How would I design a circuit made of rising edge triggered flip flops and inverters to make its output 1/6 of the clock frequency. This is what I was thinking Cheers

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    \$\begingroup\$ So what is wrong with the circuit on your(?) drawing? \$\endgroup\$
    – Eugene Sh.
    Commented Mar 24, 2015 at 14:23
  • \$\begingroup\$ The solution is a 3 bit Johnson counter, which is already displayed in your question. \$\endgroup\$
    – Paebbels
    Commented Mar 24, 2015 at 20:34

2 Answers 2


We don't just outright give answers to homework problems here, but will help you to solve them yourself if you cooperate.

First, take the prime factors of 6 to see if the problem can be broken up and simplified. Powers or 2 can be directly realized by binary counters.

The factor of 3 makes this more interesting. 3 is a low number, so one option is a chain of flip-flops. Other ways to divide by arbitrary numbers is to use a binary counter, then reset it when it gets to a certain value. Look up something called a divide by N counter.

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    \$\begingroup\$ Thanks for your help. I was just looking for some direction not so much the solution. Now I know for next time. \$\endgroup\$ Commented Mar 24, 2015 at 14:37

The indicated circuit, with the clocks of all the flip flops wired together, is likely to generate a square wave output of the desired frequency. There is a potential problem with it, however, that might cause it to output 1/2 of the input frequency rather than 1/6. Can you see what might cause it to output the wrong frequency, and replacing the inverter with something else might help cure the problem?


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