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Being Creative: Tubes


STOP PRESS:I posted some of these photos on the MAKE Flickr pool and they blogged it!

As a kid I had a soft spot for an old valve radio that lived in the kitchen for many, many years. A little like this:
Something about the valves ("tubes" in the US) appealed to the Science Fiction fan in me I think. With their complex variety of rods, meshes, coils, heaters and shields they reminded me of miniature futuristic cities under glass domes. On a whim one day I bought three large tubes on eBay ($3.99!).
big tubes
I wasn't sure what I'd do with them, but when they arrived I arranged them in a pleasing little group on my book-case. This inspired me to mount them on a small wooden plinth. I don't know why, I just like the way they look. Mysterious.
I thought, "wouldn't it be cool if they glowed!" This set me off on a much more complicated project. I bought three more tubes on eBay, but much smaller and without the bakelite bases ($2.25!).
small tubes
Then I did a little research into driving LEDs with a 9V battery: put them in series with an appropriate resistor. I bought some LEDs, resistors and a small breadboarding base online from RadioShack. When they arrived I did some experiments and found that it basically worked, I could illuminate one of the tubes from beneath. The LEDs weren't particularly bright, around 20 mcd (20 millicandela, a 60W bulb is about 120 candela) so I visited a local RadioShack and picked up some brigher ones (600 mcd), a small toggle switch and a project box. I also got a 9V power supply, so I could plug my project in and forget about batteries. I visited a local surplus electronics store and got a 1k ohm potentiometer and knob. Then I got out my (cheap, crappy) "smoldering iron" and put it together.

In the project box
in the box

The final result
the final result

Glowing (maximum brightness)

¡Muy misterioso!
¡Muy misterioso!