Vacuum Systems-  The Wrong Stuff

Posted on by
The cost of the learning curve.: hoses and fittings that ended up NOT being helpful in reaching my target vacuum.

My idea of creating a vacuum was terribly simplistic.  Just run a pump until you reach your desired vacuum, right?.  Well… I learned that there is much more to it. 

First, there are different degrees of vacuum, categorized by how difficult it is to attain them.  The easiest can be obtained by a mechanical pump, a piston, or equivalent, pushing air molecules from the chamber to the outside, essentially a reverse bicycle pump.  It is possible to remove 99.9% of the air molecules and a few more, but that still leaves too many for the cool vacuum electron effects like neon signs, nixie tubes, and for audiophiles, amplifier tubes.

The mechanical vacuum pumps can’t reach those levels; more exotic pumps are needed, but they can get close to where radiometers operate, which is my interest.  So following the advice of expert friends, I acquired a pump that, in principle, could reach the level of vacuum I needed:  50 microns (a micron of mercury air pressure is 1/760 thousandth, call it a millionth, of standard atmosphere).  The pump model I bought is commonly used by the HVAC industry, where air conditioning units need to be evacuated before charging them with refrigeration working fluids (Freon, etc.).  They can reach the 50 micron vacuum level internally, but if you connect it to a real world vacuum chamber, there is a myriad of “leaks” that will prevent getting there.

I found this out by trial and error.  I found that the hoses, fittings, and gauges from the HVAC world were not cheap, but there is a market to keep them reasonably affordable to the industry’s practitioners.  Vacuum-rated hoses, gauges, valves, and fittings (the connectors between vacuum elements that minimize leaks), are hard to make.  And they all seem to have their own connection systems.  I learned about “flare” fittings, “nominal pipe thread” and tapered thread, acme threads, o-rings, and a bunch of other methods for connecting things and trying not to leak air molecules.

Continue reading →

Glass Blowing- Getting the Right Stuff

Posted on by
The “candles” in a neutral flame from my torch.

I decided that to become more skilled, I would need my own torch and materials so I could practice and make as many mistakes as needed to acquire a specific glass-blowing skill.  I found a torch on eBay, some hoses and fittings on Amazon, a tank of propane from my barbeque grill, but then had to figure out an oxygen source.  I also needed an exhaust system so I wouldn’t asphyxiate while heating glass from my propane-burning torch.

The exhaust system was simple in principle, but of course, the actual implementation was not.  I wanted to create a “glass working station” in a corner of my garage/workshop—a recently built structure with a 10-foot high ceiling with no explicit ventilation.  This has already been a limitation when I wanted to work with paints, adhesives, or solvents that required a ventilated area, so I welcomed the excuse to create a ventilation zone for my shop.

Professional paint and chemistry booths are expensive, so I looked for kitchen exhaust hoods.  I discovered that they have an enormous price range which depends almost entirely on the current popular style and appearance of the sheet metal hood, and almost nothing on the exhaust rate of the fan.  The typical kitchen exhaust rate was less than I wanted anyway, so the fan didn’t matter—I would be replacing it.  I really wished I could buy the exhaust hood sans fan motor, but they are rare.  And when you find them, they cost the same or more.  It’s the external visual style you are paying for. 

I found a low-cost, unattractive but functional, kitchen exhaust hood with a low-power motor that I could replace with one that was more capable.  It seems a huge waste, but these are the tradeoffs in the DIY world.

Continue reading →

Toward a Personal Radiometer

Posted on by

I was recently struck by an unexplained desire to craft a classic scientific object, a “radiometer”.  It was first created and demonstrated in the 1800s as scientists explored the fundamental elements of nature, especially the behaviors of atoms and molecules.  The periodic table and the ideal gas law that we learned in school were figured out during this time through many careful experiments.

Among the experiments was one performed by William Crookes while trying to isolate and identify his newly discovered element Thallium.  To make high-precision measurements of mass, he avoided the disturbances of air currents on his balance by putting it in a vacuum.  But he found that the readings were still varying, depending on whether the balance was in sunlight or not.  With his laboratory skills, he crafted a device to demonstrate the effect, a device that today is known as a “Crookes radiometer”, or “light mill”.  It is a delicately balanced arrangement of vanes, black on one side, white or silver on the other side, suspended in a glass vacuum tube.  Crookes discovered that when the vanes were illuminated by sunlight, they moved, rotating around the balance point, demonstrating that light induced some force to cause the rotation, and that force was also responsible for the variations in his mass measurements.  See this account for a wonderful history of the radiometer.  There is still some scientific uncertainty about how exactly it works!

My fascination with the Crookes radiometer began as a child when I first saw one spinning in a store window.  My dad was with me and was able to explain it to the satisfaction of his 8-year-old son:  “The light hits the white side and bounces off, but it gets absorbed by the black side and the difference of force makes it move”. 

I immediately set out to make one for myself.  With black and white construction paper I made some vanes and taped them to a pencil.  I found a sunny spot in our backyard and planted the sharp end of the pencil into the ground.  Nothing.  No motion.  It was quite a disappointment. 

When I later explained to Dad that my radiometer didn’t work, he told me that the force of light is very small, and for it to spin required a very delicate balance and removing the air from around the vanes, which was why the radiometer at the store was inside a glass bulb.  It explained why my backyard radiometer had failed, but it didn’t quench my curiosity. 

Continue reading →

Know-How for Whom?

Posted on by
The QSL postcard sent through the postal service is the mechanism used by ham radio operators to confirm their over-the-air radio contacts. This is my dad’s QSL card for his Idaho station.

As an electrical engineer I learned that “all digital devices comprise analog components”.  This has remained true even as quantum effects are now being utilized in computational logic gates (they are defined by analog wave functions).

Radio waves, especially those used by amateur radio operators, are analog signals transmitted and received by oddly shaped and configured pieces of conducting metal parts known as “antennas”.  And the techniques to couple a useful signal to them are part of the arcane art and science of amateur radio.  The sharing of this knowledge is a big part of the ham radio community ethos. 

So I should not have been surprised to receive an email asking for help with “s-meter calibration” of an antenna.  It was addressed to my dad, who died in 2016, but whose email address has been set to forward everything to me.  I get occasional messages from this account, but with diminishing frequency, and usually from some company or service he had subscribed to, but for which there was no “unsubscribe”.  In this case however, it was from one of his fellow ham radio acquaintances looking for advice.

Continue reading →

Thor and Poldi’s Eclipse Reprise- the invitation

Posted on by
Approaching totality at the Snake River

In 2017 we hosted a gathering of friends at a campground in Idaho to observe a spectacular total solar eclipse.  Seven years later, the sun and moon will once again align over the US, and we have reserved a small section of Texas, 500 meters from the eclipse centerline, to observe it, hoping to repeat that earlier wonderful experience.  

Many of the original eclipse revelers are planning to join us again, but there are some remaining campground openings.  If you are intrigued by the possibility of witnessing a total solar eclipse, please review my original invitation, descriptions, and links below, especially the update that includes the costs of the accommodations.  If you think you’d like to join our eclectic group of eclipse chasers, let me know.  Otherwise, you may want to plan for the next total eclipse in the US… in 2044.

Continue reading →

Field Trip: Harvard Biology Labs

Posted on by
A panorama of Harvard’s Biology Laboratories building, distorted by the wide angle view (click to enlarge, then click again to see animal frieze details).

I wrote earlier about the unique entrance to Harvard’s Biological Laboratories building, which today is home to the Department of Molecular and Cellular Biology.  My grandfather, who studied in the then state-of-the-art laboratories shortly after being built in 1931, had taken a photograph in the entry of the building.  I found it to be a beautiful image that captured the novel decorations on the doors and their shadows cast onto the marble floor.  I wanted to see and experience this space.

The opportunity presented itself when Poldi’s “Italian sister” Rossella decided to visit while Poldi was in New York– she also expressed interest in seeing Boston, a few hours away.  I invited myself to join their mini-fall tour of New England and they humored me by helping locate the Biology Labs building on the Harvard campus.  It was as distinctive as I had imagined.

The exterior of the building is adorned with animal friezes designed by Katherine Lane Weems, pneumatically carved into the crest of the brick façade.  It is a large building and the animals overhead command your attention until you notice the life-sized rhinoceroses at ground level, also created by the young artist, and which have become mascots (“Victoria” and “Bessie”) for the Harvard biology community. 

Continue reading →

One Cup of Coffee

Posted on by

I recall visiting my grandmother and noticing a large coffee cup that stood apart from the rest. I learned that this was a cup that was reserved for use by her father (my great-grandfather) when he came by to visit each week. She would make coffee and they would update each other on family news.

My great-grandfather was an immigrant from Sweden with a strong work ethic and a clear set of moral principles. Among them was that one shouldn’t live to excess, so he allowed himself only a single cup of coffee. With this restriction, a normal cup of coffee wouldn’t last long enough to be done visiting his daughter. She solved this by obtaining a very large cup for him to use whenever he stopped by.

Evidently, this story was so good that Poldi remembered me telling it to her years ago when I inherited that heirloom. When she encountered a similarly sized cup with my sunflower “totem”, she acquired it and presented it to me as a birthday gift. Well, I don’t have the same restriction for coffee consumption, but I will now be able to say that I had only one cup of coffee in the morning.

Late Life Love– continued

Posted on by
Inside the Wirth Picnic Pavilion with friends and family

Six months ago I posted an item that described my transformation from being a marriage skeptic to being a proponent, while my partner had experienced the reverse conversion.

Regardless of any marriage decision, we made plans to host an anniversary party. Ten years had passed since our “(happily ever) After Party” and our commitment ceremony, and we thought it would be fun to have everyone back to celebrate life, love, and a decade of wonderful experiences, with our family and friends.

Continue reading →

Zoom me up, Scotty

Posted on by
Who are these people, and why are they jumping out of hyperspace?

This is a computed image. It started as a snapshot of a group at a lunchroom table. There was nothing particularly significant about it except as a record of a pleasant reunion of this group of old friends. And like many such shots of a group at a long table, it is hard to get them all in the frame and to represent each member in a photogenic pose. In particular, the persons at the far end of the table are lost in the distance. It is particularly noticeable with wide-angle lenses, the default for phone cameras.

My test image, a scene shot using a wide angle lens of a group at a table.  Photo courtesy Fred Nourbakhsh.

I wondered if I could re-image this scene so that the people are more equally sized, the furthest members are not so small, and the closest not so big.  This is what would naturally occur if the photographer used a longer focal length lens and stood further back. This is an account of what I learned.

Continue reading →