Recycle an old cell phone charger and wine bottle into a gel filled LED lamp.
Step 1: Parts List
- blue and red LEDs
- 220 Ohm and 100 Ohm resistors
- small toggle switch
- gel candle wax
I got the gel wax from Michaels for $32.23 with a 40% off coupon. There is enough wax to fill three 1.5L bottles.
With $11 worth of wax per bottle and $15 worth of electronics, this project cost about $26 all together. You could get the parts much cheaper online, but I wasn't feeling patient enough for that.
- glass drill bit
- squirt bottle
- soldering iron and solder
- wire cutters
- hot glue gun
- sticky tack
- a pot to melt the gel wax
- a food thermometer for the wax
Step 2: The LED Circuit
I used thin insulated wrapping wire from RadioShack to run power inside the bottle. The wrapping wire connects the cell phone charger to the ground and +5 V of the circuit shown in the picture. You can use a multimeter to find the ground and positive wires from the cell phone charger, or you can just touch the wires to the circuit and see if it works. The LEDs will only light up when it is connected correctly.
To find the correct resistor for each LED, we use:
The Forward Voltage and Max Current are given on the LED packaging, and we know our Supply Voltage is 5 Volts from the cell phone charger. When we plug in the known values, we can solve for the Resistance.
Find the Blue LED resistor
Supply Voltage = 5 V
Foward Voltage = 3.7 V
Current = 20 mA (0.020 A)
65 = Resistance
So, we need a 65 Ohm resistor to give the LED 20 mA of current. I used a 100 Ohm resistor I already had, so my blue LED is actually getting a little less than 20 mA.
Find the Red LED resistor
Supply Voltage = 5 V
Foward Voltage = 1.7 V (This is less than the Blue LED Foward Voltage)
Current = 20 mA (0.020 A)
165 = Resistance
We need a 165 Ohm resistor to give the red LED 20 mA of current. I used a 220 Ohm resistor I already had, so my red LED is also getting a little less than 20 mA.
Is this safe for the cell phone charger?
The cell phone charger is rated at 0.7 A max (same as 700 mA). Each of our LEDs is drawing less than 20 mA, so the entire circuit is drawing less than 40 mA. The 40 mA we are drawing is much less than the 700 mA the charger is rated for, so we are well within the specs of the charger... maybe we should add lots more LEDs : )
Step 3: Prepare the Bottle
You have to use a special glass drill bit to drill a hole in the wine bottle. You can find them at Lowes or Home Depot for about $7 each, or a 4 pack for $16. It will take 10 - 15 minutes to drill all the way through the bottle with these.
On my first try, I broke the bottle. After the hole went all the way through the bottle, the drill slipped forward and the drill chuck cracked the bottle. On my second try, I pushed a wine cork over the drill bit so it would act as a stopper and prevent the bottle from breaking again.
To drill the hole:
1. Put a cork over your glass drill bit so you don't break the bottle with the drill (see the picture)
2. Wrap the bottle in a towel and clamp it to a work table
3. Make sure you have a squirt bottle of water and a full drill battery
4. Start drilling straight down, and squirt the bottle with water every 5 - 10 seconds
5. Expect it to take 10 - 15 minutes to drill all the way through, don't use too much pressure
6. Use even less pressure when the hole is almost all the way through so you don't break the bottle
After the hole was drilled, I fed the phone charger cable through and held it in place with hot glue. The wrapping wire runs through the top of the bottle so it can be connected to the circuit that was built in the previous step.
Drill a hole in the bottom of the cork that is big enough for the toggle switch to fit in. The hole should go almost all the way through the cork. Then, turn the cork over and drill a small hole in the top so only the handle of the switch will poke through.
After you have the cork and bottle ready, finish connecting your LED circuit, and fit it into the cork. Let it hang outside the bottle so you can pour the wax in the next step.
Step 4: The Gel Wax
I followed the instructions on the bucket to prepare the gel wax. I had to heat mine up to 220 degrees to get it all melted, then I let it cool down to about 190 degrees before I poured it in the bottle. I poured at a lower temperature so there would be more bubbles in the end.
I put a layer of sticky tack over the hot glue I used for the power cord, in case the gel re-melted the hot glue. I didn't have any problems doing it this way. I started out using a funnel to pour the melted wax into the bottle, but the wax cooled and blocked the funnel before the bottle was filled. The wax is thick enough that you can pour it straight into the bottle as long as you take it slow.
I let the gel wax cool for about 10 - 15 minutes in the wine bottle, then I put the cork with the LEDs on the bottle. I turned the bottle upside down in a cup and let it cool some more, so more bubbles would be trapped toward the bottom of the bottle. I flipped the wine bottle back and forth a few times while it was cooling to help distribute all of the bubbles.
Step 5: The Finished Product
The gel wax and bubbles diffuse the red and blue light for a purple-ish glow.
Alternatives to the gel wax that I might try in the future could be:
- clear marbles or beads
- shattered pieces of tempered glass (like a car window)
- glass etchant to solution to fog the inside of the bottle