Introduction: The Dancing LED
Not so long ago (for the first time) I had a great time in Alun-alun Kidul Yogyakarta, Indonesia. There I saw many things that beautifully glow. From Tron-like small pedicab with bunch of LEDs strip on it, wearable glowing t-shirt, giant LED screen, and the likes. But none of them really grabbed my attention until I saw a flying thing that radiates green light while descending gently to kiss the ground. I took a closer look, and man.. this little piece of simple engineering was so amazing. It climbed like a V2 rocket and fell down like Soyuz descent module (but rather with style). Thanks to basic parabolic physics which made this possible. Alright, enough talk let's get wet.
Step 1: Gathering the Parts
- 1 x colored transparent sheet. (A4 size or letter).
Let’s try orange sheet first.
- Strong adhesive tape/paper tape.
- 3 x LR41 coin battery cell.
LR41 batteries can be interchanged with AG3, SR41, 392A, 392, 384, 192, 92A, GP192, G3, V3GA, V36, V36A, LR736, CX42, and SR41SW batteries.
- 50mm piece of cable.
- 5 different colors of vinyl sheets (yellow, red, white, green, orange); each 100x100mm.
- 1 x 5mm clear green LED (for the sake of this setup we'll use the green first, later you can experiment with any color). REMEMBER: This particular LED needs about 2.0 volt forward voltage in order to operate properly.
- 40mm of very rigid wire (about 1mm in diameter).
1 x (270x6x3mm) chopstick or stick made of wood, bamboo, or whatever you have laying around.
For the catapult system (thrower), you will also need the following parts :
- 2 x rubber bands.
- 1 x 200mm length and 7mm in diameter round-shaped rod/stick (again chopstick, bamboo stick or wood stick it’s up to you).
Step 2: Connecting the Electronics
The LR41 Alkaline coin have nominal voltage about 1.5V and typical capacity of 25-32mAh. While I have three batteries I connect them in series, adding up their voltage. So 3 x 1.5V = 4.5 volt. (REMEMBER: The capacity does not change when it connected in series).
Make sure you have connected the batteries properly in series. After you confidence with your connection then wrap the battery with paper tape forming battery ‘pellet’ and then connect the LED (don't forget to bend the legs).
Step 3: The Dancer
Time to work with the frame. Be careful when splitting the frame, it's only 3 mm thick. After splitting the frame now we have two fins platform. In this platform we will attach the colored transparent sheet with the help of some glue.
Step 4: Hooking Mechanism and the Catapult
Step 5: 3..2..1..0 And...
Now time to go off the ground. Make sure you're all set. Or you may want your dad to give GO/NO GO before launch. Please, do not aim to your mom, grandma, and other people. Do not aim to animal.
Anyway, after this glowing thing streaking up to the sky and hit its maximum speed and altitude, it will slowly starts to descend and begin its own dance. So enjoy.