Introduction: Cold Cathode Light Tube

About: I have a passion for tweaking things. Whether it be modding video game consoles, creating custom laser displays, or any creations with lights I love solving problems through unorthodox means. I like to go whe…

Time for a replacement or addition to home-lighting? As normal incandescents and compact fluorescents create rather uninteresting color tones , this guide has been created to create a unique and vivid method of lighting up your living areas.

Cold Cathodes, or Cold Cathode Fluorescent Lights (CCFLs) are very similar to a normal fluorescent tube used in lighting many offices and signs. These are different in that they do not require a large, high-voltage ballast, but they rather run "cold", with small inverters that amplify voltage to activate a paint coating inside of the tube. CCFLs are simple, cheap, and incredibly bright for their size. They have a tendency to make the air around them glow, which can be very beautiful and even entrancing.

This is perhaps the simplest instructable I have yet made. Parts are minimal, and putting everything together doesn't venture into complex wiring. For all the parts needed to complete three bars, I paid about $80. Using PVC parts, acrylic tubes, CCFLs, and a laptop power supply, we can create some superb lights.

Step 1: Supplies

Soldering Iron ($10)
A cheapy 15W iron from Radioshack.

0.022" Silver Rosin Core Solder ($4)
Becomes molten metal to make electrical connections. Silver helps it heat more easily and flow better, while rosin flux cleans your joints.

Heat-Shrink Tubing ($5-15)
A fair amount of heat-shrinking will be needed in shortening the CCFL wires. eBay has a ton of it for dirt cheap.

Hot-Glue Gun and Glue-Sticks ($5-20)
These will attach the caps to the acrylic pipe, as well as the 9v connectors.

9v Snap Connector ($1.50 each)
Connector available at Radioshack, intended for 9v batteries, we will use them as our "plug".

Electrical Tape ($4)
This tape goes on the underside of the exposed inverter, it prevents electrical shorts.

20 Gauge Speaker Wire - 25 feet ($3-10)
This will provide our extended power wires.

Laptop Power Supplies (~$13 each): They are cheap, regulated (which is normally very expensive), almost always provide 12v+, and are compact. It doesn't matter what brand you buy, we are cutting off the connector for raw wire. Be aware that on eBay some prices are very high, since laptop users whose power brick broke are desperate for a very specific model that matches their computer, it's o.k. to get off-label. Your voltage can be anywhere from 12v->16v. The inverters can take a range of power, pretty much anything under 16v and higher than 10v is acceptable. As far as the power supply rating, 60 Watts is pretty common, and should be plenty for four tubes (I have been running twelve CCFLs inside three tubes from a 64W for a couple months, though it gets very hot). The average single 12 inch CCFL pushes 12v DC @ 400mAh, or around 4.8 Watts per CCFL. To calculate Wattage, simply multiply Volts times Amps.

I prefer getting Fujitsu laptop power supplies, simply because they are compact and they've served me well in the past. Another very acceptable supply are those for large LCD computer monitors (21"+). I just searched "laptop fujitsu 16v 4A" on eBay and bought a supply for $13 including shipping.

Cold Cathode Fluorescent Lights ($6 per 2x 12" Tube Kit)
You have many options here. CCFLs come in various sizes, ranging from 4" -> 36". The largest commonly available colored CCFL is 20", and those generally run about $15-20 per CCFL, and require their own special inverter. For the purposes of this guide, I will be using the most common CCFL type: 12" colored bars. The most common colors are Red, Green, Blue, White, and UV, and I don't suggest unusual colors like Yellow, Orange, or Purple, as they never shine the colors that website photos suggest.

There is a difference between purchasing CCFLs and a CCFL kit. A kit contain two tubes, an inverter, power cords, and a switch, and are generally the best purchase when getting new lights, while just CCFLs means only replacement tubes.

Here are some stores for purchasing CCFLs that I recommend: My favorite place to buy CCFLs, they are a computer website with excellent prices and selection. I'm only listing them because they sell 20" CCFLs which can be hard to find, then again, each costs $20, which can be too expensive, especially when you can get four 12" tubes (48" worth of light) for $12 elsewhere. They have the biggest selection of CCFLs I've ever found. They have some very unusual tubes, such as tubes with micro-inverters built into them, focused direction tubes, along with uncommon sizes.

3x Acrylic Pipes -- 57" long, 1 1/4" wide, 1/8" thick  (~$12 per pipe)
Whenever I need high quality plastics, I always purchase from TAP Plastics (Plastic Rods on the Left). They sell a huge range of acrylic and polycarbonate materials, though for this guide, we are only using round acrylic tubes.

1 1/4" diameter, 6' long, 1/8" wall pipes are $11.65 each. Watch out for shipping though, I had my pipes cut to 57 inches for some working room and to avoid a $10 oversize shipping charge for anything 6' or longer, cuts are free.

We need a very specific diameter of acrylic, since we want our CCFLs to fit snugly. The widest point of a CCFL (diagonally) is 0.8". CCFLs including their end-cubes are 12.25" long. Subtracting the wall thickness is 1 1/4" - 1/8" = 1.125". This gives our CCFL 0.325" to fit in with, which is perfect since we need some space for wiring. Also take into account the size of the CCFL inverters (shown later), though for me they fit snugly within this 1 1/4" pipe.

Hacksaw ($10)
To properly adjust the length of the Acrylic pipe.

PVC Ends ~$8-10
6x Caps: These go onto the ends of the Acrylic pipe.


6x Plugs: Though I used caps which go over the PVC pipe which I find easier, you could just as easily use a PVC plug that goes into the pipe to make it more clean/compact. You will need some extra length on your acrylic pipe to make up the difference however.

Step 2: Preparations

Test if the CCFLs Turn On
Obtain a computer, look inside for a molex power connector (rectangle with four pins, with a yellow, a red, and two black wires). Connect the inverter to the molex, the CCFLs to the inverter, and flick the red power switch on the thin metal plate.

Test all your tubes and inverters, all of the inverters are interchangeable.

Removing Inverter Cases
The blue rectangular boxes are the power inverters. They convert 12v DC to around 700v AC. We need to pop off the protective hard cases, because they are too large to fit into the tube. Take any thin object, a screwdriver, a paper-clip, a knife, and pry off the bottom plate from the four dents on the sides.

Step 3: Measurements and Cutting Wires

In one quick step we will measure the length our acrylic tube should be, and how long our two speaker/power wires need to be.

Measuring Proper Acrylic Length
Connect two CCFLs to each inverter, and lay them on the ground next to the acrylic tube with the inverter in-between its two CCFLs. This way, we will know the practical, full length  our acrylic tube needs to be. Calculate in if you are using caps or plugs for your final piece, and cut accordingly with your hacksaw.

Measuring Speaker Wire Lengths
With your four tubes and inverters next to the pipe, take some speaker wire, and measure from each inverter to about a foot past the pipe. It's fine to have plenty of spare wire, we will just snip it off later.

Shortening CCFL Insulated Wires
The white insulated wires that are attached to each CCFL are about a foot long. While we could just squish the CCFLs into the acrylic tube, when the white wires are crunched down and crossed together their power fluctuates, called leakage. We need to shorten them, which will make them fit more compactly, and not have issues with brightness, flickering, or simply turning off.

***Special Note Before Cutting and Stripping Wires****
The two wires coming from each CCFL are not labeled, there isn't any easy way to determine which is positive or negative. The simple answer, is to take a sharpie, and mark a single one of the wires with black marks. I've attached a picture explaining. This way, we can simply cut them both, and know the marked wire is the same.

Please be extremely careful to not pull on the white wires on the CCFL side. They can easily snap/tear out of CCFL itself, and then you have nothing to solder to. Just take it slow and gentle when stripping the white wires.

Staggering Cuts
This is a trick that not only makes for cleaner wiring, but prevents the possibility of the wires shorting out, or in the case of dealing with high-voltage, greatly lowers the amount of leakage at the weak points where we cut. When you cut your wires, simply make one wire cut an an inch or two long than the other. Do the reverse for the opposite, connector end. Again, look at the images for reference. When soldered, they will match perfectly, with the cuts around a half-inch apart.

Wire Lengths
The inverter has both its connectors on only one side. Thus, one CCFL wire will be immediately at the connectors, and the other must travel the length of the inverter. Make sure you take this into account when cutting, one CCFL must have its insulating wires longer to go along the inverter.

See the images below for examples of each.

Step 4: Soldering, Sheathing, and Taping

It's time to solder our insulated wires back together. This is extremely basic soldering, just reconnect the staggered wires. I strongly recommend using shrink-wrapping, since it will provide some electrical insulation and strength to the bond. If this is not practical, you can always wrap the wires with a good deal of electrical tape.

Test each of your tubes in an inverter once they have had their wires re-soldered.

Speaker Wire Soldering
Also solder your speaker wires to the red/black cable that connects the molex to the inverter. Almost all speaker wires have markings along a single wire, whether it is text, "+" symbols, or a black line. Just make sure that you know which marking goes to the red (positive) and black (negative) or the inverter power connector.

Taping the Inverters
Apply electrical tape to the entire underside of the inverters. There is some real danger to having the inverters exposed, I at one point had an electrical short that produced a great deal of smoke from a positive pin on the AC underside of the inverter, jumping into the negative DC of the speaker wire. Applying electrical tape to the bottom connections prevents that.

To put it simply, cover the bottom of the inverters twice with electrical tape. Don't wrap the entire inverter in tape since they wont fit into the tube and is unnecessary.

Step 5: Packing in the CCFLs and Drilling Caps/Plugs

Connect everything together, the two CCFLs into their inverter, and a speaker/power wire into the inverter.

Both the power wires will be dropped down into the acrylic tube first. Then insert the CCFLs and their inverters into the tube, pushing/pulling/jiggling the power wires as you pack everything in. It will take some real monkey-fisting to get everything inside the tube with both speaker/power wires hanging out of the acrylic pipe, but you'll eventually get it. 

Caps/Plugs and 9v Connectors
The speaker/power wires need a way to connector to our laptop power supply. I've found that 9v connectors work very well, they are simple to solder, are electrically protected, and are very sturdy.

With your power drill, drill some small, 1/8 holes into the top of the cap that the red and black wires can go through. The 9v connector will be glued to the side of the cap, if you are using a plug, it will be very compact and glued on the flat area.

Use a hot-glue gun to attach the 9v connector to the cap/plug. Then cut the black/red wires to a short length, maybe 4-5 inches.

Step 6: Soldering Caps/Plugs, Laptop Power, and 9v Connectors

With the 9v connector glued to your cap/plug, solder the 9v connector to their matching color wires. Red-> Red; Black->Black.

At this point leave the caps unglued to the acrylic, we are going to prepare the laptop power supply to connect to the 9v connectors.

Laptop Power Connectors
Start by snipping off the barrel plug on the end. There are two wires inside, one a positive, one a negative. Most likely, one should be marked as a negative, whether this is with the "-" symbol, colored black (with the other wire being red, yellow, or white), or some form of labeling. If you are unlucky, you can just use a multi-meter or try to turn on a 5mm LED, which will only turn on for correct polarity (and will also rapidly burn out at 16v).

Testing polarity (The simpler and dangerous method)
If you choose, you can use a multimeter, I like to keep projects simple. Strip the wires that are inside the laptop power cable, plug it into the wall, and tap them to the 9v connector wires on a PVC cap for under a second, holding them too long may burn out the inverter if the polarity is wrong. Whichever direction turns the CCFLs on is correct, they should instantly light up if the polarity is correct. Just know or mark which wire went to the hexagon or circle on the 9v connector.

More 9v Connectors
I have three CCFL light tubes I am making. I thus attached three 9v connectors to my laptop power cable. For these connectors, the polarity wires are reversed. A circle is now going into a hexagon, and vice-versa. You can either follow with your eyes the path the electricity is taking to get to the power supply, or simply twist the 9v connector wires to those of the laptop cord, and do another quick tap. When you've got it figured out, just solder the three 9v connectors into bundles on the laptop power wire. They should all be interchangeable with all of the Light Tubes.

Step 7: Finishing Touches

If everything works, you can now stick on the caps and glue everything down. You can lengthen your 9v laptop power wires if you want to arrange them around the room. There are various options you can apply these tubes to, all three could be combined into a single light-stand, lay them behind/under/inside furniture, or hung from the ceiling. I mounted mine to the wall with 1 3/4" electrical U-Clamps bought from Lowes. Though not included in this guide, I also made a 14v battery pack out of AA batteries to use them without being stuck to a power outlet. (Really cool when in the mountains at night.)

You're now in possession of some incredibly beautiful and bright lights, the possibilities are endless.

If you have any suggestions, compliments, confessions of love, criticisms, or cool examples of what you've done with this guide, feel free to leave a comment.