Drive-In Educational Programs and Meetings for COVID-19

DriveInCLEI’ve previously written about why I believe outdoor spaces should be utilized for learning and other group activities during the COVID-19 emergency. Since I’m in the business of providing continuing education programs for attorneys, a few weeks ago, I presented an outdoor program at a city park.

The weather for that program was excellent, and everyone enjoyed the opportunity to be outside. However, the weather can be unpredictable, and it won’t always work to be outside. For that reason, today, I presented a live drive-in program in a parking lot. The attendees watched from their car, and listened on their car radio. If there had been questions or feedback, they could have phoned me at any time.

Why a Drive-In Program?

It was a bit more work, and it would actually have been more pleasant to just get out of our cars and do it outside, as with the previous program. But a drive-in program is a very viable option for any group that needs to be meet in person, since the weather won’t always cooperate completely.

I didn’t bring it today, because the weather was nice, but if there had been a chance of rain, I would have brought a canopy such as the one shown here.  For an outdoor presentation of any kind, the speaker obviously needs to dress for the weather.  But the attendees can take advantage of their car, or even run the car for heat or air conditioning if needed.

My transmitter was the  InfOspot Talking House transmitter, which I previously reviewed.  As expected, my transmitter easily covered the parking lot.  I parked near a tree, and tied the end of the 10 foot antenna to a convenient branch.  I should have tested everything, since the audio quality wasn’t quite as good as I had expected.  In most of my tests at home, I fed the transmitter with an MP3 player, and the audio quality was absolutely astounding.  Today’s audio quality was quite good–certainly good enough for a lecture.  But if the transmitter was used for any kind of musical presentation, it wouldn’t have been quite good enough.  I’ll need to experiment with a different mike, or possibly run the existing mike through a preamp and feed the auxiliary input rather than the mike input.  (The audio quality through the line-in jack is excellent, so if you’re broadcasting from a location where another PA system is in use, that’s the best option, but you will need an inexpensive isolation transformer to prevent 60-cycle hum.)

Caveat Emptor:  The Importance of a Legal Transmitter

When buying a transmitter, it’s important to buy a transmitter that is legal.  Unfortunately, most of the transmitters in use for drive-in events these days don’t appear to be legal.  In particular, it would be very difficult to use a legal FM transmitter for an event such as this, because FCC rules (section 15.239) limit the transmitted signal to an extremely low level.  Amazon and eBay are full of FM transmitters that claim to be legal for unlicensed use, but even a cursory examination of their specifications reveal that their power level is many times what is allowed.  On the other hand, the rules governing AM transmitters (section 15.219) are much less restrictive.  The  Talking House transmitter is certified as complying with this section of the rules, and has a very good range for this type of use.  It is, therefore, the transmitter that I recommend for this application.  Chances are, nobody will complain to the FCC.  But if they do, and especially if there is interference with aircraft communications, which are near the FM band, the fines are typically in the range of $10,000.  It’s best to use a transmitter that you know is legal, and the Talking House is.

Here’s another writer who agrees with me that most FM transmitters used for this purpose are illegal.  As he puts it, they are all lying when they say on eBay or Amazon that they are legal.  And in my experience, as both a lawyer and a licensed radio engineer, he’s right.  Some of the listings claim that the transmitters are FCC certified.  In some cases, the certification appears to be for use by a licensed radio station.  In one case, the transmitter appeared to be certified for unlicensed use.   I checked the FCC website, and sure enough, there was a report from a Chinese lab certifying that the transmitter was compliant.  The report even contained test results showing compliance with some of the requirements.  But noticeably absent was any report showing that the transmitted field strength was compliant.  It couldn’t have been, because the transmitter was using hundreds or thousands more times power than allowed.  It appears than an overworked FCC simply failed to notice that this critical measurement was missing from the report.  Let the buyer beware.  Just because an eBay listing says that a product is legal doesn’t mean it’s legal.

A Good Way to Conduct In Person Meetings

As with my previous program, we could have just as easily done it over the phone, or via Zoom.  But some activities are best done in person, and after a long quarantine where everything has been done remotely, it’s refreshing to interact with others in person, even if they are six feet away and/or on the other side of a windshield.  Creatively making use of outdoor locations, whether it’s for business, education, or worship will serve an important role until things get back to normal.  And history tells us that yes, eventually, things will get back to normal.



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V-J Day

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Today is the 75th anniversary of the end or World War II.

After the atomic bombings of Hiroshima and Nagasaki on August 6 and 9, 1945, surrender quickly followed. The Japanese communicated their intention to surrender on August 15 Japan time, which was the evening of August 14 in the United States. While the official U.S. date for V-J day was the date of the surrender in Tokyo Harbor, September 2, V-J Day was celebrated in the United States the night of August 14 and August 15. The newspaper shown here is the Milwaukee Journal, August 15, 1940.

US Navy photo, via Wikipedia.

US Navy photo, via Wikipedia.



1940 Lafayette One Tube Kit

1940LafayetteOneTubeEighty years ago, the beginner couldn’t go wrong with this one-tube radio kit from the 1940 Lafayette catalog. For $3.95 (plus tube, batteries, and headphones) he or she could put together this set and pull in broadcast stations, both local and distant.  And for only 98 cents more, they could buy coils to cover four shortwave bands from 16 to 200 meters.



A Preview of Postwar Television

1945AugSepNRNWhen this issue of National Radio News, August-September 1945, went to press, the war was still raging in the Pacific. But the end was in sight, and despite the cynicism of skeptics, the editors of the magazine knew that television’s role in the postwar electronic era was a foregone conclusion, “witness the rapt attention of these comely lasses as they view the screen of the General Electric receiver.”



1940 Toy Submarine

1940AugPSIf Junior is looking for a spectacular science fair project that can be built at little expense, but still uses a slightly dangerous chemical, he can’t go wrong building this real submarine, according to plans contained in the August 1940 issue of Popular Science.

When released in the local pond, the submarine repeatedly submerges and surfaces, all the time moving forward in the water. The secret of all of this is a small amount of calcium carbide, the same chemical used in old-fashioned miner’s lamps. When the chemical is exposed to water, it generates a high pressure gas, which is used to propel the vessel and provide buoyancy. The chemical is readily available at Amazon, and probably at your friendly local hardware store.

School will eventually reopen, so your young submariners can take advantage of their summer vacation to build and test the craft, which can be made out of scraps of sheet metal and tin cans. Soldering is required, but kids naturally enjoy working with molten lead. When school reopens and the science fair is on, the submarine can be used for a variety of scientific experiments involving buoyancy, propulsion, or chemical reactions. The teacher has probably seen old movies with miners wearing headlamps, but this will probably be their first exposure to the actual chemical used. A blue ribbon is almost guaranteed.

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1950 Five Tube Superhet

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1950AugPM2These lucky youngsters have probably been drawing Social Security for about a decade, but in 1950, they were tuning in a favorite program on this attractive five-tube radio put together by their dad and big brother. The internal circuitry was a typical “All American Five” superhet, with a tube lineup of 12SA7, 12SK7, 12SQ7, 50L6, and 35Z5 rectifier. Since this was an AC-DC set, the article cautioned that the screws holding the chassis to the wooden case should be covered up for safety.

The cabinet is designed to resemble a circus wagon. The front is carefully painted with red and white enamel paint, with wooden dowels making the cage. Then, after the paint has dried, animal decals are applied.

The plans appeared in the August 1950 issue of Popular Mechanics.

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1960 Loudspeaker Crystal Set

1960AugPE11960AugPE2Sixty years ago this month, the August 1960 issue of Popular Electronics showed how to make the holy grail of crystal sets: a crystal set capable of loudspeaker operation.

The author, Walter B. Ford, reported good reception, including loudspeaker volume on strong local stations. The set relied upon two secrets. First of all, it had two tuned circuits in the front end for maximum selectivity. It also used two 1N34A diodes in a voltage-doubling circuit. For weaker stations, headphones could be used, or it could be used as an excellent AM tuner for an external amplifier. But for the strong stations, it would drive the speaker, with no power source other than the received signal.

The ferrite loopsticks might be hard to find these days, although with a ferrite rod, you should be able to make your own.  More information can be found at this link.  More hints on sourcing the parts can be found at my crystal set parts page.

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Nagasaki

19450809Today marks the 75th anniversary of the bombing of Nagasaki on August 9, 1945.  The attack is reported here in that day’s issue of the Chicago Tribune.  If the Japanese needed further convincing to surrender, that day also brought news that the Soviets had declared war on Japan and were attacking Japanese forces in Manchuria.

The video below is a radio broadcast that day by President Truman promising that the bombings would continue until the Japanese surrendered.  The war would be over in a few days.



Light Bulbs as Dropping Resistors

1945AugPMThis photo isn’t as sinister as it looks, and nothing untoward is going to happen to the gentleman at the left. The photo is from the August 1945 issue of Popular Mechanics, and these gentlemen are dealing with wartime parts shortages. They’re doing an emergency repair on this set, and need some way to power the filaments of the six-volt tubes. The filament transformer they need is a wartime priority item, so they instead wired the filaments in series and used a 40-watt light bulb as a dropping resistor.

The picture is accompanied by a table showing the resistance of common lamps.



Science Fair Project: Moving-Coil Ammeter

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1970AugSciElecThe young man shown here is probably getting ready to collect his first Social Security check, but fifty years ago, he undoubtedly took home the blue ribbon at the 1970 Science Fair. His project was shown in the August-September 1970 issue of Science and Electronics. According to the magazine, the project would show off knowledge and understanding, but would also require dexterity with tools.

The project was a moving-coil ammeter, not unlike a commercially made meter movement. While the magazine didn’t use the moniker, this type of meter is also commonly known as a d’Arsonval meter movement, after Jacques-Arsène d’Arsonval. For less advanced students, the article referred back to construction articles for some more primitive meters, such as the hot-wire ammeter we previously profiled. Most of the meter’s mechanical parts were made of wood, so the project required some expertise in the wood shop. The form for the moving coil was made with balsa wood, whose light weight ensured a sensitive movement.

The finished product could be accurately calibrated by using a commercial VOM, a battery, and a potentiometer. Current readings were noted on the commercial meter, and then marked on the face of the homemade meter.

According to the article, if the builder used reasonable care and followed instructions, they would be assured of a good grade and congratulations from friends and teachers.  And fifty years later, there’s no reason to think the result would be any different.