It’s funny how sometimes things you think are bad turn out to be good in retrospect. Like many of us, I was fascinated by science of all kinds when I was young. As I got older, I got a little more focused, but that will come later. When you lived in a small town, there weren’t many science and technology books lately, so you tended to read the same ones over and over again. One day my library acquired a copy of the relatively recent book “The Amateur Scientist” which was a collection [C. L. Stong’s] Scientific American column of the same name. [Stong] he was an electrical engineer with broad interests and those columns were amazing. The book only contained snapshots of the projects, but they were amazing. Of course, the magazine had even more projects, most of which were beyond my budget and even more beyond my capabilities at the time.
If you clicked on the links, you probably went down a very deep rabbit hole, so… welcome back. The book was published in 1960, but the projects were mostly from the 1950s. These 57 projects ranged from building a telescope – the original subject of the column earlier [Stong] took it over — to use the bathtub to study the aerodynamics of model airplanes.
X-rays
However, there were two projects that caught my eye and – fortunately for me – I never even came close to finishing. One was for building an X-ray machine. His name was amateur [Harry Simmons] he described his setup and complained that in 23 years he had never met anyone else who had X-rays as a hobby. Surprisingly, at the time, there was no problem with the magazine publishing his home address.
You needed a few things. The Oudin coil, something like a Tesla coil in an autotransformer configuration, generated the necessary high voltage. It was actually the Ouidn coil that started the whole thing. [Harry] he used it to power UV light to test minerals for fluorescence. Out of idle curiosity, he replaced the UV bulb with a radio tube 01. These old tubes had a magnesium coating – a getter – that absorbs any stray gas left inside the tube.
The tube lit up [Harry’s] hand and it reminded him of what an old X-ray tube looked like filled with gas. He grabbed some film and could imagine the screws embedded in the block of wood.
However, 01 tubes were hard to come by even then. So [Harry]who is what we would now call a hacker, took the obvious step of having a local glassmaker create custom tubes to his specifications.
Since I lived in a place where the library barely published books after 1959, it’s no surprise that I didn’t have access to 01 tubes or glass blowers. It wasn’t even clear if he was evacuating the tubs or if a glassblower was doing it for him, but the tube contained less than 0.0001 millimeters of mercury.
Why did I care as a kid? I don’t know. Anyway, why do I care now? I would build one today if I had the time. We’ve seen more than one x-ray tube home project so it’s doable. But today, I’m probably able to safely control high voltage, high vacuum, and shield myself from x-rays. Probably. Then again, maybe I still shouldn’t build it. But at the age of 10, I would definitely do something bad to myself or my parents’ house, if not both.
Then it gets worse
Another project that I just couldn’t stop reading about was the “homemade atom smasher” developed by [F. B. Lee]. I don’t know about “atom smasher”, but they were linear particle accelerators, so I think that’s an accurate description.
I doubt I have the skills to pull it off today, much less back then. Old refrigerator compressors were run backwards to pull a rough vacuum. A homemade mercury diffusion pump will get you there. Later in life I would work with some of these things using scanning electron microscopes and such, but I was buying them, not cobbling them together from light bulbs, fridges and homemade blown glass!
You also needed a good way to measure low pressure, so you needed to build a mercury-filled McLeod gauge. The accelerator itself is a three-foot-long tube of two-inch diameter borosilicate glass. At the top is a metal ball with a peephole that allows you to see the neon bulb to judge the current in the electron beam. There is a thread at the bottom.
The globe above corresponds to one on top of a Van de Graf generator, which produces about 500,000 volts at a relatively low current. The particle accelerator is definitely linear, but of course all the cool particle accelerators today are looped.
[Andres Seltzman] built something similar, though not exactly the same, a few years ago and you can see how it works in the video below:
What could go wrong? High vacuum, mercury, high voltage, an electron beam and lots of unwanted X-rays. [Lee] mentions the danger of “water hammer” in mercury tubes. in addition [Stong] apparently he felt nervous enough to get a second opinion [James Bly] who worked for a company called High Voltage Engineering. He said in part:
…we are somewhat concerned about the dangers involved. We wholeheartedly agree with his comments regarding the dangers of breaking glass and the use of mercury. However, we feel strongly that discussing the potential dangers of X-rays and electrons is not enough. Even if the experimenter is limited to low atomic number targets, some generation of high-energy X-rays will inevitably occur when using electrons of 200 to 0.300 kilovolts. If currents as high as 20 microamperes are reached, we are sure that the resulting danger is far from negligible. In addition, there will be a significant number of scattered electrons, some of which will inevitably pass through the peephole.
I survived
Clearly I didn’t build either of those because I’m still here today. I managed to make an arc furnace from a long forgotten book. The curtain rods held the carbon rods from some of the D-cells. The rods were in a pot full of sand. The old power cord hooked into the curtain rods, although one wire went through a jar of salt water and created resistance so you didn’t blow the fuses.
I somehow survived without dying of fumes, going blind, or getting burned, but my parents’ house had a burn mark on the floor for many years after the experience.
If you want to build an arc furnace, we would start with a more modern concept. If you want a safer old book to read, try a book by [Edmund Berkeley]developer of Geniac.