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4018 Div by N - help needed

Discussion in 'Electronic Basics' started by Phideaux, Jan 3, 2004.

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  1. Phideaux

    Phideaux Guest

    I need a little help from someone with experience with this particular
    IC. I am using it along with two 4017 decade counters to divide a
    clocked input by 700 and then send a positive pulse out to reset the
    circuit. I've never used this chip before and am a little puzzled as
    to the proper set-up. You know us mechanical people, a little slow on
    the up-going stroke. Thanks in advance.
  2. George

    George Guest
    This data sheet has how to set up the 4018 to divide by 7 on the 6th
    page of the pdf. It shows the complete circuit. You need two NAND
    gates (or one and an inverter, but just link the inputs of a NAND gate
    to get an inverter). Feed the CL/7 output from 4018 (its on the
    circuit diagram on the data sheet)into the clock pin of a decade
    counter and feed the "9" pin (pin 11 on the DIP I've seen) from that
    into the clock pin of the second decade counter. The "9" pin (pin 11
    again) from that will output a pulse on the 700th clock cycle put into
    the 4018 clock pin. Hope this helps.
    P.S. the data sheet for the 4017 is:
  3. George

    George Guest

    Oops I reread the timing diagram and hook up the "0"pin of the 4017s
    not the "9". Either that or detect the rising edge of the carry out
  4. George

    George Guest

    Use the carryout pin. After more reading, the 4017 detect the rising
    edge of the clock. That means the carryout pin will work well. Just
    make sure you ignore the initial pulse on reset.
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