Protip: if you want to experiment with running a seven-segment LED display off an Arduino or other microcontroller without using all your digital I/O pins, buy a cheapie electronic counter kit. Fifteen bucks gets you your two-digit display, two 4543 BCD-to-7-segment-LED latch/decoder/driver controller chips (socketed, so you can appropriate them for your real project), the right number of the correct value current-limiting resistors and other passive components *plus* a neat circuit diagram and an easy-to-hack prototype when you’re done. And all this with only one trip to the shops! (This is the initial experiment for version 2 of the Technocolour Dreamcoat; next step is to get the Arduino to read values off a rotary encoder, which I’ll use to select which numbered animation to show. Stay tuned…)

Protip: if you want to experiment with running a seven-segment LED display off an Arduino or other microcontroller without using all your digital I/O pins, buy a cheapie electronic counter kit. Fifteen bucks gets you your two-digit display, two 4543 BCD-to-7-segment-LED latch/decoder/driver controller chips (socketed, so you can appropriate them for your real project), the right number of the correct value current-limiting resistors and other passive components *plus* a neat circuit diagram and an easy-to-hack prototype when you’re done. And all this with only one trip to the shops!

(This is the initial experiment for version 2 of the Technocolour Dreamcoat; next step is to get the Arduino to read values off a rotary encoder, which I’ll use to select which numbered animation to show. Stay tuned…)