My 5 year old granddaughter wanted a night light for her bedroom. Recently I have been building things with a Steampunk look, so this give me an excuse to build another project. This project uses some recycled materials that can be found at your local thrift store. Vacuum tubes can be found on Ebay and other components such as resistors and leds can be purchased at Mouser, Digikey or Electronic Goldmine.
Step 1: Find a Box
I found a suitable box at a local Thrift store and paid about a dollar for it. You can re-stain and finish it if needed.
Step 2: Glowing Vacuum Tubes
I used surface mount white leds to illuminate the vacuum tubes. Even standard T1 or T1-1/2 leds would work too. I cemented the surface mount leds with super glue. Standard size leds could be hot-melt glued on. I attached #30 enameled wire to the surface mount leds and super glued the led to the tube. When doing this, note the polarity of the led and mark a stripe on the wire with a sharpie. Then later, when connecting the leds, you will know the polarity. You can find the vacuum tubes on Ebay.
Step 3: Plan Your Layout
Layout the gears and tubes on the top of the box. Mark with a fine sharpie and drill and tap holes for the screws. I used #4 hex head allen machine screws to fasten the gears. Holes will need to be drilled for the tubes. The gears were purchased from a local arts and craft store. They are part of the Tim Holtz collection.
Step 4: Attach the Tubes
Series connect the leds and hold down the wire end to the top of the box with hot-melt glue. Drill holes for the tubes in the top of the box and secure down with hot-melt glue.
Step 5: Powering the Leds
Each led takes 3.13 volts. Total voltage drop is 9.39 volts. To power the leds, a wall-wort power supply and a series connected resistor is used. If a 12 volt wal-wort is used, it may peak to 16 volts at low current, as it did in mine. This leaves about 7 volts across the series resistor. I wanted to drive the leds to about 10 to 15 milliamps. Selecting a 560 ohm, 2 watt resistor ran the leds at 12 milliamps. Just right.
Current in amps = Voltage / Resistance in ohms.
I selected a 1 watt resistor to handle the load. Actual power across the resistor is Current X Volts or in this case 7 X .012 = 1/2 watt. Always run your resistor at about half its rating to be safe. The 1 watt resistor was just right.
I mounted the resistor on some perf board and added a 2.1mm power plug socket. Bore an oversized hole in the case to accept the plug from the wal-wort.
Step 6: Top View
#4 Allen Socket head screws hold down the gears on the box. I tapped the hardwood box with a #4 tap. On softer wood, you can add a drop of wood glue to the screw thread to help hold it down. You may need to open up the holes in the gears to allow the screw to fit.
Step 7: Conclusion
You can use other items besides vacuum tubes to illuminate. Such as toys, gem crystals, small light bulbs or test tubes filled with plastic chips. One of my next art projects is a 1000 watt mercury bulb turned into a night light.