Monthly Archives: October 2021

1991 Halloween Blizzard

Today marks the 30th anniversary of the Great Halloween Blizzard of 1991.  In Minneapolis-St. Paul, snow started falling in the late afternoon. By midnight, 8.2 inches had fallen, a record for that date, and also for the entire month of October. Before the snow stopped falling three days later, Minneapolis-St. Paul had received 28.4 inches, and Duluth 36.9 inches.

Twenty-two persons died in the storm, which was followed by record cold temperatures that hindered snow removal. Schools were closed the following day, a Friday, with some remaining closed the following Monday.

Trick or treating was largely a victim of the storm. At the time, I lived in an apartment building, so had a handful of kids from the building trick or treating.  But for most, the traditional activity was impossible.

You can view WCCO-TV coverage of the storm at this video, posted courtesy of TC Media Now:



Science Fair Project: Homemade Battery

1961OctPE1If Junior is looking for a project for the science fair, a good standby is always making a battery out of materials found around the house. We’ve previously covered the idea in more detail, but the October 1961 issue of Popular Electronics shows a slight variation. All of these are a variation of Allesandro Volta‘s Voltaic pile from 1799, and are easy to recreate.

This one uses strips of copper and aluminum. The mechanical details are unimportant, so you don’t have to worry about the exact shape. The aluminum can be cut from a soda can, although these have a plastic lining on one side and paint on the other, so the aluminum will need to be sanded. If you don’t have a strip of copper available, a piece of copper wire, or any kind of copper hardware found at your local hardware store will work fine.

The 1961 article uses the battery to power a one-transistor radio. As you can see below, it consists of a crystal set with one germanium transistor amplifying the audio. But to show that the battery is working, a light emitting diode would work just fine. Polarity is important, so if it doesn’t light at first, simply reverse it in the circuit. In this battery, the copper is positive, and the aluminum is negative. It will come to life when the two electrodes are placed in salt water. As shown in this picture, you can carefully put one drop between the electrodes, or simply place it upside down in a glass of salt water.

Junior’s experiment for the science fair can be to see how much salt in the water results in the brightest glow. Or he or she can try different electrolytes, such as bleach or lemon juice. Very little can go wrong, and as long as some liquid is between the two strips, the LED is almost certain to give off a little light.

As we noted previously, the project is very easy with materials found around the house.  But for students who want to bypass the procurement process, you can simply go out and buy one of the potato clocks shown at left.

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1921 Homemade Phonograph

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A hundred years ago, the cost of a phonograph was becoming reasonable so that most Americans could afford one. But for the frugal handyman, there was another option, as shown here in the October 1921 issue of Popular Science.

Not only could the home craftsman make his own phonograph and save some money, but the homemade version would be superior to most commercial phonographs. The majority of the machines were hand-crank phonographs, but this one was electric, relying on a motor powered either by batteries or household current.

TypewriterEraserThe platter was made of a piece of brass, with another strip of brass soldered to the edge. This was driven by the motor using a friction drive made of a typewriter eraser
like the one shown here. Surprisingly, you can still buy a manual typewriter, but this style of typewriter eraser is no longer made. Like everything, however, you can find them on eBay.

The magazine explains how to construct the pickup and tone arm, which consists of a brass tube and the lid from a jelly jar. The board at the rear not only supports the tone arm, but serves as a sounding board, presumably providing room-filling audio.

One issue that is not addressed by the article is how to regulate the speed, since the motor will need to be spinning at about the right number of revolutions per minute. The relative size of the eraser and platter will, of course, provide some gearing, and there would be some room for experimentation. And with a DC motor, the voltage could be used to get the speed right. But the motor is going to have to start out at approximately the right speed, so some experimentation would be necessary for which motor to use.

As long as the craftsman got the bugs worked out, the result would be a quality phonograph, albeit not as aesthetically pleasing as the one normally found in the parlor. Students looking for an interesting science fair project can follow the instructions provided by Mr. Wizard in the video below.  All you need is a pencil, a pin, a piece of construction paper, some tape, and, of course, a record that you don’t mind suffering possible damage.



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Young Soviet Nuclear Scientist, 1961

1961OctYTI’m not sure exactly what’s going on in this illustration, but the young comrade seems to be having a good time, even though both the tree and the bird are rather distressed.

At the top, it seems to read that the diode tube, plus “plasma”, plus “reactor” equals whatever is in the bucket that is powering the tool. So very possibly, this young man went on to a career in science, such as designing the Chernobyl nuclear plant.

Whatever it is, it appeared in the October 1961 issue of Юный техник (Young Technician).



1941 Baseball Radio

1941OctPMbaseballIn 1941, for the sports fan who wanted to listen to the baseball game on a baseball, this All American Five was available. The ball was about nine inches in diameter, and had tuning knob on one side and volume on the other.

The radio bore the “Trophy” name, and as you can see from the handwritten notation, it came from the D.A. Pachter Company, Space 1142, Merchandise Mart, Chicago. The company had a wide selection of novelty items, some of which you can see in this 1950 catalog.

They included a matching bowling ball radio, which you can see here.  A nicely preserved example of the baseball radio can be seen at this link.  The photo above appeared in the October 1941 issue of Popular Mechanics.



1951 Three Tube British Receiver

1951OctRadioConstrThe plans for this handsome three-tube set are shown in the October 1951 issue of the British Radio Constructor magazine. The set uses three 6AG5 tubes, which were said to be readily available at Government Surplus Stores. One disadvantage of the tubes was the non-variable Mu characteristics, which meant that a conventional volume control was not possible. Undaunted, the volume control is placed in line with the antenna, which could be as short as a few feet. The volume control would be rendered inoperative if the antenna coil picked up signals, so the article explained how to shield that coil.

In the circuit below, the set is for the medium wave band only. If long waves were desired, a second set of coils were used, and switched into the circuit. The band switch also had a third position to power off the set.

The circuit was designed by Peter T. Pitts, G3GYE, who died in 2020 at the age of 92.

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1961 Paper Clip Radio

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Sixty years ago, this gentleman was undoubtedly one of the first on his block to own a transistor radio, thanks to the circuit described in the October 1961 issue of Popular Mechanics.

As shown below, the set was an unassuming two-transistor circuit, with a 2N170 serving as detector and 2N107 as audio amplifier. You had to decide which half of the broadcast band you wanted to tune, as the loopstick couldn’t quite tune the whole band, and the value of the capacitor depended on whether you wanted the lower half or upper half.

The set had two alligator clips, one of which served as the on-off switch. The other one was used to hook to a convenient antenna. The set was constructed on a PC board, and the parts list called for the board, the marker, and the etchant solution. The set’s gimmick was the X-shaped paper clip, which could be used to clip the set to your pocket as shown, or to serve as a bookmark while reading.

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1941 Radio-Phonograph Table

1941OctPsPhonoStandThe October 1941 issue of Popular Science showed how to put together this radio-phonograph stand. The phonograph was placed in a drawer, not just for aesthetics, but to improve its performance by muffling the needle scratch and motor noise.

The record player typically plugged in to the phono jack on the back of a radio, which was placed on top of the table. The bottom shelf could be used for record storage. The magazine noted that the the table could be built with a dollar’s worth of lumber, a sheet of plywood for the table top and drawer base, and white pine for the rest of the design.



1921 Signaling Device

1921OctPSA hundred years ago this month, the October 1921 issue of Popular Science showed this signaling device for use by the military. It provided a level of security, because its light beam was visible only over a small area. It’s a very simple idea–it consists of a telescope with a flashlight bulb mounted inside at the focal point. It was easily aimed by looking through the telescope. The bulb’s filament was visible, and it was simply a matter of lining it up so that was visible over the spot where you wanted your signal seen.

Students looking for a science fair project could easily recreate this.  All that’s needed is a toy telescope like the one shown here.  It can be carefully disassembled and the bulb place inside.  You can use the bulb from an old flashlight, or buy the bulb separately.  For this project an old-fashioned incandescent bulb will work better than an LED.

You’ll also need some hookup wire and batteries.  While not absolutely necessary, a battery holder will make the job a lot easier.  Normally, for a science project involving light bulbs, it’s most convenient to get a socket for the bulb.  However, in this case, the socket might not fit.  Therefore, the best option would be to solder the wires directly to the bulb.  A soldering iron, complete with solder and everything else you need, is surprisingly inexpensive.

To send Morse code, you’ll also need a small pushbutton switch.



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Mathematics for Self Study/For the Practical Man: 1941

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I find this ad intriguing on a number of levels. This particular instance is from 80 years ago this month, from the October 1941 issue of Popular Science.  (You can click on either image to see a full size view of that page.)

Presumably, the publisher was able to make enough money to pay for two full pages in a national magazine by selling a five-volume set on mathematics for $8.95 over three months ($166.56 in 2021 dollars, according to this inflation calculator).  Somehow, I doubt if they would have enough takers today.

The title of the series is “Mathematics for Self Study,” and it gets more curious when you consider the five individual volumes. They cover arithmetic, algebra, geometry, trigonometry, and calculus. One would think that the prospective customers for the arithmetic volume would have little overlap with the ones buying the calculus book, but here they are, offered as a package deal.

The author is James Edgar Thompson, of the Department of Mathematics of Pratt Institute in Brooklyn.

Even though it seems odd at first, there does appear to be a continuity between the books. The first volume, for example, appears to be much more than a primer on the subjects that were covered in elementary school. According to the ad, the arithmetic text starts with a quick review of principles, but then “presents all the special calculation methods used in business and industry which every practical man should know.”

The practical value of the set is stressed throughout the ad. The algebra book shows how to solve problems which are “involved in all military and industrial work.” Geometry covers all of the topics essential in drafting and engineering. Trigonometry covers the essentials for machine work, land surveying, mechanics, astronomy, and navigation. And the calculus book, “the branch of mathematics that deals with rate problems” allowed the solution of problems regarding areas such as efficiency and velocity. It noted that calculus was applied directly in the design of rifles and cannon.

The preface of the calculus volume explains the inherent continuity of the books:

In arithmetic we study numbers which retain always a fixed value (constants). The numbers studied in algebra may be constants or they may vary (variables), but in any particular problem the numbers remain constant while a calculation is being made, that is, throughout the consideration of that one problem.

There are, however, certain kinds of problems, not considered in algebra or arithmetic, in which the quantities involved, or the numbers expressing these quantities are continually changing. Many such examples could be cited; in fact, such problems form the greater part of those arising in natural phenomena and in engineering. The branch of mathematics which treats these methods is called the calculus.

I found a few modern reviews of these books, and almost without exception, the reviews are overwhelmingly positive. I’ve seen a few complete sets of the books for sale, for hundreds of dollars. However, for those wishing to acquire a set, it can be done economically. The same set of books was published over many years, and there are slight variations of the titles. The set sold in 1941 was entitled “for self study,” but later editions seem to have adopted “for the practical man” as the title. As far as I can tell, there were few changes, so Arithmetic for Self Study is probably essentially identical to “Arithmetic for the Practical Man.”

If you don’t mind a bit of variation, you should be able to find all five volumes at a reasonable price. The links below should help you find them.  In many cases, the prices of different editions can vary considerably, so you’ll want to check all of the links below before placing an order.

    • Arithmetic

    • Algebra

    • Geometry

    • Trigonometry

  • Calculus

The set was published by the D. Van Nostrand Company, which I believe is most famous for its behemoth Van Nostrand’s Scientific Encyclopedia. Of course, if you want to read all of the books at no cost, they are available in many public libraries. You can find them at Worldcat, and your local library should be able to get them with interlibrary loan.



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