Make:

• DIY Halloween - The Classics :: Fog Chiller
• BUG on Arduino action
• NoiseBridge: new SF hacker space
• Pedal powered tank
• BASE jumping with accelerometers
• Self-disinfecting toilet brush

Um... there's an easier way. Look for the numbers on your tubes (like 6c4 or whatever) They will be printed on the side. Look that number up on any of a number of web sites that list tube characteristics. Find the filament pins and voltage for your tubes. Wire the filaments to a (usually 6 volt) power supply and they'll glow and get warm on their own, rather like dim incandescent lightbulbs. Which, more or less, is what they are.

More detailed explanation, for the curious: The heat these filaments generate was used to excite the cathode (in some tube types the filament is the cathode) to emit electrons. These electrons are attracted to the plate, the component furthest from the cathode inside the tube, by the plate's positive charge. You control the flow of electrons to the plate with the various grids (rectifier tubes usually don't have any) between cathode and plate. Once you control the flow of electrons from cathode to plate, you can control a current as it flows through the tube from plate to cathode. So the filament was the engine that made the whole thing go.

If you do a bit of web searching you can find lots of sites on how to make the tubes do useful work, too. :)

-HH

There is, of course, a more traditional way to make tubes glow :-)

Thanks, but yes I do know how they work.
This was just a bit of fun, I didn't want to play around with heating and high voltages. They're glowing continuously on my bookshelf and I don't want them to burn out.

f(p)

Umm, also, the green glow would be hard to achieve with traditional methods :-)

ok, check out this cool TUBE ART! www.sparklemachine.com

Subscribe today, save 42% and get web access to MAKE free. MAKE Digital Edition is available only to subscribers.

$34.95 / 1 year
(4 Quarterly Issues)

Subscribe now