Make a hackable LED ornament.

Step 4 Adding the resistors.

You can add the resistors inline in either of the two wires leading to each socket. I chose to put them inline with the red wires, and did it near the base of the ornament away from the socket end.

Cut the wire about 2" (50mm) from the end and strip and tin both ends. Cut one lead of the resistor down to about 3/16" (5mm) and tin it with solder. Keep the other end full length to give you something to hold onto as you solder the other end. I tend to clamp the wire into a little vice or clamp and then apply the tinned end of the resistor to the tinned end of the wire and reflow them together with the soldering iron. Once one end of the reistor is soldered to a wire you can crop, tin and solder the other end to the other part of the wire.

Once the resistor is soldered inline you can slip a short length of heatshrink sleeve over it and shrink it on with the careful use of a heatgun or other source of high heat.

The resistor will limit the current through the LED. 330 ohms are good for up to about 9V and 1000 ohms are good for up to about 18V.