During the reboxing, I connected the power to test again, and got that puff of smoke from the Nano that augers bad news all around.

Now I just get the power light and nothing else, so I think that Nano has had it! I’m hoping it was the rubber band pushing a wire on the board into another one causing a short, as I had done no work on the boards themselves. I’ll only know when I program a new Nano and put it in the board, I suppose…

I’m terrible at cutting and drilling those ABS enclosures, but I am good at handling a scalpel and metal ruler for paper/card work. So I’m going to see if I can make a simple enclosure out of 5mm balsa wood! If it works, it’ll save me a fortune in awfully botched plastic, and I’ll only ever have enclosures sized perfectly for the job!



To connect to the Bubble Display module, I mounted it on a piece of Veroboard, with the rails cut between the 2×6 pins. I left one row of extra holes on each side, and mounted some 90 degree header strip there, exposing the 12 pins at right angles to the display. I then took two length of 6 strand ribbon cable, put 6 way Molex connectors on for plugging into the display. But on the other end of the ribbon, I put 12 individual connectors on, this way, it was easy to match the bubble pin number with the correct shift register and pin at the board end. I do need to find some nice soft flexible cable though, all the stuff I seem to have is really stiff, and doesnt like being bent at certain angles!

I love it when things work first time. This wasn’t one of those occasions though! I had a problem where all of the output pins of the 2nd shift register were always high, meaning no digits on the display. It took some work with the voltage tester, but it was tracked down to a minute piece of stray solder, bridging two strips on the veroboard.

So the project is complete, barring the enclosure (currently the two boards are being held together by an elastic band with a piece of hard plastic in between!). So when I find a suitable sized enclosure, I’ll transfer it into there, but in the meantime, I’ll put up the board layout for the extra board, and the full code, once I add some comments.

There are just 2 points of connection between the original board and the new bubble display board. A twin connector to the ground and 5V on the bottom right, and a triple for the data, clock and latch. Fortunately there were three unused outputs from the Nano with unused rails. That’s the 2nd red box at the top.


How do you find the right container for a project. How do you make the cuts and holes for the bits you want on the outside? I hate this bit… It turns a beautiful bit of neat electronics into a messy clump of duck taped rubbish…

Here is the first step for part two of my cooling project. It uses just 3 outputs to drive a pair of shift registers, and ultimately a 4-digit bubble display!

Currently the display toggles between displaying 24.5C and 1496 (the RPM)… Why? Because those are the two hard coded values I’ve picked in my function calls!

Given its only 3 pins, my plan is to put it all on a different bit of Veroboard, and connect it to the original board with a plug! Exciting stuff 🙂