7400 competition entry: Wheely bin night reminder

Luc entered his Wheely bin night reminder into the Open 7400 Logic Competition:

Because the competition was so open ended in its brief, I placed two constraints on myself:

First, I had to make do with the logic chips (and other components) I had on hand. No going to Jaycar or placing an order through Element 14; only junkbox parts allowed. I had more 4000-series parts than 7400-series parts, so the design is based on 4000 CMOS logic. Because of this constraint, it is sub-optimal in many ways – requiring more parts than had I had access to the more highly integrated CMOS parts.

Second, I had to make something that solved a problem I faced. I always forget to take the bins out on bin night. What I needed was a system of reminders. Sure, I could have set an alarm on my phone. But what would be the fun in that. So I set about designing the logic system required to remind me that:

  • The Red (garbage) and Yellow (recycling) wheely bins go out weekly on a Monday night.
  • The Green (green waste) wheely bin goes out on a Tuesday night on alternate weeks.

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