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.
Via the contact form.