Category: Office Tech

It will be recalled (blog article) that I had recently started getting familiar with an inexpensive inverter welder.  What became pretty clear early on is that the number in the display does not match the number of amperes of welding current delivered to the welding rod. Alert reader Dave posted a comment:

Can you accurately anticipate what amperage to expect given the readout on the machines as a ratio to the readings you have gotten on the ammeter? Perhaps this is an opportunity to do some more experimentation…

Prompted by alert reader Dave, I did some more measurements.  Here are the results.

Continue reading “Welding current redux”

(followup:  I have now measured more welding currents — blog article)

It will be recalled (blog article) that I recently took a stick-welding course.  I also recently purchased an inexpensive inverter-type welding machine (shown at right), and a neighbor of mine also purchased an inexpensive inverter-type welding machine.

Each welding machine has a rotary knob for picking the welding current.  And each welding machine has a three-digit numerical display.  The question that arose for my neighbor and me was, can we safely assume that the number in the display will be the number of amperes of actual welding current?  The answer turned out to be “no”.  Continue reading “Measuring welding currents”

Readers of this blog are already aware that I enjoyed the movie Glass Onion (blog article), from writer/director Rian Johnson.   At about the time that Glass Onion became available for streaming, it came out that Johnson had just gotten done creating, writing, and directing a ten-episode television series Poker Face (Wikipedia article).  I have greatly enjoyed all five episodes of Poker Face that have aired thus far.

Which brings us to episode four of Poker Face, entitled Rest in Metal.  This episode has a plot element called a “Death Capacitor”.  Which is what I will now discuss. Continue reading “Death capacitors”

The executive summary for this blog article is that ethernet is faster than 5-gigahertz wifi, and 5-gigahertz wifi is faster than 2.4-gigahertz wifi. (I imagine that most readers of this blog already expected this to be the case.) Continue reading “Choosing a LAN type”

It turns out that anybody who wants to, can publish things on SSRN (Wikipedia article).  SSRN, it will be recalled, is an initialism for Social Science Research Network (web site).  To test this out, I created an account at SSRN and uploaded The Fool’s Errand that is DOCX.  You can see it here:  https://ssrn.com/abstract=4346907.  This blog article describes the process and the results.  Continue reading “Publishing things on SSRN!”

Folks, the subject line says it all.  When I am assembling a plastic model kit, should I glue the parts together, and then paint the parts?  Or (as the instructions seem to suggest) should I paint the parts first, and then glue them together?  Continue reading “Paint first or glue first?”

I imagine many readers of this blog have some idea how a clamp-on AC ammeter works.  You have some wire with AC current in it, and you open the jaws of a clamp-on meter and you close them around the wire.  The alternating current makes a constantly changing magnetic field around the wire.  It is a fairly realistic goal for the jaws to capture basically all of the lines of (constantly changing) magnetic flux surrounding the wire.  If you have the luxury of being able to assume that the frequency is known (and depending on the continent where you are located, this may well be a safe assumption), you can proceed in a very straightforward way to design a simple and inexpensive and quite accurate AC ammeter. I have had this Micronta (Radio Shack) meter (seen at right) in my tool kit for some fifty years now, and it has served me very well.

But nowadays there are clamp-on DC ammeters. A wire carrying a DC current does not (by definition it does not!) generate any changing magnetic field!  A traditional meter like the one described above has nothing to measure if it is clamped onto a wire containing a DC current.   How can a clamp-on DC ammeter possibly measure a (perhaps constant) DC current? Continue reading “How clamp-on DC ammeters work”

One of my pastimes is trying to guess which sound bites, if uttered at a cocktail party, might lead to the turning of heads and might lead to other party guests clustering around with great interest.  (See past blog articles.)  Here is another:  diatomic carbon.  Continue reading “Diatomic carbon”

The religious scholar Maimonides from 900 years ago (Wikipedia article) wrote about lots of things including the best kinds of charity.  He fingered a telltale:  what if the donor gives anonymously?   The anonymous gift of charity is the highest kind of charity, said this religious scholar.

Which brings me to the strong emotions that I felt as I read a flurry of recent news stories about a fellow in a rural part of Alabama who did not have very much money, but who (after his recent death, it comes out for the first time) had been dropping by a local pharmacy for some ten years and had been handing the pharmacist a $100 bill each month with instructions that the money should be applied toward prescriptions for people who could not afford their drug prescriptions.

One of his very strict instructions to the pharmacy was that nobody was to be told where the money came from. Continue reading “The best kind of charity”

Each time I install another internet-of-things (“IOT”) device in my home, it is always the same:  the device requires that I tell it the wifi password for the Internet connection in my home.  The app that needs to be installed on my smart phone to get the IOT device working also asks lots of intrusive things, and demands to be given access to my “location”.  This leads to a situation where the IOT device could be a security risk for trusted devices on my local area network.  What can be done to reduce or eliminate the security risks presented by the dozens of IOT devices in my home?  Part of the answer is to set up a VLAN (virtual local area network).  Then the IOT devices are denied any opportunity to have any access to my trusted devices.  I will describe how this is done.

Continue reading “Setting up a VLAN for your IOT devices”