SPI was a standard library for arduino. I guess either you don't have it installed, or you have it deactivated. I'm not too sure, I haven't played with this for a while and I know the arduino ide has evolved over the last years... But I would guess it's because that library is missing for you.
I don't think I tied the LED strip second power supply back into the arduino. It goes just to the strip. If you look at:https://www.instructables.com/file/FPKO4BTHQ410SD4/you will see that there is a red/black pair coming from the big power cable that goes out the bottom, that doesn't go to the arduino, it just goes through the hole in the board. That's the two wires from the second power supply. The red and black coming out of the arduino go to the 7-Segment LED and the pads.Good luck! Be sure to post an I-built-it link, as I'd love to see how yours turns out@
We have a bunch Adafruit lipo chargers lying around. I think we probably use this one: https://www.adafruit.com/products/1304
Here's the spec sheet: http://www.nxp.com/assets/documents/data/en/data-s...It says .1m resolution. But I'm sure accuracy depends on calibration.
Or maybe this one from Sparkfun: https://www.sparkfun.com/products/10217 I think they both work.
Nope, it's just what I had lying around and I thought they looked pretty. In fact, countersunk screws would be better because the ball sometimes hits them and bounces in a weird way.
It should just come right on. It's possible that the libraries have changed a little since I wrote the code, so you should look at that and see if there's any other steps they've added.
Looks like you can still get it here: https://shop.pimoroni.com/products/retro-4-digit-led-display
Also you can find it on ebay search for qdsp6064
simple user-adjustable DIY Nixie Clock