If you need to liven up Junior’s next party, you can put together this circuit for a fun game of “hunt the bleeper,” as described in the November 1972 issue of Practical Wireless.

The magazine noted that British children love noise, and this is equally true on this side of the Atlantic. The beeper, which draws only 600 microamps, puts out a high pitched tone at a low level. The device was to be hidden, and the children would be split into two teams to find it. There were two strategies available: They could concentrate on finding the device, or they could make so much noise to keep the other side from hearing it.

The cost was said to be 50 pence, which didn’t include the case, which was one of the then-ubiquitous 35mm film can, which was deemed to be free. Even though they’re no longer free, like everything else, you can find them on Amazon.

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Seventy-five years ago, this microwave relay station was under construction atop Jackie Jones Mountain near Haverstraw, NY. It was one of seven microwave relay stations linking Boston and New York, delivering television programs with a 1 watt signal on 4000 MHz.

It is pictured here on the cover of the November 1947 issue or Radio News.

Sixty years ago, the May 1962 issue of Electronics Illustrated featured these two projects to build unlicensed devices for use on 11 meters. The first is the walkie-talkie shown at the top. The three-transistor transceiver was powered by two mercury batteries. It’s 100 milliwatts were said to have a range of about 1000 feet.

The other project is a transmitter to be installed in a model rocket, weighing in at only 1-1/8 ounces, including battery. It had a range of about 1500 feet. The circuit was shown for 11 meters, where it could operate license fee, but the magazine also pointed out that good results were had on 10 or 40 meters for licensed hams.

Various types of telemetry could be used, but to start, the magazine recommended a photocell, mounted near a small hole in the side of the rocket. This would allow a measurement of the rocket’s spin, since it would oscillate in time with the photocell pointing at the sun.

If you were wondering what the most wished-for radio of 1947 was, this was it, at least according to the manufacturer, the Automatic Radio Manufacturing Co., 122 Brookline Avenue, Boston.

The radio in question was the Tom Thumb portable, a four-tube (plus selenium rectifier) portable that came with its own rechargeable battery, undoubtedly a two-volt lead-acid cell. It could operate off battery, AC, or DC, and the battery could be charged internally (but now with the radio playing).

It was rather pricey, at $47, the equivalent of over $600 in 2022 dollars.

The ad appeared in the May 1947 issue of Radio Retailing.

Eighty five years ago, this couple are enjoying the luxury of a built-in radio, thanks to a little ingenuity by a reader of Popular Mechanics, who sent in this idea for the April 1937 issue.  A reader took one of the magazine’s designs for an AC-DC midget receiver, modified the panel dimensions slightly, and built it into a modernistic bookcase.

Here’s what you would have heard on the radio 80 years ago today, from the Pittsburgh Press, April 27, 1942. In addition to the broadcast band listings, the paper carried shortwave listings for programs from Moscow, London, Rio de Janeiro, Vatican City, Lima, and Guatemala City.

To see a larger version, click on the image above.

Image courtesy of Gerald Ford Presidential Library Facebook page.

Census data about individuals is private for 72 years. I assume that the thinking is that after 72 years, nobody really cares how much money you made or other details of your personal life.  So after 72 years has elapsed, the information becomes public data.

Since census day was April 1, 1950, this means that the data for the 1950 census was made available on April 1, 2022. The census data for 1940 has been available online for ten years, and you can easily search it by many criteria, including name, at this link at Ancestry.com.  (In fact, if you just Google the person’s name and “1940 census,” you’ll probably find the data that way. All of the original images of these records are available at the U.S. Archives website, but they cannot be searched by name on that site.

The images of the original 1950 records are now available at the U.S. Archives, which promises that the records can be searched by name. However, since most of the records are in cursive writing, the OCR process is not yet quite up to the task. However, it promises that the Artificial Intelligence is going to engage in machine learning. In particular, users are requested to transcribe entries, and I believe the thinking is that the AI is going to use these examples to learn the handwriting of individual enumerators, the people who went door to door writing down the data about the people at each house.

If you do try to search by name now, you’ll need to use a little creativity.  In many cases, the last name is transcribed wrong, in which case you probably won’t find it.  But if you search for just the first names in such a case, you might find the household, especially if you can narrow down the location well enough.  But as the 1940 data proves, the searchability of the 1950 data is bound to get much better.

It took some searching, but I found my parents and grandparents. It was necessary, however, to know their address in 1950, at least approximately. Once you know where someone lives, you can find their “Enumeration District” with the interactive map at Ancestry.com.

Armed with this information, you can enter the Enumeration District, County, and State at the Archives.gov website.

You will then find a listing of all of the households in that neighborhood. Most of those listings seem to be about 25 pages long, and they are organized in the order in which the enumerator walked through the neighborhood knocking on doors. After you see which end they started on, it’s usually fairly easy to guess about which page the person of interest is on, and scroll through the pages to find them.

The example above is for then-Congressman Gerald R. Ford at his home in Washington, D.C. Since he was a member of Congress, the information for his household is struck out, with a notation that it will be transferred to his home district in Michigan.

The census contains the basic biographical data for everyone in the country. For about one person out of five, the enumerator was instructed to ask a few additional questions. My mother was one of those five people, and from her entry, I learned that in 1949, she earned a salary of $1600 per year working 41 weeks as a stenographer.

Sixty years ago this month, the March 1962 issue of Electronics World showed how to put together this five transistor metal detector, using either 2N188A or 2N524 transistors. While these PNP germanium transistors are probably no longer manufactured, there are New Old Stock (NOS) specimens still to be found. However, the circuit is quite common in cheap metal detectors, and it’s probably most cost effective just to buy one from one of the links below.

If you’re looking for a very basic kit to build, the final link below is a one-transistor oscillator, which you use in conjunction with an AM radio for a rudimentary metal detector.

This type of metal detector is often sold as a toy, and the kids soon lose interest, or the parents confiscate it because of the annoying squeal. But they can actually work quite will, with just a bit of patience and practice.

This beat-frequency circuit consists of two identical oscillators, both tuned to the same frequency of about 100 kHz. One of them uses a coil mounted inside the case, and the other uses the search coil. When a metallic object comes near the search coil, that oscillator changes frequency. You start by tuning both to the same frequency, meaning that they become “zero beat,” and no sound comes out of the speaker. But when one oscillator changes frequency, and audio tone is heard, its frequency being the difference between the two oscillators. As long as you tune it carefully to zero beat, this type of detector is very sensitive. They’re regarded as toys because most kids don’t bother with the careful tuning part.

The secret of using this type of metal detector is to practice.  Toss some metallic objects on the floor, set the unit so that the tone just barely disappears, and then see how it reacts to those objects.  You’ll normally find that occasional re-tuning is necessary as the batteries get lower.

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We previously showed you a radio at left that was sure to delight the youngsters of 1939.  It featured a creepy face with eyes that lit up in time with the music.

Not to be outdone 23 years later, the publishers of Popular Mechanics published in the March 1962 issue the plans for the same general idea shown here. This time, the face, a clown, was a little bit less creepy, but it still had magic eye tubes in the place of eyeballs, and the eyes flashed in time with the music. The magazine gave two options for the project. If you didn’t have a radio to spare, then you could build the entire radio, which was basically a crystal set using 1N34 diode, with two tubes to provide loudspeaker volume. The magazine noted that this worked satisfactorily in downtown Chicago, and pulled in three different stations with a 50 foot antenna on the roof. According to the magazine, this simple circuit was “the minimum performance which might satisfy youngsters.”

But for better performance, it was recommended to just use an existing radio, and tap in the additional circuit, shown below, to flash the eyes. The magazine showed a template for cutting the clown face, but also noted that the prepunched chassis and clown face were available from the Experimenter’s Supply Co., 1924 W. Columbia Avenue, Chicago.