Another mentor and I built a countdown clock as a gift to our team. It was something I wanted to build since 2016, but the cost of the 7" 7-segment LED display was expensive ($20-25 per digit). We a 3d printer, arduino nano, and neopixels we could build for a more affordable cost.
It boots up, displays our team number, connects to wifi to get the current time. Then it calculates the time remaining between the current time and a target date/time. Currently it’s counting down to Kickoff (1/6 10a EST). Once it hits 00 00:00:00 it displays “ALL donE”. After that it will count down our first event. The team and mentors liked it. Hopefully they still will when just days left, lol.
We 3D printed these large 7 segment display frames. I printed in white PETG, after testing we get a glow in the non-lit segments from the adjacent lit segment. You can see this in 1 in the hours above, the top middle and bottom horizontal segment next to the 1 has a glow. Printing in Black filament will help reduce that. The 2 colon segments were a manual design I CAD’ed that copied the frame from the 7 segment display. I just used their diffuser with a small opening in the frame cover to make the colon.
In the photo of the clock on the table, you can see on the space beneath 10:38 we have a lot of wires. I couldn’t fill that in with rigid foam insulation so the wood grain contact paper ripples some. Also, I couldn’t get a smooth top surface, event though I made the wooden perimeter the same height as 1" rigid foam insulation.
We are in the process of redesigning the clock design. We really want a flat smooth clock face surface. Our first design was using this video bases of our 7 segment display (https://www.youtube.com/watch?v=r_yobwaBWr0).
We had issues with wire gauge, all leds on would draw more amps. We ran power to each 2 digit number group, instead of daisy chaining them in one big line of LEDs. The power for every digit pair went straight to the power supply.
Our next version we’re going to use this design approach https://www.youtube.com/watch?v=pyFtAkwqVZ4 I think the separate segments of the digit will eliminate the bleed through. The acrylic face plate will give flat front surface we’re looking for.
Well get our code up on github. We have an additional clock feature we want add. We’d like the clock to pull the stop time from a github checked in file. This way changing the target date is as simple of checking in a new time. to github
I’m free to answers any questions. This weekend we’re at an off season comp, so I likely won’t reply to Sun evening.
