Here is a quick and easy way to make a strand of RGB LEDs for a Christmas tree.
Step 1: Buy Some Color Changing RGB LEDs
My friend Jimmie
turned me on to some excellent color-changing LEDs. There are several kinds of RGB LEDs: the ones with four wires are meant to have their colors mixed by a circuit. The ones with two wires change on their own and can't be programmed. But they are fun and perfect for a project like this. I prefer the ones that change slowly, and Jimmie showed me that you can find these on eBay by searching for rgb slow color change
on eBay. They will take a week or more to arrive, which is cutting it close for this Christmas.
Step 2: Tools and Supplies
- A spool of green wire wrap (30 AWG) wire
- Wire wrap tool with stripper (or any wire strippers that can handle this wire)
- Wire cutters/snips
- Soldering iron
- Glue gun
- Panavise Jr. or helping hands
- 2 or 3 AA battery holder
Step 3: Prepare the Wire
Now you need to cut two wires to the lengths you want. One will be the positive side, the other will be the negative side. Strip one end of each wire and (optional, but recommended), tin the ends. Next, connect one wire to the positive lead of the battery holder and the other to the negative. Insert the batteries (3 rechargeable AAs worked best for me, 2 alkalines would probably work fine).
Now you have a live wire, so avoid shorting it out. Keeping it live while you assemble the strand solves two problems: you'll know immediately if you have the polarity reversed, and you'll also know immediately if you've damaged an LED.
Step 4: Create Contact Points Along the Wire
The next step is to use the wire stripper to create contact points along the way. You can do this by sliding the wire stripper into the wire and exposing a small amount (2mm or so) of wire. This makes the project go a lot quicker than if you were cutting lengths of wire between each LED.
Open a contact point on both the positive and negative strands at the same length along the strand. Remember that the power is still connected, so don't short the wires.
Step 5: Tuck the Exposed Wire Under the LED's Leads
Next, bend the leads of the LED as shown and tuck the bits of wire you exposed: positive to the long lead, negative to the short one. The LED will probably flicker on and off because the connection is not secured yet. Now you're ready to solder the LED in.
Step 6: Solder It
Put the LED into your helping hands or Panavise, and solder the lead to the exposed wire. See if you can keep it close to the start of the lead. Avoid shorting it out here (it's easy to accidentally touch the soldering iron tip across both leads) because it could damage the battery. Be especially careful with rechargeables. They should never be shorted out.
When you've completed the solder joint, clip the leads as close as you dare to the joints. Insulate the solder joints with some hot glue, move on to the next point along the strand and return to Step 4.
Step 7: Finish It
Keep going until you're happy. The more LEDs you use, the faster you'll wear out your batteries. I get 3-4 hours from 3 AA rechargeable batteries on a 45-LED strand. You can, of course, use some kind of wall wart, but don't give these LEDs too much juice or they will burn out.