For the last hundred years, criminals might have been able to outrun the police, but they can’t outrun the radio, as shown by the cover of Radio News, January 1924.

The accompanying article by Armstrong Perry describes this radio car employed by Scotland Yard. While the truck runs at 40 MPH, the officer in back can chat with headquarters, other cars, or even an airplane overhead. The receiver had six tubes, and the transmitter was said to get out 30 miles.

One hundred years ago this month, the January 1924 issue of Popular Mechanics showed how to put together this simple crystal set, which had been submitted by one F.L. Brittin of Chicago. In the 1950s and 1960s, it appears the Brittin went on to become the magazine’s radio editor.

The set was said to cost about 65 cents to build, and had excellent results pulling in stations up to 20 miles away. The honeycomb coil is homemade, and the insulation is carefully removed along a path for the slider, which tunes in the stations.

If you want to duplicate this design, be sure to check out our crystal set parts page.

A hundred years ago today, these were your choices for radio listening, according to the January 11, 1924, issue of the Washington Times.

At 6:15 PM, for example, you could tune in an organ recital on KDKA Pittsburg on 326 meters (920 kHz). Or, if you preferred, WOR in Newark was running a lecture on Mouth Hygiene on 405 meters (741 kHz).

At 10:30, you could pull in Paul Specht and his orchestra on WJZ, New York, 455 meters (659 kHz). If you happened to have missed the show, you can buy his CD on Amazon.

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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.

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.