Finished my TTL clock design

Discussion in 'The Projects Forum' started by bitrex, Mar 11, 2010.

  1. bitrex

    Thread Starter Member

    Dec 13, 2009
    I haven't posted here in a while, so I thought I'd put up what I've been working on in my spare time. I have a lot of 74LS series TTL logic chips I got on an Ebay auction, so I designed a digital clock to put them to use. This design has 4 digits and is switchable between 12/24 hour modes with leading digit blanking; it is set up to generate its clock from the power line frequency but has a switchable input for a 1 Hz signal from an external source. I plan on constructing the final version with Numitron tubes, but it can be used with 7 segment LEDs and probably Nixies with some modifications and changes to the chips used in the BCD decoding. It uses about 20 TTL ICs - a tribute to obsolete tech. :) Any comments or critiques would be welcome!

    Hopefully the next project will be a circuit to receive and lock to the 1 Hz signal from CHU Canada, which I can usually pick up quite strongly in my area and when available will make a better timebase for the clock.
    clifton17 likes this.
  2. retched

    AAC Fanatic!

    Dec 5, 2009
    Wow, she's a beaut! Good job.
  3. jgessling

    Active Member

    Jul 31, 2009
    I have designed a similar project that I now am in the process of soldering up. Like you I had a collection of TTL , I had gotten mine from flea market purchases. You can find my design in the "Projects collection" forum. Mine's a bit simpler since I went with a 24hr clock and had some different chips. Nice to see your work, it looks great.