Introduction: Cold Cathode Night Light

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This project shows how to flip ordinary items from a home recycling bin into a tabletop nightlight. A miniature, cold cathode fluorescent lamp (CCFL) is powered by a 5 VDC inverter circuit that produces high voltage (HV) AC. The light illuminates a paper lampshade with a colorful design.

Use caution with the inverter circuit. The output can produce an unpleasant burn!

Step 1: Prep Lamp Holder

I started the project with a cool white, CCFL (10.1 cm X 0.3 cm). These lamps can be salvaged from LCD screens of vintage portable computers. Don’t own a legacy laptop? No worries; a 6" (15.5 cm) fluorescent lamp (Model: F4T5) works with minor mods to the lamp holder; or they are available online.

Drill a hole through two, plastic toothpaste caps large enough for a #8-32, round head machine screw. (The screw length depends on the type of caps you're using.) Drill a hole of equal diameter through each plastic bottle cap from a soft drink. Drill the same diameter hole though the tips of two ice cream sticks.

Step 2: Assemble Lamp Holder

Assemble holders by inserting a rubber grommet into the top of each toothpaste cap. Place a ring connecting terminal on a machine screw before securing toothpaste, bottle cap and one ice cream stick with a nut. The screw heads are electrical contacts for the CCFL. Toothpaste cap and grommet must be positioned inside of each bottle cap as shown.

Step 3: Make Lampshade Frame

Roll a clear plastic sheet cut from a take-out food container into a tube. Use a rubber band to hold the shape of the tube. Trim tube with scissors as needed so it fits snugly inside of each cap. Tube length should extend slightly beyond lamp length. Use clear tape to secure seam.

Step 4: Assemble Lamp Frame

Cut lamp contact screws to an appropriate length, then cap tube ends with lamp holders after press fitting lamp into grommets. Make sure screw heads contact wire leads of lamp. Use a rubber band to hold the assembly together until ready to mount on base.

Step 5: Lamp Base Construction

Use the bottom of a discarded, bank checkbook box to make a rectangular base slightly larger than the length and width of your lamp frame. Place the base lengthwise on a flat surface. Using a hobby knife, cut out two slots from each end to accommodate ice cream stick supports. For better support, use mini corner braces and machine screws as shown to mount sticks on base.

Step 6: Mounting Inverter Circuit & Attach Feet

I repurposed this spunky, DC-AC inverter circuit from a broken 3” plasma globe display to power the CCFL. If you can salvage an inverter circuit from a computer LCD, that's another option.

DIY warriors can follow this dated (but well documented) link to build their own “super simple inverter.” Mount circuit on base using two, equal-length stand-offs made with small cardboard tubes from rolls for dog litter bags.

Glue toothpaste caps on each corner of base for feet.

Step 7: Sketch Lampshade Design

I sketched several rough lampshade designs on scrap paper using colored highlighters. For the final design, I needed thin paper that wouldn't block the light; so I used a blank page of onionskin paper cut from an old Verizon telephone book.

Step 8: Lamp Test

Attach insulated HV wire to one side of assembly with ring connector; ground other side of assembly. Mount optional plastic wire guides at the midpoint of each stick. Attach DC input jack to base with Goop or similar adhesive. Use a phone charger and USB cable for power.

If needed, remove lamp from assembly and wrap ends with small strips of blue painter's tape to ensure a better fit in each grommet. Reassemble end caps and power up inverter to test lamp.

Step 9: Final Assembly & Troubleshooting Checklist

Insert colored lamp shade into plastic tube, recap ends, and switch on lamp.

There’s not much to go wrong with this project; but if the lamp won’t fire:

  • · confirm a snappy spark from the inverter output using an insulated (!) screwdriver;
  • · check screw heads to confirm they touch ends of the CCFT;
  • · swap out the switching transistor of the inverter if it overheats during extended operation and replace with a sinked 2N3055, which should work.