Wooden Christmas tree with colour-changing lights

Step 9 Prepare the LEDs and resistors

First, identify the anode and cathode on your LEDs. They have to be connected to the power supply the right way round or at best they won't work, and at worst they'll break.

Decide whether you're going to connect the resistors to the anode or cathode and stick to it, so you can identify the leads after you've bent the wires.

We decided to connect the resistors to the anode (the longer wire on our LEDs), so the resistors will be connected to +12v.

Pop a LED into a hole. Put the blade of a screwdriver at the base of the wire that won't have the resistor attached to it (near the plastic LED housing), and use another screwdriver to bend the wire over the first screwdriver blade. The idea is to get the bend in the wire a short distance away from the plastic housing of the LED, so it's less likely to snap off in the process.

Now wind one side of the resistor tightly around the other LED wire.

Do the screwdriver thing again with the wire on the resistor side of the LED, with the aim of getting the first LED wire and the other side of the resistor pointing in opposite directions.

Finally, snip off any excess wire after the coil of resistor wire.

Repeat for the other 30 LEDs, and the white LED(s) for the star.