Homemade TTL Circuit 24-hour Digital Clock


Introduction: Homemade TTL Circuit 24-hour Digital Clock

After taking an intro-level EE class at my local community college I decided to make a digital clock with basic  ICs and 7-segment displays. The previous pictures show the process of making it over the course of about a month.

You can easily replicate this clock as I have included the logic diagram as well as a map of the actual ICs I used with their pin numbers and inputs labeled. The displays on the IC map are dual 7-segment common cathode displays. The software I used to create the schematics is LogicWorks 4.1.

Not included in the schematic is a 32KHz Crystal Oscillator (digikey.com part # DS32KHZ/DIP-ND) which is divided down to 1Hz using a 14-bit counter and a JK flip-flop in toggle mode. That signal is then fed to the first counter in the sequence which is used for the seconds portion of the clock. The switches used for the time set are SPDT momentary push buttons. When pressed and held, the 1Hz signal is forwarded to the targeted bit, which makes it temporarily count at a 1 second rate. The button is then released when it reaches the desired value. The bright blue LEDs seen inside the clock can be turned on or off (they can be slightly obnoxious when left on at night) with a basic on/off toggle switch that's on the back of the clock among the time set buttons. All other non-circuit related hardware, wood, etc. was purchased at Home Depot.



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    8 Discussions

    how much resistance you use on seven segment?

    Ola vc poderia me enviar os componentes para esse circuito? Nesse caso o Flip Flop é tipo D?


    can you email me the pdf file

    pls i need to do this and i have a few questions concerning the schematics



    2 years ago

    What does the .PDF include, i want to know if it includes the step by step on how to make this for my project?


    3 years ago

    Can i see you litar flip flop. Because i have to do my final project and i think i want to do this project.

    1 reply

    Hi buddy do u have this project PDF file ? please send me here


    I agree with emilyvanleemput! I would love to make one of these myself! Even to have it in 12 hour time format.