section? So i can say that for the 1st 10 counts, the 2nd BCD counter can be considered as inactive?

    I'm kind of confused on what they mean by UNIT and TENS section. Do they mean that i should connect my 1st LED for my counts to the 2nd counter or something since it's in TENS?

    So sorry for the questions. I would have experimented myself but I need to write and submit a summarized report of my findings before i have access to the lab. Thanks.
     
  4. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    My bad. You are correct. I meant for you to use the LSB (the D output) on the UNITS counter. Also for the same reason, I was similarly mistaken in my description of the relocation of the diode connections for the TENS 4510. You will need to connect the diodes to C and D on the TENS 4510.
    Right. The 4510 labeled UNITS in the diagram should count from 0 up to 9 during which the 4510 labeled TENS should remain at zero. Once the UNITS 4510 reaches the count of 9, it will return to 0 at which time the TENS 4510 will advance to the count of 1. This should continue until the TENS counter reaches 3 and the UNITS counter reaches 1. This should reset both counters to 0 and the count should begin again.
    UNITS refers to the least significant digit in the base-10 numbering system. It is also sometimes referred to as the ONES digit.

    No problem. Sorry for the momentary confusion I may have caused.
     
  5. Deea

    Thread Starter New Member

    Nov 18, 2006
    3
    0
    Thank you so much for clarrifying..

    Really appreciate it. =) Thanks again.

    Sincerely,
    Dee
     
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