The plans for this one-tube–er, I mean one-valve–regenerative receiver appeared 85 years ago this month in the January 1939 issue of Practical Mechanics.

The article begins by noting that “the small receiver is apt to be despised in these days of 7 and 8 -valve superhets, there is still a very wide field of application for the simple one-valver. Many schoolmasters, for in- stance, have asked for details of a set which may be used as a demonstrating model, either for handycraft instruction, or to explain many of the theories underlying modern radio technique.”

The circuit relies upon a pre-made coil, which is no doubt unobtainium these days. But the article does describe how to make a very similar coil, which can be used with slight modification of the circuit. Either way, the set did tune both longwave and mediumwave bands, thanks to a band switch which shorted out the longwave portion of the coil. The set uses a D210, which is a British model, but almost any triode would probably work well.

Fifty years ago, the hobbyist with nimble fingers and a sharp eye could have their own digital watch, thanks to this project in the January 1974 issue of Popular Electronics.

If you bought one, it would set you back $200, but you could make your own for about $80. The construction article gave the source for the case, you could make the small PC board, or you could buy the whole thing as a kit. If the tip on your soldering iron wasn’t small enough, the article suggested attaching a piece of copper wire and filing down the end. Accuracy was said to be several seconds a month.

This utilitarian-looking three-tube British device appeared in Practical Wireless 75 years ago this month, January 1949. It has considerable utility, as it functions as both a regenerative receiver and signal generator.

The regenerative receiver, of course, causes oscillation that can be radiated through the antenna jack. But this circuit does one better, because it turns the audio amplifier into an oscillator, which modulates the signal. Therefore, when working on another piece of equipment, you have a handy source of tone modulated RF. And when you’re done troubleshooting your other device, you can tune in programs from 3000 to 10 meters. Thanks to the second harmonic, you can use it as a signal generator up to five meters.

The plans for this handsome one-tube receiver appeared a hundred years ago this month, in the January 1924 issue of Popular Science. The regenerative set, when used with a high-quality loudspeaker, was capable of producing volume to fill a large room, with but a single tube. The secret was the antenna coil, which served as an autotransformer to boost the signal in the regenerative circuit.

The set was both sensitive and selective. When tested in New York City, within a couple of miles of some strong broadcast stations, it easily pulled in more distant stations. And with a 100 foot antenna, the author reported pulling in Chicago with loudspeaker volume.

If you were in the market for a very nice radio a hundred years ago, you couldn’t go wrong with this four-tube Air-Way receiver. For only $114.50, you would get everything you needed, including a Perfectone speaker, a complete antenna, and both of the batteries. You could get it at The Hecht Co., 624 F Street, Washington. Of course, that was a lot of money, according to this inflation calculator, over $2000 in 2024 money.

If you couldn’t swing that much, you could head down to Haverford Cycle Sales Co., 522 10th St. NW (conveniently across the street from Ford’s Theater), and get this one-tube Savoy, Jr., which was guaranteed to pull in the DX stations clear and strong. It also came with everything you needed–radio, tube, batteries, antenna, and headphones. And with a small down payment, you could take it home with a promise to pay a dollar a week.

The ads appeared in the Washington Evening Star, January 18, 1924.