One hundred years ago this month, the March 1926 issue of Boys’ Life showed how to build a crystal set for only 80 cents. And the radio editor, Zeh Bouck, even suggested some ideas for shaving that cost to a little less. (He also pointed out that the headphones could be had for $3.) Tuning was accomplished by a slider on the coil, and the author points out the importance of making sure the slider makes contact with only a single wire. One tip was to wind thread between individual windings.
Seventy years ago, the March 1956 issue of Radio Electronics showed this circuit for a sound-powered transmitter, which could be built into a telephone handset. Power was provided by rectifying the output of the microphone.
For some actual contacts made with a similar transmitter, see the writeup about the New England Code Talker QRP transmitter.
If you were in the market for a radio in East St. Louis a hundred years ago, then you would want to get yourself down to Barney’s, 10th and Washington, (on Saturday, where they were open until 9) and get a Crosley model 50 one-tube set, for only $3.98, about the same price as an extra pair of pants for your $9.90 suit.
The ad appeared in the East St. Louis (IL) Daily Journal, March 5, 1926.
If that wasn’t in the budget, you could take home a crystal set for less than the cost of a pair of shoes. In either case, headphones, unless you already had a pair, would be an additional $1.98
Sixty years ago this month, the cover of the March 1966 issue of Electronics Illustrated featured the “Mini-Mitter,” a compact and lightweight (28.5 oz.) 15 watt transmitter for 40 meters. The construction article, is written by Russ Alexander, W6IEL, whose work we have seen previously. He notes that the radio weighs less than the missing power transformer. No transformer was necessary for two reasons. First, the 50-volt tubes were wired in series (along with a 130 ohm 5 watt resistor) directly to the AC power. And the B+ was courtesy of two solid-state diodes wired as a voltage doubler to produce about 310 volts.
The first day on the air, the author, in California, worked both the East Coast of the U.S., but also a 579 report from Sakhalin Island, Russia.
As shown here, the transmitter was constructed with two chasses. The front contained the controls, meter, and tuning indicator. The rear panel was for mounting the tubes and crystal, and for the key and antenna connections.
The other piece of news heralded by the magazine cover was the appearance of a new column in the magazine, questions and answers by “Uncle” Tom Kneitel, then K2AES, whom we have previously featured.
Contest automation in Amateur Radio is nothing new, as shown by this illustration 70 years ago in the March 1956 issue of QST. “Jeeves” was, of course, a common character in the Gil cartoons that filled the pages of QST for many years. If you’re looking for more, you can find them in this collection, available at Amazon.
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Seventy-five years ago this month, the March 1951 issue of Popular Science showed how to put together a science fair project that was, for many years, quite popular. You can make your own cloud chamber, which allows you to watch cosmic rays and the decay of atomic particles. It’s rather easy to make. You make a supersaturated layer of alcohol vapor, which is done with the use of dry ice. The only other materials needed can be found around the house.
The alcohol can be ethyl, methyl, or isopropyl. If Junior is taking it to school, it’s probably best to avoid ethyl alcohol. In addition, that kind (in the form of “Everclear” most likely) is more expensive than isopropyl, which can be had at any drug store.
Dry Ice can be found at the better convenience stores in your area. Of course, use caution when handling it. Actually, you shouldn’t handle it at all. Bring an insulated container to the store and have them place it in there.
Fifty years ago this month, the CB column in the March 1976 issue of Popular Electronics carried some pointers for CB’ers to be prepared for emergencies. Included was this simple circuit to ensure that the radio could see uninterrupted service in the event of a power outage.
A trickle charger keeps the 12 volt battery ready to do at all times. And the 4PDT relay ensures that switchover is automatic. (If you can’t find the 4PDT, two DPDT relays would work just as well.)
Edit: I just noticed that the diagram is wrong. Can you spot the error? Post a comment below.
Shown here 85 years ago this month in the February 1941 issue of Practical Wireless is the receiving station of Ronald Rose of Birmingham, England. At the left is a five-tube superhet, and at the right is a four-tube set. It also includes a wavemeter and speaker.
With a 75 foot inverted L, Rose routinely tuned in stations in America, Australia, and Panama.
Sixty years ago, the February 1966 issue of the British Radio Constructor showed a refinement in light beam communication. As we’ve shown previously, it can be done with a normal incandescent bulb. But there were two disadvantages. First, the bandwidth was quite low. And because the light source was spread out along the filament, it wasn’t possible to concentrate the light into an extremely narrow beam.
These problems were solved by the use of an arc lamp, specifically, a Sylvania Concentrated-Arc Lamp type A2, was used. The bulb necessitated a pulse of about 1000 volts, so some additional circuitry is required. The transmitter is shown here. The transistorized receiver is typical of other receivers, and is transistorized.
During daylight, the set was said to have a range of at least a quarter mile, and the bandwidth was 1000 Hz.
In what is, in our opinion, a shortsighted decision, Environment Canada announced recently that its VHF weather broadcasts will go dark starting March 16. Like in the United States, Weatheradio Canada broadcasts on 162 MHz frequencies from over 200 locations across Canada. In addition to weather conditions and forecasts in a computer-generated voice (in English and French), it uses SAME technology to activate alerts on radios. If there is a weather warning, your receiver will set off an alarm and wake you up.
For many people, this technology is obsolete, since their cell phone can do the same thing. But, in both the U.S. and Canada, there are many areas where cell phones do not work. But with an inexpensive receiver, the rather primitive technology employed by weather radios can provide a vital service to most of the continent. And weather radio can provide service to deaf persons, which might be problematic with other technologies.
Canada doesn’t seem to have a coverage map, and with 200 stations, the coverage probably isn’t quite as good as in the United States, where only a handful of truly remote places lack coverage. But the vast majority of the population has access to this service, even though many of those people don’t have cell service. And the cost is nominal. Each transmitter needs a few hundred watts of electricity to operate. The weather data is being generated anyway, and the system to broadcast it in two languages is completely automated.
You can read more about how weather radios save lives at our earlier post. And for specific information about how this technology can serve deaf persons, see this post. And Mexico also has its SARMEX network, which also includes earthquake warnings.
Unfortunately, I’m afraid that lives will be lost because of this unfortunate decision. I hope the United States, with its robust network of NOAA weather radio stations, will not make the same bad decision.