Ninety years ago, it was clear that television was going to be the next big thing, and the November 1928 issue of Radio News contained all of the information needed to get started.
In addition to showing the plans for the mechanical set shown here, the magazine carried the television schedule of the magazine’s flagship station, WRNY.
Ninety years ago this month, the November 1928 issue of Popular Mechanics showed how to put together this trickle charger for your set’s “A” battery (the one supplying filament voltage, which appears to be 6 volts in this case).
The voltage was dropped over two lamps in parallel, and the current was rectified by a homemade rectifier consisting of a strip of aluminum (as pure as possible) and strip of lead, in a solution of borax. The article noted that the charger wouldn’t do much good for a completely dead battery, but by hooking up the trickle charger when the set was not in use, it would keep it topped off.
This tutorial on soldering appeared 70 years ago this month in the November 1948 issue of Popular Mechanics.
It reminds you to keep your trusty Eveready flashlight handy when soldering. First, you can use it to locate the broken wire. Then, you can prop it up to brightly illuminate the work area.
This ad for the American Basic Scientific Club appeared inside the back cover of Boys’ Life 60 years ago this month, November 1958. For only $3.45 each, the club would send one scientific kit per month for eight months, each containing an interesting project on subject such as radio, meteorology, atomic energy, and photography. At the end of eight months, the student would have a working regenerative receiver, signal tracer, code practice oscillator, darkroom (including enlarger), and many other scientific instruments.
I don’t recall hearing about this club, which was apparently in decline by the 1970s when I would have been interested. There’s an interesting history of the club at this website, written by the son of the founder. And a picture of the three-tube regenerative receiver, along with a partial schematic, can be found at this link. The set appears to be mounted on a chassis made of a single piece of metal, mounted on the cardboard box in which the kit arrived. It does have a power transformer, making it relatively safe for the young experimenter.
One of the books included with the kits was a guide to obtaining a ham radio license. It appears that the receiver could be built for either the AM broadcast band or 80 meters, meaning that it probably made a workable receiver for a new novice.
Eighty years ago this month, the November 1938 issue of Radio Craft carried the plans for this handsome one-tube regenerative set built around a type 1231 pentode tube. The tube appears to be unobtainium today, and was an amplifier tube used in early television circuits. It appears that a more available 7V7 can be substituted.
The author reported that he was tasked, right before deadline, in whipping up a circuit and construction article for a simple receiver, and designed and built the set in a single evening before sitting down to write the article. With just a short wire dangling out the window of a modern steel building, the author reported that both broadcast and shortwave stations began pouring in.
75 years ago, wartime shortages meant that meters were not readily available. The November 1943 issue of Popular Mechanics offers this tip for checking whether high voltage is present. A small capacitor (.25 to 2 uF, 400 volt) has spaghetti tubing placed over the leads, which are connected where the high voltage is being tested for. The capacitor is then removed and the ends shorted. A spark indicates the presence of high voltage.
From the October 1938 issue of Popular Science, this photo is self-explanatory: For a convenient source of electric power, all you need is a generator on the rear bumper, hooked to the drive wheel with a belt and pulley. It can be used in motion, or when stopped, simply by jacking up the rear wheel.
Shown here is a crude but functional homemade transistor from 1948, from the October 1948 issue of Radio News. While the author had not yet used the fragile device in a working circuit, he did note that he achieved amplification by a factor of up to 50. The transistor was very unstable at that high amplification, but it did work reliably amplifying by a factor of 15.
The transistor was made of a 1N34 germanium diode carefully broken open. One lead was kept intact, and the other two contacts were made by making cat whiskers out of filaments of old tubes.
The article cites some 1920s articles where the authors made “amplifying crystals” by a similar means. By applying the techniques in this article, the advanced student could prepare a science fair project that his or her teacher would probably declare impossible–making a homemade transistor.
If you need some distilled water, it’s usually a pretty easy matter to go to the local supermarket and buy a convenient gallon jug. Or, if you’re willing to pay for the convenience, you can even order it on Amazon.
But it’s also easy to whip up a small batch at home, as shown in this self-explanatory photo from Radio News, October 1928. The hanging container is filled with cold water, preferably ice water. It should be as thin as possible. The spout of the kettle is directed at this container, and the distilled water drips onto a plate below.
The idea was sent in to the magazine by one C.A. Oldroyd.
If the aspiring young scientist needs distilled water for a science fair project, adding this method to the project will almost guarantee the elusive blue ribbon.
This cartoon appeared in Radio News, November 1938. It’s equally appropriate today. For more information, visit myARRLvoice.org.