Crookes Tube

Foil Leyden Jar Helps Bring Crookes Tube To Life

It might be too soon to consider the innards of the old CRT monitor at the back of your closet to be something worth putting on display in your home or workshop. For that curio cabinet-worthy appeal, you need to look a bit further back. Say, about 150 years. Yes, that’ll do. A Crookes tube, the original electron beam-forming vacuum tube of glass, invented by Sir William Crookes et al. in the late 19th century, is what you need.

And a Crookes tube is what [Markus Bindhammer] found on AliExpress one day. He felt that piece of historic lab equipment was asking to be put on display in proper fashion. So he set to work crafting a wooden stand for it out of a repurposed candlestick, a nice piece of scrap oak, and some brass feet giving it that antique mad-scientist feel.

After connecting a high voltage generator and switch, the Crookes tube should have been all set, but nothing happened when it was powered up. It turned out that a capacitance issue was preventing the tube from springing to life. Wrapping the cathode end of the tube in aluminum foil, [Markus] formed what is effectively a Leyden jar, and that was the trick that kicked things into action.

As of this writing, there are no longer any Crookes tubes that we could find on AliExpress, so you’ll have to look elsewhere if you’re interested in showing off your own 19th century electron-streaming experiment. Check out the Crookes Radiometer for some more of Sir Williams Crookes’s science inside blown glass.

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Retrotechtacular: Cathode Ray Tube (CRT) Manufacturing

This week we return to the grainy and un-color-corrected goodness that is synonymous with ancient video reels. [CNK] sent in a tip to a set of videos showing how Cathode Ray Tubes are manufactured on a massive scale. You’ll want to watch the pair of clips embedded below which total about 18 minutes. But there’s also some background to be found at this post from the Obsolete Technology Telley Web Museum.

The video presentation starts off with a brief overview of the way a color CRT works. It then moves to a factory tour, carefully showing each step in the process. The footage was shot in the 1960’s and because of that we catch a glimpse of some vintage equipment, like that used to measure the curvature of the CRT glass. You may be thinking that the world of CRT is in the past, but not so. We think there may even been a coming fad of producing them in your home lab.

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Homemade Cathode Ray Tubes


[dylan] tipped us to [Nyle Steiner] who’s been making his own cathode ray tubes Not satisified with that, he made an even smaller one[youtube] and he built an oscilloscope[youtube].

Once I noticed that he’s an amateur radio operator, I started digging around his site. His propane lawnmower is a great idea, his diy photocell makes me think of mr. wizard. If you dig tube amps, you’ll definitely be interested in his vaccum tube building experiments.

[Got a cool circuit? Lay it out on a PCB and enter the Design Challenge.]