The solution: using conductive thread, sew an 8x8 matrix of LEDs into collapsable umbrella, then add a MAX7219 LED Controller, a voltage converter and an arduino mini pro.
The result: a twinkling blue light show that can fold up to go with you virtually anywhere.
Step 1: Materials
Here's what you'll need (In the photo, clockwise from the umbrella):
- The umbrella: I found a clear "bubble" umbrella at Target for $17. This turned out to be absolutely perfect for this project.
- Arduino pro mini 328 5V/16MHz: Shown here with headers already attached. The Lilypad arduino would have also worked just fine. The pro mini and the Lilypad are so small partially because they exclude the USB circuitry necessary to talk to your computer, so something like the FTDI board below is also necessary with these boards to hook up the arduino to your co
- FTDI Basic Breakout: This small board hooks up to the arduino mini pro on one end & to a mini usb on the other end. You attach the FTDI board to the arduino to program it, but once programmed, you can leave it behind.
- MAX7219 LED display driver: This is a great little chip that takes care of multiplexing the LEDs. It 's drives a 64 led matrix. One major drawback is that the intensity is set for all LEDs; it doesn't allow setting different LEDs to different intensities. More info available here.
- Protoboard: I decided it would be easier to hook up the MAX7219, resistor & capacitors via a protoboard than directly on the umbrella. I ended up using a smaller one (1.75" x 1.75") than what is pictured here.
- LEDs: I used 64 clear blue "super bright" LEDs from SparkFun. I recommend using diffused rather than directional clear variety since your umbrella will be viewed from every direction.
- Heat shrink tube
- Headers: 90 degree headers used on the Arduino - it comes without headers attached. Also used to make battery removable.
- Wire: I used standard 22 AWG solid core wire. Using two colors is definitely helpful in keeping track of what's what.
- Conductive thread: I used the heavier 234/34 4ply thread & went through almost an entire 75 yard spool. This was my first time using conductive thread & I found it easy to use.
- Heavy sewing thread: I used some heavy sewing thread to attach the circuit boards to the umbrella. I tried using clear plastic thread (like thin fishing line) but it did not work well for me.
- Lithium Polymer Balance charger: this special charger is required for the battery I selected...
- 11.1V 900mAh Lithium Polymer battery: This is almost definitely overkill but I wanted something light & compact that would power the umbrella all night long.
- An old nylon strap & some velcro: I sewed these together to make a holster for the battery.
- Small metal rings: I soldered these to the ends of the wires coming off the MAX7219 board to make it easier to attach to the conductive thread. I happened across these amongst jewelry making supplies in the craft section of a big box store.
- zip ties: to help hold the battery in place
- Lilypad slide switch: to turn the umbrella on & off
- 1 resistor: 1kO (rset on MAX7219 circuit diagram)
- 2 capacitors: 10uF & 100nF
- An old car cigarette-lighter phone charger: this is a great trick I picked up in the comments right here on Instructables!. Crack the case off a car phone charger and you have a low cost 12V to 5V converter/regulator, suitable for powering the arduino.
- Sparkfun electret mic & op amp breakout board: to synchronize LEDs with music