For the 14 segment display, rather than using a 18650 cell or what not, you could use a straight 5v USB battery pack, assuming you get one that'll do 2+ amp out, and use this buck to take it down to 3 ...
Reddit user Krukerfluk has created an awesome DIY digital clock using 144 x seven segment displays, combining them to create a larger LED display powered by an Arduino Nano. The small Arduino ...
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