I wanted a hat that lit up around the brim like one of those movie marquee lighting things. It took ages and ages, but I finally managed it! I also attached a pushbutton, so that when you push it, the led rotates faster. Yes the picture does look like multiple LEDs come on at once, but that's just because I am a lousy photographer. In reality, there is just one LED that rotates around the hat. I would like to acknowledge my dad for helping me with the circuit design.

Step 1: Things You Will Need.....

- 25 LEDs, I used MCDL-1860UWC-15C from Jameco Electronics but I think that most types of LEDs would work. I used 20 white LEDs and 5 blue LEDs.

- Some sort of hat, I used an old costume top hat but its really up to you. One thing to keep in mind though, is that the hat should be fairly stiff to be able to support the circuit board.

- Perf board, regular and protoboard

- 22 gauge stranded and unstranded wire

- Various soldering tools

- Black thread

- Header and pins for connecting the wires

- Three CD4017 Integrated Circuits

- One 555 timer

- 6.8k, 1k, and 4.7k resistors

-100k potentiometer

- Two 0.1uF ceramic capacitors

- 0.33uF and 10uF electrolytic capacitors

- One 74HCO8N Integrated Circuit

- 9 volt battery

- A SPST switch

Step 2: Cut Your Perfboard

To be able to sew LEDs onto your hat, you need to solder them onto some perfboard that you can sew to your hat. I cut pieces of perfboard that were four holes long and two holes wide. To cut perfboard, first score the board with a boxcutter on both sides, then snap the board apart. This method worked terribly, so if you know of a better way, please let me know!

Step 3: Cut Holes in Your Hat to Fit the LEDs

I wanted just the LEDs showing, not the yellow perfboard so I cut squares in my hat the size of my LEDs. You can use tailors chalk to mark where you want the LEDs to go; mine were about 2cm apart.

Step 4: Solder the Ground Wire to the Negative Side of the LEDs

Solder two wires to each of the negative leads of the LEDs through the perfboard so that there is a line of LEDs connected by wires. These wires are going to be between your holes in your hat so make them as long as the length between the holes. Also, solder one wire to each of the positive lead that is about 9cm long, depending on how big your hat is. The positive lead will go to the circuit in the middle of the hat and the negative leads will go to ground. Sorry the photo is so bad, I sewed the leds to the hat before taking a photo.

Step 5: Sewing the Leds to the Hat

Sew the leds to the hat with the four extra holes on both sides of the perfboard. This took me forever and the leds are not exactly straight, but that's just because I was impatient. Yeah, in the photo I forgot to take off the tailors chalk.....

Step 6: The Actual Circuit

Here's the schematic for the circuit. Solder all the components onto perfboard. Sorry the drawings kind of bad. Basically, the 555 timer sends a pulse to the decade counters that fire off their LEDs in sequence. The logic chip chains the three decade counters in order.

Step 7: Done!

Attach the positive led wires to the pin and headers. What you do next is really up to you, I attached the circuit to a piece of felt that I velcroed inside of the hat. This was to keep the circuit from shorting if my head started sweating. I also sewed a battery pocket on the inside of the hat to keep the battery from moving around. There are a lot of different ways you could modify this circuit, add more than one rotating LED or make it go faster or slower by changing the resistors. One thing that I thought would be cool would be to add a photoresistor to the circuit so that as night falls, the led would gradually get faster.