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Topic: Yet Another (4017) Clock (Read 1340 times) previous topic - next topic

Yet Another (4017) Clock

This is a clock based on 4017 decade counters, to be entered into the 7400 comp once finished, it displays 12 hour time on four 7 segment displays.

[attachment=5]There are four counters which divide the input frequency by a factor of ten for the first and third counter (least significant digit of minutes and hours), a factor of 6 for the second counter(second digit of minutes), and a factor of 2 for the fourth counter(second digit of hours)
Each digit is represented by the current output of their respective 4017 counter. The output of a 4017 consists of 10 pins which each represent a value from 0 to 9, the pin driven HIGH increments with each input pulse until the reset pin is pulled high or the counter rolls over from 9 to 0.

[attachment=4]As the 4017 can not directly drive a 7 segment display, a solution was needed, I searched around in my small collection of IC's and found two 4001 quad NOR gates, and attempted to rig something up, I gave up halfway after popping a transistor (and realising I didn't have enough gates to make 4 drivers)  and decided to just brute force it with diodes. Not a great idea for actually prototyping when you only have smd diodes. But it worked :). The NOR gates were later used in an AND gate configuration to enable the reset pin on the hour counters when output 1 of the most significant hour digit and output 3 of the least significant digit were high.

After realising I only have 16 MHz crystals, I decided to use a 555 timer as a clock source (according to my nidaq it runs a few seconds fast at 58~ seconds between each pulse).
I have breadboarded each part of the clock, now soldering it all together, not finished yet though.

Re: Yet Another (4017) Clock

Reply #1
Nice work, cool to see your development process too.
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Re: Yet Another (4017) Clock

Reply #2
Thanks, I should have it finished soon unless school gets in the way.