MOD 6 Countdown Timer

Thread Starter

Lijah Samarzia

Joined Nov 5, 2014
1
Hello, I am currently constructing a countdown timer to count down from 4 preset times (30 minutes, 15 minutes, 12, minutes, and 8 minutes). I have everything installed and correctly working (including my presets) EXCEPT my "tens of seconds". I have been racking my brain trying different things and I can not get a MOD 6 to countdown (properly). I'm using 3 JK flip-flops and have it counting down from 7-0 (MOD 8). When I add a logic gate to make it a MOD 6, for some reason it is making it a MOD 5. I can not figure out my error. Does anyone have any hints or tips for me? I'm using IC 74112's feeding a 7447 and then into a 7-segment display. Any help would be appreciated. Thanks.

p.s. should I abandon this and attempt a MOD 60? I had a little trouble getting that to count down. I didn't spend too much time on it though.
 
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