This woman appears to have a high level of admiration for her lamp. And the admiration is well deserved, since it’s not just a lamp. Instead, it has a four-tube radio receiver in its base, with the loudspeaker at the top. A single plug-in cord provided power to both the radio and the lamp, and the lamp was available in several color combinations.
It was shown 85 years ago this month in the January 1939 issue of Popular Science.
Eighty-five years ago this month, the January 1939 issue of the British magazine Practical Mechanics carried the construction plans for this two-tube shortwave receiver. The exact circuit is a little hard to follow, since the magazine included no schematic diagram. Instead, only the pictorial diagram below is shown. But the left knob served as coarse tuning, with the center knob for fine tuning. The control on the right appears to control regeneration.
Eighty years ago this month, the January 1944 issue of Radio Craft carried this circuit for a receiver to run directly from 32 volts. Specifically, a reader requested a circuit that would “work from a 32-volt lighting system.” The circuit used three tubes, 1T4, 1S5, and 1S4. The filaments were in series with a 550 ohm resistor, and 32 volts was sufficient for the B+.
The “32-volt lighting system” was undoubtedly a Delco Lighting Plant, designed for lighting up the farm. It consisted of a motor generator which charged 16 2-volt batteries. The generator would kick in automatically when the batteries needed charging, and shut off when they were fully charged.
The only mystery here is the reader’s return address, New York City. While some parts of the city had DC power at the time, it was 110 volts. He must have been designing the circuit for someone on the farm without electric service.
I remember this colorful receiver on the cover of Elementary Electronics for January 1974. It was a basic regenerative receiver, and used an audio amplifier module to drive the speaker. But it was more than a radio, it was a circuit for the electronics experimenter to play around with something new, the varactor diode.
As the accompanying construction article noted, even though most radio components had gotten quite small, the tuning capacitor was the limiting factor, since they couldn’t get much smaller. For radios to be as small as they are today, something different was needed, and that ws the varactor diode. When reverse biased, many diodes act as a capacitor, with the capacitance varying with the voltage. Some varactor diodes were on the market, but this circuit allowed you to swap out random diodes and see how they performed. To get the circuit working, you could put a 100 pF capacitor (or maybe a standard 365 pF variable) between J3 and J4, and make sure the set was working. Then, you could try out various diodes and see how they perform.
I also remember the cartoons below, from the same issue. In this case, there was no capacitor to capacit, but the varactor took the honors instead.
Sixty years ago this month, the January 1964 issue of Electronics Illustrated noted that it had been just over six decades since Marconi bridged the Atlantic without wires or ships in 1901. In the intervening years, the job had been done with satellites such as Telstar I and II.
But on July 26, 1963, a new experimental satellite, Syncom, had been launched from Cape Canaveral. The satellite was new in that it was synchronous. Its orbital period was 24 hours, so it seeming hovered at the same longitude. Since it was launched from 33 degrees north, it actually did a figure 8, hovering between 33 north and 33 south. But that was good enough to be continuously visible from both America and Europe and 22,300 miles.
The magazine noted that if such a satellite were launched from the equator, then it would stay above a single point on the earth’s surface. The magazine didn’t use the word, but this is what we know today as a geosynchronous orbit, although most geosynchronous satellites are today launched from other locations, first into a geostationary transfer orbit before being maneuvered into geosynchronous orbit. According to the magazine, the satellite’s two transmitters put out about 2 watts on 1915 MHz.
A hundred years ago this month, the December 1923 issue of the British journal Wireless Weekly showed how to build this two-tube regenerative receiver. The exact frequency/wave length coverage is not stated (quite likely because the author didn’t really know for sure), but it was designed to receive long wave radiotelephone and radiotelegraph signals, as well as BBC broadcasts. So presumably, it covered the long waves and the medium waves.
It was said to pull in all of the BBC broadcasts with good volume.
The circuit isn’t all that different from similar receivers from subsequent decades. So it would be a good performer, even today. The picture above is somewhat deceptive, as it doesn’t show the components below the chassis. It is designed to be mounted in a a box about 3 inches deep, which is shown in the article.
Seventy years ago, this young man was deriving new enjoyment from his train set, thanks to the voice control system his dad put together, from the plans in the December 1953 issue of Popular Electronics.
The system would cycle through forward, stop, and reverse commands. The actual words used didn’t matter, but with a bit of creativity, Junior could make it look like the device understood exactly what he said. For example, if the train was moving forward, then barking “stop” would have the desired effect. From a stop, the word “reverse” would do the trick. If the train was going backwards, then “now go forward” would give three syllables, making it cycle through to the forward mode.
The device was compatible with both Lionel and American Flyer train sets.
Seventy years ago, it was a Hi Fi Christmas for soprano Mimi Benzell and her husband Walter Gould. They are shown here with what Santa delivered, namely, a Graarard turntable, a Pilot tuner, a Bogen amplifier, a University speaker enclosure, and a Wilcox Gay tape recorder.
They are probably shown at their home, which, according to Wikipedia, was at 45 Cardinal Road, Manhasset, New York. The picture appeared on the cover of the December 1953 issue of Radio News.
The December 1943 issue of Radio News carried the plans for this simple one-tube code oscillator. The 117N7 with a built-in rectifier meant that it could be done with a single tube.
The author of the article is one R.C. Zaun, an engineer with the Thorardson Electric Manufacturing Company. Not surprisingly, the most expensive part shown in the schematic is probably the audio output transformer, which just happens to have a Thorardson part number.
As shown here, the oscillator had a pitch of about 1600 Hz. This could be varied in one of two ways. First, R1 could be replaced with a variable resistor, although the article noted that this would also affect the volume. Another method would be to change the value of C4, switching in capacitors of different values to vary the pitch.
If wartime parts shortages meant that the 117N7 wasn’t available, it could be substituted with other versions of a different filament voltage. Of course, an appropriate dropping resistor would need to be used.
This ad appeared 75 years ago this month in the December 1948 issue of Practical Mechanics.
Your choice of headphones was important. For DX work, you needed good fidelity. But more importantly, you needed to uphold British prestige. And to do that, you needed the Type K headphone from S.G. Brown, Ltd.