This being my first Instructable I wanted to create something simple but still interesting. I stumbled upon these "Holiday 2008" Coke bottles and my project was born. This project also uses recycled parts. This would make a nice project to share with the kids and teach basic principles of electricity. I hope you enjoy and Happy Holidays!
Step 1: Getting Started
OK once you've enjoyed your ice cold bottle of coke, wash it out with warm water and let it dry. Now round up some 3/4 inch pvc pipe from your plumbing bucket and make sure it will fit snug into the mouth of the bottle. Cut the end of it square, then push the freshly cut end all the way into the bottle until it touches bottom. Cut the pipe flush with the top of the bottle, and pull it back out. Use some fine sandpaper to smooth the ends. If your piece of pipe has writing on it sand it off too. You want the pipe pretty and white for it's reflective qualities. Next using a 1/8 drill bit or file make a small notch in one end of the tube. This will be the bottom.
Step 2: Solder the Bulb
I originally intended to use an LED for this project due to the low current drain and long life, but the red LED's I tried washed out the lettering on the bottle, and white LED's use too much voltage for 2 AA batteries, so I opted for a 2 AA flashlight bulb like the ones found in Mini Mag flashlights. Solder 2 wires to the leads of the bulb taking care not to bend or damage the leads and crack the bulb. One wire is a 22 or so guage solid copper strand. Use about 6" so you'll have plenty to work with. This supports the bulb once assembled. The other is a smaller stranded wire. Use small wire to save space. I used a piece of insulation cut from a solid wire to make an insulator for the solder joint on the small stranded wire. This should keep it out of trouble. Bend the solid wire to form a hook. Now strip a section of the solid copper wire to make a bare wire about 6" long. Bend the wire about 2 inches from the end around a AA battery to form a loop. Tighten the loop a little to make it fit inside the pvc tube. Solder the loop so it stays, then use a small screwdriver to bend the rest of the short section to form a spring. Bend the long section 90 degrees up as shown in picture. Solder the small stranded wire from the bulb to the copper spring, making sure the bulb will reach past the spring.
Step 3: Get Creative!
Now grab a piece of paper from your printer and cut it so you end up with a 4" x 8 1/2" strip of paper. Draw two batteries along the short edge with the polarity marked + and - just like you see in a flashlight. Roll the paper around a pencil so that your drawing is inside the tube. This will be your battery holder. Now the tricky part. Slide the solid bulb support wire and spring wire into the notched end of the tube with the long ends sticking up past the top. Make sure the wires going up through the tube are right next to the notch you made. Go ahead and push the spring wire on up in the tube a little, making the smaller bulb wire snug, but leave the bulb down past the bottom. Using the end sticking out the top of the tube, turn the bulb wire so that the bulb is inline with the tube, and insert the whole thing, bulb first, into the mouth of the Coke bottle. Once inside, you can look through the bottom and hook the bulb wire into the notch made in the tube, so that the bulb is outside the tube and the wires are running neatly up the tube. Push the tube all the way into the bottle.
Step 4: Finishing Up
Now take your paper roll and roll it up tight, remebering which end is + and slip it into the tube with all the wires running between, and the + side up. Gently push the bare copper spring down to the bottom of the tube while moving the paper into the tube until it's bottomed out. Using a pencil with an eraser, unwind the paper roll inside the tube until it's big enough for 2 AA batteries to slide in and out, letting the bottom battery negative contact the copper spring at the bottom. Once the batteries slide in and out ok, leave the batteries in the tube, positive ends up. Once everything is against the bottom of the bottle and the bulb wires are in the notch, cut the bare copper wire flush with the tube. Now cut the other solid wire about 1 1/2 inches past the tube and strip it 1/2 inch from the end. Using needle nose pliers wind it around a 1/8 inch drill bit or small screwdriver to make a small coil. Continue making bigger coils past the insulation until it fits into the tube, and contacts the top battery. The bulb should light up! You may want to turn the tube inside the bottle slightly to adjust where the light is. Now if you adjust the coil carefully, it will turn off while the lid is loose, and come on when the lid is tight. Put the lid on your bottle, go into a dark room, and show it off!