The joke goes like this: if you want to make something Steampunk, add gears; if you want to make it CRASHspace, add LEDs.

If you know me, you know that I wear bandanas always. I have several dozen (seriously, see the picture in step 1). When it comes time for events like Two Bit Circus' STEAM Carnival, I like wearing something that's geeked out, and in this instance (and because I had a bunch left over from a party), I decided to use some flashing RGB LEDs to light up one of my bandanas.

To put this project in context:

There are a lot of other fun ways to incorporate LEDs into a wearable project, microcontrollers (like a Gemma, Trinket, or LilyTiny) can give you more control without adding a lot of size, and there are LEDs that are specifically designed for sewing. (There are 10 links in that sentence, several by CRASHers, and they're all worth checking out!)

This project aims to show a very simple circuit, uses some of the most easily attainable materials, including my super slim, 3D-printable, sewable battery holder, and requires only basic soldering skills.

And lights go on your head! That's a fun factor if ever I heard one.

Check out the last step for a video of it in action!

Step 1: Materials

- A Bandana, Headband, or at least 1/4 yard of fabric to make one (there are manymany options here)

- LEDs (see step 4 about types)

- Coin Cell Battery Holder, or access to a 3d printer to print one

- Silicone-Covered Wire (or conductive thread if you're going solderless)

- Needle and Thread

- Wire cutters

- Black Sharpie

- Soldering iron (and solder)

- Third hand tool (helpful)

- Sewing Machine and Iron if you're making your bandana or headband (optional)

Step 2: Fabric for Your Head

Here are some quick and dirty instructions for making a bandana or headband. As with any sewing project, the iron is your friend. Measurements are super variable; you can change them quite a bit from what I say here and still get a good result.

You can buy a regular paisley bandana, or you can go to a fabric store and find a much wider variety of patterns and colors. Bandanas vary in size, but a good average for an adult head is somewhere in the vicinity of 15-18" square. For kids, you can go a few inches smaller. A "fat quarter" of fabric is just enough for a bandana (trim it to a square). Half a yard of 44" fabric will give you enough for two squares. Alternatively, you can get a quarter yard and make a long headband.

For bandanas:

You don't have to sew a hem on your bandana (not all of mine have them; sometimes a raw edge is fun), but it will keep the edges from fraying. You can do this by hand if you don't have access to a sewing machine; it'll just take a bit longer.

Start in one corner of a square of fabric and sew with the edge folded over. Just before you get to the corner, stop and fold it in, then continue to the end and (if you're using a sewing machine) sink your needle at the corner to turn.

Repeat!

Take your lovely sewn square, double it over into a triangle, and tie it around your head with a double knot (or measure and sew like I did in the picture) to get the size just right for your noggin.

Tada!

For headbands:

Starting with a quarter yard of 44" fabric, I cut a strip about 8" wide. You can adjust this, of course: measure how wide you want the headband, double that number and add an inch for the seam.

Fold the strip of fabric in half, longways, with the "right sides" together. Then just sew the open long side, and turn it right-side out. Again, you can do this by hand, it just takes a little longer. For the ends, you can leave them with a few inches still folded inside, and either sew them up, or iron them, which will usually keep it in place without a seam. Wrap the fabric around your head and tie or sew it at the base.

There you go, simple head coverings! Now they just need electricity.

Step 3: Print a Battery Holder

I used coin cell batteries to power this. You can buy battery holders, or you can use my 3d model to print your own (quicker, cheaper, thinner) sewable ones. When I wear a light up bandana using these pressed against my head, I don't even feel them.

I've attached the STL for my coin cell battery holder. It's a modification of this design on Thingiverse. Print it up, and follow the photos for how to attach wires. It's easiest to use solid wire, but go ahead and experiment. Using red and black for positive and negative makes your life easier when you're soldering.

2032-coincell-sewable.stl
Download View in 3D

Step 4: About the LEDs

The LEDs I got came from AllElectronics, but can also be found at Adafruit, Sparkfun, and other places. For the edge of my bandana, I powered seven LEDs from a single 2023 coin cell battery, which should keep you going for at least an all-day event.

(I have plans to do 3d-printable battery cases for other types of batteries, including rechargeable coin cells. Keep an eye out for that upcoming 'ible.)

Here are some other sources of LEDs that can be useful. There are, of course, great specially-made sewable LEDs, and you can attach them to a Gemma or other microcontroller for more fun. Also... Neopixels. Neeeeeopixels. For this simple project, I decided to use the regular 5mm pretty blinking ones I had on hand.

The LEDs are soldered together in parallel, using silicone-covered wire. If you haven't discovered this stuff yet, you owe it to yourself to try it. A lot of e-textile projects use conductive thread (I prefer the shiny type to the fuzzy), which can be great, but isn't as reliable over the long term. One of the chief advantages it has over regular coated wire is that it's more flexible and can be sewn in without adding a lot of weight and bulk. Fine gauge silicone-covered wire is soft, and while it does have a touch more bulk than conductive thread, it's also more reliable for a connection, and you don't have to worry about accidental shorts all over the circuit. So for my e-textile projects, you're likely to find silicone-covered wire. Adafruit has many colors here if you'd like to get some.

If you want to use conductive thread (if you don't have access to a soldering iron), here is a nice instructable about sewing electrical elements to fabric. Making a loop out of the leads is a really good idea, and she highlights getting a good solid connection with the thread.

Step 5: Assembling the Circuit

As is my modus operandi, I used a black sharpie to mark the negative leg of each LED (the shorter of the two) because it makes it easier to identify later, and then bent the legs out to the sides for soldering.

I started at the edge, laying out the LEDs and measuring. I figured out that seven LEDs spread along the back corner would do well with about two inches of wire between them. I cut and stripped twelve two-inch pieces.

The process: we're putting the LEDs in parallel, so solder all of the negative leads (those marked black) together in a chain, and then do the same with the positive leads.

(If you don't have access to a soldering iron, or aren't allowed to use super hot tools, you can just twist the wires and LED legs, but be aware that it won't be as secure.)

The first LED only needs a single wire per leg, as it's at the end of the chain. Twist the end of a length of silicone wire around the LED's negative leg (marked black), near the bend. A third hand tool is helpful here for keeping things immobile. Solder the wire, trim the excess, and move on to the next.

Each LED in the chain after the first will have two wires soldered to each leg. You can twist them up and solder them at the same time. Grab the other end of the previous LED's wire and the end of a fresh one, then twist both to the negative leg of the next LED, solder, and clip as you did for the first. Same thing on down the line. At the other end of the chain, you'll solder together the LED leg, the previous LED's wire, and the wire going to the battery holder.

Note: you can add a switch to your circuit if you like, or you can follow the instructions in Step 9.

Step 6: Test (Lookit the Pretty Lights)

It's a good idea to test as you're assembling the circuit in the previous step. You'll definitely want to test when you have it all wired up, and before you insulate it. After the next step, it's harder to go back and fix loose connections.

Step 7: Insulating

Because this project gets around, and has the potential for getting wet (either in the rain or the wash), I used hot glue as a stabilizer and insulator at the base of the LEDs where all of the wires are soldered. Globby glob glob.

Step 8: Onto the Fabric

When your wires are all soldered together, you can sew them on to the back side of the bandana, using a similar colored thread. The battery pack I've included has holes for sewing it on. I placed the battery holder at a spot where it rests next to my head. It's small enough that you can't feel or see it, and being slightly compressed between the fabric and your head means that your connection will be more secure.

You don't necessarily need to sew all four holes of the battery holder base (opposite corners work fine), but you do want to sew both holes of the cap, or your battery connection might not be all that reliable.

Note: this does mean that in order to change the battery, you'll need to cut the thread on one side of the cap and resew it. That inconvenience will be fixed in an upcoming version of the battery case, but this version does connect the battery just fine.

Step 9: Switch

As I said before, you can wire a switch into your circuit if you like (I haven't yet designed a version of the battery holder that includes a switch), or you can go simple and slide a piece of heavy paper under the battery, which is how I usually do it. (This is why there's an opening at the end there)