J-K Flip-Flop - How It Works




About: Retired teacher and High School Principal. Teacher of math, science, digital electronics, computer leteracy, computer programing

The J-K Flip-Flop IC is used to shift data from one point to another in a circuit in a timed fashion using a clock/strobe pulse to control the data flow. The J-K is also used as a binary counter. The number of bits in the counter byte is determined by the number of J-Ks that are linked (output-to-input fashion). As a teacher I found the J-K ideal for teaching the concepts of data shifting (control) and binary counting. My students could underatand these concepts easily enough. However, they had great difficulty visualizing the workings of the Flip-Flop action which accomplishes these tasks. I wrote a program that graphically and dynamically depics what happens inside the J-K chip - MODES (master,slave), HI and LO activated, POSITIVE and NEGATIVE logic, STROBE, PULSE, LEADING and TRAILING pulse edges, WAIT state, DISABLED state, SYNCHRONOUS and ASYNCHRONOUS operation.

I expect that not many hackers who frequent Instructable are interested in the topic, but for those who are, enjoy. My students did (I am retired).

When you RUN the JKFF.EXE program, wait a few seconds for the program to load and auto-execute.

Note: Ignore the address information in the title page.

Step 1: J-K Flip-Flop Layout

This is a dual J-K chip with not inner connections between the individual J-Ks.



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    9 Discussions


    6 years ago on Introduction

    any diagram showing how to wire a 1 button switch so you can use it to toggle it on and off?


    10 years ago on Introduction

    i downloaded the executable, no virus warnings, and my pc is still working.


    11 years ago on Introduction

    Good, but better would be if you actually built this on a breakout board and used LEDs. Then video it.


    12 years ago

    This, and your trig function program, look somewhat interesting, but I'm not at all happy with the prospect of downloading a random executable (and running it) to get any benefit of the "project." Could you at least include some screenshots and such as examples of how the application is supposed to work?

    2 replies

    Reply 12 years ago

    Hi westfw: Your comments are well founded. I appreciate your concerns. I have little time to do much at the moment but I will attempt a more constructive response latter. As background information let me say that I wrote the programs in 1989 and used them as teaching aids with my students in Calculus and in Digital Electronics classes. As both author and instructor I was on hand to guide student as to usage of the same. I realize that the menus are a bit cryptic and not user friendly when used outside the classroom context. I ran sucurity checks on the files before posting them and found them to be clean. Thanks for your comments. Sincerely, Richard


    Reply 12 years ago

    Nothing personal, but I was more worried about YOU being a virus-writing cracker, rather than having posting accidentally infected executables (in which case, your reassurances don't mean anything.) I don't know how to solve this problem in general; the sites that normally make executables downloadable presumably go to a lot of effort to ensure no viri slip through; I assume the Instucatbles sire does not yet do that, and might not be interested in doing that. You could post source code; for some reasons people find that more trustworthy, even though they don't (or can't) look at the source carefully enough to see whether it contains malicious code.