Setting Digital Clock Conumdrum

Discussion in 'General Electronics Chat' started by edwardholmes91, Mar 21, 2014.

  1. edwardholmes91

    Thread Starter Member

    Feb 25, 2013

    I am currently working on a project to design and build a BCD clock. I managed to obtain an old book called "Discovering Electronic Clocks - W. D. Phillips" which is very useful.

    To start with I am looking at the basic clock design in chapter six. This uses a 32.768KHz crystal, a few capacitors and resistors, a 4060 counter and 4013 flip flop to generate a 1Hz signal. After this a 1Hz 64Hz and 2048Hz signal is fed into a channel selector and three buttons: "Allow", "Slow" and "Fast" are used to set the time. I feel that this arrangement isn't the most elegant because the clock can't be set accurately. The 1Hz signal is used to clock 6 cascaded decade counters (4518s - two in each package) and then these feed some 4511 7-segment display drivers.

    My intention initially is to replace the channel selector with a 40106 Schmitt Inverter to de-bounce three switches. One to reset the seconds, one to clock the minutes and one to clock the hours. All is fine with the seconds reset and the hours and minutes clock buttons work... but only when the seconds or minutes are outside of 40 - 59 seconds, because of the way that the 4518s are wired.

    Unfortunately my software won't simulate the crystal properly, so I am taking out the channel selector and 4060 for the time being and just injecting a 1Hz signal from the software.

    Please see the attached diagram.

    Looking forward to any comments or suggestions.

    Kind Regards

    Last edited: Mar 22, 2014
  2. edwardholmes91

    Thread Starter Member

    Feb 25, 2013
    Any ideas anyone? I'm thinking it may be easier to just ignore the design flaw and accept that you need to power on, hold the seconds reset and then set the hours and minutes before releasing the seconds reset?
  3. GopherT

    AAC Fanatic!

    Nov 23, 2012
    Seems easy enough.

    On another topic, Have you ever posted the follow-up of your summer camp experience?
  4. Wendy


    Mar 24, 2008
    Digital clocks

    This shows how I did it. Project not finished, but that section works.
  5. alfacliff

    Well-Known Member

    Dec 13, 2013
    one of the better digital adjustment techniques I have seen involves how long a set button is held down. if you just press and release, it affects the lowest digit, if pressed and held a few seconds, it steps the digit faster, if held longer, it sets the next digit in order the same way. I have seen this on industrial temprature controlls, and my alarm clock radio.
  6. Kim Alfred

    New Member

    Jan 30, 2015
    Hi Edward, we're also going to make this one so I just want to ask if you successfully made it? Thanks!