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

1941OctPSMath11941OctPSMath2

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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1941 ARRL Battery-Powered Equipment Test

1941SeptQSTToday marks the 80th anniversary of an ARRL contest that, as far as I can tell, happened only one time, the 1941 ARRL Battery-Powered Equipment Test. The announcement shown here appeared in the September 1941 issue of QST, and the full rules appeared in the October issue.

While June Field Day was, and is, dominated by gasoline powered generators, this event was “aimed at individual-class lighter weight equipment.” To stress this, the official contest exchange included the transmitter weight. Participants could work non-contest stations for one point, with an extra point for sending and getting acknowledgment of the transmitter weight. If the other station was battery powered, there was an additional point for copying their transmitter weight.

WFD1In my opinion, the small advantage gained by an electric generator is more than offset by the convenience of operating with batteries.  For example, as I previously reported, I worked the 2021 Winter Field Day contest with my trusty fish finder battery.  Especially if you’re thinking in terms of emergency preparedness, it’s an easy matter to keep fully charged batteries on hand, whereas a generator usually requires a certain amount of maintenance, as well as keeping fuel on hand.

The maximum power level for the 1941 contest was set at 30 watts, although it would have been a stretch to get more from battery-powered equipment. Operation from the field was encouraged, with a multiplier of of 2 for all contacts. However, stations could also be operated from home, as long as batteries provided all power for transmitter and receiver. The contest rules reminded hams that portable operation required 48 hours advance notice to the FCC.

There were categories for both HF and VHF (called in those days “low frequency” and UHF). Interestingly, HF operation was confined to the daylight hours, but UHF could continue all night. The UHF category allowed 5 meters and up, but all of the entries in that category used exclusively the 2-1/2 meter band.

The results weren’t published until after Pearl Harbor, in the March 1942 issue of QST.  They are shown below, with W8RMH, Edgar Cantelon of Detroit, later W8CV, taking the honors for high score with 82 contacts from a portable location. Among the calls is one familiar one, that of Don Wallace, W6AM, whom we have previously profiled.

In the “UHF” category, W2NPN took top honors, with an impressive 72 contacts from a portable location, all on 112 MHz.

The “transmitter weight” is an interesting piece of data to exchange. Even though this contest is no more, transmitter weight is still a factor in at least one contest. While it’s not sent on the air, transmitter weight is an important factor in scoring for the Adventure Radio Society Spartan Sprint contest.  In the most recent running, K4PQC managed 11 contacts with a station (transmitter, receiver, headphones, and battery) weighing in at 0.1268 pounds (2 ounces). He reported that his station consisted of a 40 meter ATS-3b.  The rig is designed to fit inside an Altoid’s tin, but he ran it without the case to shave a whopping 1.2 ounces off the station weight.

I suspect W8RMH’s rig weighed a bit more in 1941, but he probably used a lot of other gear, both larger and smaller, over the years. According to his 2016 obituary, he had just started working at WJBK radio (now WLQV) shortly after this contest, and he was in the transmitter room when the station reported that Pearl Harbor had been attacked. He then secured a new job in a defense plant, later becoming a radio operator for bomber test flights. He later served in the Merchant Marine as a radio operator, and then the army. He later went back to WJBK and served as an engineer for their TV station.

BatteryPowerContestScores1941



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1941 Homemade Toys

1941OctToy1Chances are, the hot new toy that you planned on buying Junior for Christmas is stranded somewhere in a flotilla of container ships off the coast of Long Beach. Maybe they’ll break the logjam before Christmas, but as our Secretary of Transportation had to admit, we probably shouldn’t count on it.

But despite the official concessions of gloom, there’s no reason why ineptitude needs to spoil Christmas. If you get to work now, you can make toys that are far superior to the unobtainium Chinese imports. And for the younger children on your Christmas list, you can’t go wrong with these colorful animals from the October 1941 issue of Popular Science.

All you need is a band saw or jig saw, and a single piece of 3/4 inch plywood 12 by 24 inches. The plywood might be more expensive than usual this year, but it’s probably sourced in North America, and you shouldn’t have much trouble tracking it down. If you don’t already have the saw, keep in mind that they’re also waiting off the coast of California, so you’ll want to get that right away before everyone else gets the same idea.

1941OctToy3Complete plans are found on page 178 of the magazine, which you can read at this link. Instructions are also given for the bases and storage box, as shown below.  The pattern for cutting the animals is shown at left (click on the small image for the complete full-size version).  You simply trace the design onto a piece of 1/2 inch graph paper and use that to cut.  When you’re done, the animals should be painted in bright colors, and the magazine reminds readers to “be sure to use nonpoisonous, washable, enamel” paint.

When finished, the set will keep youngsters happily occupied for many hours. As the magazine points out, the toy teaches how to discriminate between colors, recognize the various animals, develop creative instinct, and rewards the child with a sense of accomplishment, all factors recognized as essential to proper development. Chances are, the Chinese toy doesn’t have all of these advantages.1941OctToy2

 



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1936 Bond Flashlights

1946OctRadioRetailingEighty-five years ago, the radio detailer looking for an additional profit center couldn’t go wrong by stocking a few of these flashlights from the Bond Electric Company. Two models were available, both all metal construction with full chromium finish. Both used two cells, one a floodlight for 39 cents, and the other, for just a dime more, featured a focusing spotlight.

Of course, customers would eventually be back for more batteries, so it was a winning proposition for the long term.

The ad appeared in the October 1936 issue of Radio Retailing.  According to this inflation calculator, the 39 cents works out to $7.52 in 2021 dollars, and the 49 cent deluxe model would be $9.45. How does that compare to the modern equivalent below, which comes in a four pack?  The modern ones use LED’s, and with longer battery life, there will probably be less repeat business for replacement batteries.

You can see more examples of flashlights from this company at this link.



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1981 Grocery Prices

1981Oct15PghPressFor a snapshot of grocery prices 40 years ago, this ad appeared in the October 15, 1981, issue of the Pittsburgh Press.  According to this inflation calculator, each 1981 dollar is the equivalent of $3.01 in 2021 dollars.  So for a fair comparison, you need to multiply all of these prices by 3.

Eggs were just 69 cents a dozen, but when you do the math, that’s the equivalent of $2.08, which you can compare to the current price shown below:

A pound of margarine was 99 cents, which would be about $2.98 in 2021 dollars. Today’s actual price is shown below:

Coffee was expensive, with a 3 pound can of Maxwell House selling for $6.99, or $21.04 in today’s dollars. It’s about half as much today, because the link below shows the price for two 3 pound cans, now in plastic:



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RCA Victrola V-225 Radio-Phono, 1941

1941OctNatlRadioNewsAs we’ve noted before, people used to dress up to listen to the radio or play records, as shown by this photograph on the cover of the October 1941 issue of National Radio News.

The woman operating this phonograph had a good reason to get dressed up, because the radio-phono was the RCA Victrola model V-225. The radio pulled in standard broadcast and two shortwave bands, and it had an automatic record changer.

But calling it an “automatic record changer” is a serious understatement. It was actually a miracle of engineering. Not only would it play the records automatically, but it would play both sides of each record, thanks to a dual tone arm with a needle on both the top and bottom. To play the “B” side, the motor would stop and then change direction. The system is explained in detail in the magazine:

The “Magic Brain,” RCA Victor’s new automatic record playing mechanism illustrated on the front cover of this issue, is magical in its uncanny, almost human operation. The mechanism, by use of a radical new Tandem Tone Arm, plays both sides of records without turning them over.

The turntable automatically moves aside to discard a record which has been played on both sides, and returns to position and finds the center hole of the next record to be played. This feature is unique in automatic record changing devices and is made possible by the use of two motors. one to drive the turntable and the other to operate the automatic mechanism. This also makes it possible to increase the capacity of the mechanism to fifteen 10-inch records or twelve 12-inch records.

As soon as the Tandem Tone Arm bas played both sides of a record, it swings free to permit the turntable assembly to tip over to the left, gently carrying the record into the padded pocket below the mechanism. While the turntable is in this position, the next record in the stack drops silently to the heavily felted motor board. The turntable then returns to its original position, raising the record from the motorboard enroute. While the record is held in position by the record support posts, the turntable spindle seeks out the center hole of the record to be played and finds it, positioning the record for playing. The turntable is no larger than the size of the record label, in order to permit the lower section of the Tandem Tone Arm to play the under side.

The Tandem Tone Arm is actually two complete Magic Tone Cell pick-ups set, one above the other. into a tune arm shaped somewhat like at tuning fork. Its action is completely automatic from the time it leaves the rest position at the touch of the starting button, until it returns to rest after the last record has been played. Since the vibrating parts of the unit weigh less than a postage stamp, no undesirable mechanical noise or needle chatter is created.

Among the many other features which are attracting much interest as the ‘Magic Brain” is demonstrated are the Magic Tone Cell (or pickup cartridge), the Flexible Toue Bridge and the Jewel-Lite Scanner. The Tone Bridge connects the sapphire Jewel-Lite Scanner (replacing the standard needle) to the Magic Tone Cell.

The new “Magic Brain” with its Tandem Tone Arm is incorporated in the 1942 RCA Victrola model V-225 combination three -baud receiver and automatic phonograph, which is the receiver pictured on the front cover.

You can see this remarkable changer in action at the following video:



1941 Electro-Mechanical Oscillator

GeneralRadioExperimenterThis site often features science fair projects, and we often specialize in impressive projects that can be whipped together in one evening. This project doesn’t come in that category, but the advanced student who is willing to do some tinkering can replicate this tuning fork oscillator from the October 1941 issue of General Radio Experimenter.

Shown above is a tuning-fork oscillator utilizing a vacuum tube and a tuning fork. It is used to produce a very precise audio tone using an electro-mechanical process. The vacuum tube serves as the oscillator (and a modern recreation could just as easily use a transistor), and a mechanical tuning fork serves to determine the frequency. A simplified schematic diagram is shown below. The tuning fork needs to be ferrous in order for it to work.

WWV 1927 frequency standard. Wikipedia image.

WWV 1927 frequency standard. Wikipedia image.

A similar circuit was used for the frequency standard for WWV in 1927, as shown at the left.  Advanced students wishing to duplicate this project will find some guidance at this site and this site.  Students looking for the more familiar last-minute but impressive projects can browse our science fair category for ideas.

GeneralRadioExperimenter2



1946 Compass/Match Case/Fire Starter

1946OctBLSeventy-five years ago this month, the well equipped Scout might have in his pack this combination compass, match safe, and fire starter. A compass was at the top, with a window to view the direction. To avoid confusion, the window was labeled “YOU ARE LOOKING” to make clear that if you saw an N, then you were looking north, rather than having the N printed on the north side of the dial.

Matches were stored in a watertight container, but just in case you ran out, the side had a “flint of pyrophoric metal” that could be struck by a knife. The ad declared that it was the only compass “that can build a fire in a split second,” and I’m guessing that would be done with one of the matches inside. With practice, the flint would probably work, but it would take some practice, and probably wouldn’t happen in a split second.

The product was manufactured by the DuPage Plastics Company, 10 South LaSalle Street, Chicago. It was officially approved by the BSA, and is advertised here in the October 1946 issue of Boys’ Life.


While this particular model is no longer available, there is a modern replacement, shown at left. I have one of these, and while I’m not sure it’s from the same manufacturer, it looks identical. There’s a compartment for storing matches, and as far as I can tell, it is waterproof. Strike anywhere matches are still available, but they’re often hard to find. I simply use regular strike on box matches and include one of the strikers from the box inside with the matches. If all else fails, it does include on the side what is now called a ferro rod.

The modern version also includes a whistle, which is quite loud, as well as a tiny mirror inside the cap, which presumably could be used for signaling.

I’m guessing that the compass on the 75 year old version was better than the modern one, but the modern one does, indeed, work. You have to be careful, however, because if you don’t hold it perfectly level, it will bind up and not move. The best way to use it is to check it once, and then check a second time to make sure that north hasn’t moved.

Especially if you buy the three pack, the modern version is very inexpensive.  Like this Scout 75 years ago, it’s not a bad idea to have one of this in your pack.



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