Disco Drinks Coaster

Step 4 A warning and a tip

A couple of words of warning. Modern LEDs can be very bright indeed. You could probably hurt yourself pretty badly by dialling them up to full intensity and ignoring your look-away reflex, so don't. Also, when debugging your firmware it is easy to stall the scanning process and burn out the precious LEDs. Use a decent current-limited bench power supply, with the current dialled back to a few tens of milliamps to avoid this happening.