Sewing a LilyPad LED Circuit

Pin a LilyPad LED and a LilyPad coin-cell battery holder a few centimetres apart on a piece of felt. Find each board's + and - sew tabs, and plan two thread paths — one joining the + tabs, one joining the - tabs — that never cross.

Thread a needle with conductive stainless-steel thread. Stitch from the + tab of the battery holder to the + tab of the LED, looping 3–4 times through each tab hole for firm electrical contact. Knot tightly and trim the tail short — stray strands cause shorts.

With a fresh length of thread, stitch the - tab of the battery holder to the - tab of the LED the same way. Keep this line clear of the + line everywhere — if the two conductive paths touch, the circuit shorts and the LED won't light.

Slide a CR2032 coin cell into the holder, + side up, and switch it on. The LED lights — no separate resistor is needed, because the 3 V coin cell can't push enough current to harm it. If it stays dark, check the battery direction, loose knots, or threads touching.

Dab a little clear nail polish or fabric glue on each knot so it can't work loose or fray. Use the holder's switch to turn your LED on and off — your first wearable circuit is done.