Digital clock - counter

Discussion in 'The Projects Forum' started by Allumiin, Jun 5, 2016.

  1. Allumiin

    Thread Starter New Member

    Jun 5, 2016
    Hello everybody, uni has ended and I should be hopefully finishing next year.
    Im starting to think what I should do for my bachelors degree thesis. I want to make something tangible and reasonably easy, I figured a digital clock out of discrete components.
    I have alot of the stuff figured out at the moment, I am posting this to ask about the counter.
    I am looking to make the counter reliable and with the least amount of components, and I need to set the seconds/minutes/hours and reset everything.
    My questions are:
    1) Which trigger should I use for this ? JK ?
    2) Should I use a synchronous or asynchronous clock setup ?
    3) Is doing it with discrete components overkill ? Thats alot of transistors
    For now all I want it to do is to count time, no extra features yet. Could somebody with a bit more handson experience suggest me a counter setup ?
    Thank you for reading.
  2. dl324

    Distinguished Member

    Mar 30, 2015
    Welcome to AAC!
    The policy on this site is that projects and homework for which you will receive a grade cannot be answered directly. We're expected to guide students to solutions so they can learn. Answers below will be in that vein.
    You mention discrete components and JK flip flops. Is it your intention to implement flip flops with transistors or to use SSI IC's in combination with discrete transistors?
    If you mean 1 second oscillator/time source. Will this be battery operated, AC operated, or both?

    What are the advantages and disadvantages of using line frequency, crystal oscillator, or RC oscillator?
    What are the advantages/disadvantages of synchronous vs ripple clocking? Does it matter for your application?
    You're right, it would be a lot of transistors. How many would it take to implement a JK FF? Which FF would require the least number of transistors?
    12 hour only, 24 hour only, or selectable? How will you set the time? Increment/decrement seconds or have some more convenient method (like counting backwards or being able to set H/M/S individually)? If you're going to go to the bother of designing a clock, I'd add some nice features like a large display with discrete LEDs (5x8 character matrix), an LED pendulum that mimics the speed of an actual mechanical pendulum, chimes at the top/bottom of the hour, if AC powered, battery backup to maintain correct time.