Monthly Archives: May 2022

Automatic Radio Timer: 1942

1942MayPS11942MayPS2Eighty years ago, the May 1942 issue of Popular Science offered this solution for those who wanted to make sure they heard the latest war bulletins, but didn’t want the radio on at other times. With this system, the radio would turn itself on hourly, at the top of the hour, to play the latest news report. Then, it would shut itself off automatically until the next one.

This was accomplished with a clock (preferably an electric one, for better accuracy) modified as shown here. The glass was removed, and the switching unit here was installed. It consisted of two pieces of springy brass. When the minute hand came around, it would close the contacts and turn on the radio. For larger sets with more current draw, it was recommended to use auto breaker points. A switch in parallel would allow you to turn the radio off and on manually.

The recommendation was to set it to come on about 30 seconds before the hour, and shut off six minutes later, which would ensure being able to hear all hourly news broadcasts, with time for the set to warm up.



Simple 1962 Shortwave Tuner

1962SpringRadioTVExp4This young man is pulling in the shortwaves courtesy of an extremly simple circuit which appeared in the Spring 1962 issue of Radio-TV Experimenter.

The radio consisted of a crystal set, feeding into an audio amplifier module. The amplifiers were available from Lafayette and other retailers, and drove a speaker. The receiver itself consisted of just a germanium diode, along with coil and capacitor. The coil is wound on a ferrite core, and is seen protruding from the top of the set.

Despite the simplicity, the author was able to pull in signals from the strong European shortwave broadcasters with only a short antenna and ground. The set tuned about 3.5 to 7 MHz.

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1942 One Tube Receiver

1942MayRadioCraftpEighty years ago this month, the May 1942 issue of Radio Craft showed how to put together this simple one-tube receiver. Being a battery set, there was no need to worry about hum, and the batteries were inexpensive. The B+ voltage was only 7.5 volts, so even with a large dry cell for the filaments, the battery cost was only 58 cents.

The set used a 1S4 tube as regenerative detector. It had two bands, which were switched by moving an alligator clip on the antenna coil. The overall tuning range was 480 kHz through 2.5 MHz, meaning that it covered the entire broadcast band, plus a little bit above and below. Thus, the set could also be used to pull in ships as well as police broadcasts.

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