Monthly Archives: January 2020

1960 Homemade Computer

1960EI2Sixty years ago, the gentleman shown here was undoubtedly the first one on his block to own a personal computer, since he built this one, as shown in the January 1960 issue of Electronics Illustrated.

The device was essentially a binary counter. The pulses from the telephone dial went to a series of six flip-flop circuits, and the total was shown in binary with the top row of lights. So to add, you just dial in the numbers you want to add, and then read the sum (in binary) on the lights.

Subtraction was also possible, since subtraction of a number was the equivalent of addition of the number’s complement. In this case, since the computer handles 6 digit binary numbers, it can display 0-63. Thus, the complement of a number is 64 minus that number.  The bottom row of lights showed the complement of the number shown in the top row.  (For example, the complement of 110000 is 001111.)

Multiplication was possible by repeatedly adding, and division amounted to repeatedly adding and seeing how many times the addition was necessary.

The author does conclude by noting that the computer was intended as a demonstration model. Accordingly, it had little practical use “unless the builder takes the time to study some of the readily available literature on computer techniques and mathematics. I do not recommend that anyone not familiar with high school mathematics attempt to construct it, as it will merely become a toy of limited value.”



Belmont BRC-571 “Clockette” Radio Clock, 1940

1940JanRadioTodayThis handsome device from 80 years ago wasn’t a clock radio. Instead, it was merely a radio clock, namely, a clock and a radio in the same enclosure, both of which operated independently. It is the Belmont Model BRC-571, also known as the Clockette, and it’s shown here in the January 1940 issue of Radio Today.

The set tuned 540-1720 kHz, meaning that it would pull in police calls in addition to standard broadcast stations. The clock was described as self-starting, and the radio was a standard 5-tube superhet, both of which were housed in a walnut cabinet.

You can see a nicely preserved example of the set at the Radio Attic Archives.



Postwar VHF Allocations

Screen Shot 2020-01-15 at 1.19.09 PMAs you can see, there were still a few tweaks to be made, such as the elimination of TV channel 1, and the exact limits of the FM broadcast band.  But by January 1945, the postwar allocations for the VHF and UHF spectrum were pretty much in place.  This chart appeared in the January 1945 issue of Radio Service Dealer.



Avoiding Telephone Annoyance, 1920

1920Jan19EveningLedgerFor those who are annoyed by noise while talking on the phone, then this device from a century ago would prove helpful. As shown, the earpiece covers both ears, ensuring that your call won’t be interrupted.

The picture appeared in the Philadelphia Evening Public Ledger a hundred years ago today, January 19, 1920.



1960 Squelch for Benton Harbor Lunchbox

1960JanElectronicsWorldSixty years ago this month, the January 1960 issue of Electronics World carried a simple modification for the venerable Benton Harbor Lunchbox, in this case, the Model CB-1 CB transceiver.

James Green, the Chief Engineer of WELO, Tupelo, MS. The station had purchased two of the sets for communicating with one of the station’s engineers “living in a rural area devoid of telephone services.” For that reason, the set was going to be in operation for 18 hours a day, and the constant rushing noise of the superregenerative receiver “simply could not be tolerated.”

Green came up with a simple solution to the problem. Contrary to what one might think, the voice peaks of a received signal are louder than the rushing sound. Therefore, he simply used a sensitive relay from the rectified output of the audio output transformer. Then, the volume was turned to just to the point where the voltage was too low to energize the relay coil. At that point, the relay switched the speaker out of the circuit. When a call came in, the voice peaks generated a higher voltage, and the speaker kicked in. A capacitor kept the relay engaged for a short time so that the relay wouldn’t chatter between words.

A switch bypassed the squelch, so that the volume could be turned up or down.

The remarkable thing about this article is that a rig as simple as the CB-1 was actually put to a business use. For those who malign CB, I’ve noticed that 11 meters is so quiet these days that it can probably be used for useful communications, just like it was 60 years ago. As shown below, CB rigs are dirt cheap, and an antenna can be made for next to nothing. For short-distance communications, they can be useful for many applications.



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Official BSA Radio Kits: 1960

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Sixty years ago, Scouts looking to put together their own radio receiver could head down to the local BSA authorized dealer and pick up one of these official BSA radio kits, as shown in the January 1960 issue of Boys’ Life magazine.

There were two sets for the standard broadcast band. A two-tube set for $11.95 had a built-in loudspeaker. For headphone use, the one-tube set sold for $7.25. Both reuquired batteries. The filaments on both sets ran off a 1.5 volt battery for 20 cents. The two-tube set’s 90 volt B battery sold for $3.95, and the one-tube set’s 22.5 volt battery sold for $1.50.

For Scouts who already had radio building experience, it was time to move up to the short waves. That set, which looks like a regenerative receiver with one or two tubes, sold for $15.95. It ran off standard household current, so no batteries were necessary. Headphones were an additional $2.95, and “3 extra coils,” presumably to tune the short waves, were $2 for a set.

There was also an official BSA crystal set sold complete for $2.95. We actually had one of these around the house when I was a kid, and the chassis for this set was the bottom of the cardboard box it came in.

Finally, for Scouts working on their code, the Official S-O-S Signal Set sold for $1.95 for a single unit, or $3.95 for two units. The mathematically astute will realize that you paid a nickel extra if you bought two, but that presumably included the wire to hook the two units together.

1960JanBL2This issue of the magazine also contained a reminder of the upcoming February Boys’ Life radio contest, and in anticipation, contained some SWL’ing pointers by none other than Tom Kneitel.  Kneitel’s article contained some tips for pulling in DX, and a listing of some of the loudest and most likely to be heard stations from 3.2 to 25 MHz.

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1960 Kit Building Venue

1960JanEIThe hottest night spot in Greenwhich Village 60 years ago was a loft at 732 Broadway. A wide cross section of New Yorkers gathered there–school kids, attorneys, mailmen, a concert violinist, and a lady psychologist. For a dollar an hour, they had access to a workbench, tools, soldering irons, and test equipment where they could assemble electronic kits.

The workshop was the brainchild of Dave Muirhead and Elliot Gorden, described by the magazine as experienced audio men. In addition to the physical facilities, there was plenty of expert advice available as the customers put the finishing touches on their Heathkits, Knight Kits, and Eicos.

That address is currently the home of Universal Musical Instrument Co. From their Yelp reviews, I wouldn’t be surprised if there were a few old Heathkits buried under the musical instruments. According to one review, it’s a great place for those building or inventing their own musical instruments in search of affordable parts. “The proprietor often will let you browse, chaperoned, once he understands what you are there for.”

The profile shown above appeared in the January 1960 issue of Electronics Illustrated.



Broadcasting and the 2010 Haitian Earthquake

U.S. Marine shows Haitian man how to operate crank radio. US Dept. of Defense photo.

U.S. Marine shows Haitian man how to operate crank radio. US Dept. of Defense photo.

Today marks the 10th anniversary of the catastrophic magnitude 7 earthquake that hit Haiti on January 12, 2010. The epicenter of the quake was about 25 kilometers west of the capital, Port-au-Prince, where tens of thousands died.

The actual death count will never be known, but estimates range from 100,000 to 316,000. The morgues were overwhelmed by the sheer number of bodies, and most were buried in mass graves.

Over a quarter of a million residences, along with 30,000 commercial buildings, had collapsed or were severely damaged. Not surprisingly, the country’s communications infrastructure was severely damaged. The public telephone system was totally unavailable, and cellular service was severely impacted.

A bright spot in communications was radio broadcasting. The Port-au-Prince region was served by 50 radio stations prior to the earthquake.  All but one of these, Radio Signal FM, were initially knocked off the air. Within a week, however, about 20 stations, including Radio Lumière, a Christian station serving most of the country, were back on the air. Radio Lumière’s staff moved the station’s equipment to a tent outside its main building in order to resume broadcasting. Also, within about a week, a French community broadcasting association had a 300 watt transmitter flown in from Paris.

Additional broadcasting came from foreign countries. The U.S. Air Force Commando Solo aircraft was broadcasting Voice of America programming in Haitian Creole, which was also transmitted from the VOA’s 1180 kHz transmitter in Marathon, Florida. The BBC World Service also launched a Creole service with information about aid and rescue programs, as well as messages from people trying to locate family members. Initially, broadcasts were on shortwave, but were later relayed by FM relays from stations in Haiti as they came on the air.

One of the first voices on the air came from station 4VEH in Cap-Haïtien. That city, in the north of Haiti, was largely unaffected by the quake, and broadcasts continued on its AM station and FM network. The 10,000 watt AM signal on 840 kHz, would be listenable 136 kilometers away in Port-au-Prince. But to make sure, the station quickly made arrangements with Trans World Radio (TWR) on Bonaire to simulcast the 4VEH program. While the distance covered was over 800 kilometers, the entire path is over saltwater, and TWR’s then-100,000 watt 800 kHz signal (it’s now 400,000) watts was beamed directly toward Haiti. It put in a formidable signal which could easily be picked up on even the most inexpensive AM radio. The Creole program from the Christian radio station shared both practical help and a message of hope.

For those without radios in Haiti, a number of groups distributed solar or crank radios in Port-au-Prince. Among these was the U.S. military, which distributed 50,000 radios in the city.

This story serves as a reminder of the importance of having a battery-operated radio available in case of disaster. Even though the cellular network is down, and there is devastation for many miles in every direction, radio signals can be picked up, even with an inexpensive radio, for hundreds of miles. A battery-operated radio is a minimum requirement, as long as you have plenty of batteries. A radio that can be operated with a hand crank and/or solar power is an even better option. Shown below are some inexpensive options.

Battery Radios

Solar and/or Crank Radios

U.S. CDC image.U.S. CDC image.

References



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Arvin Model 302 Radio-Phono

1940JanRadioRetailingIf you needed an inexpensive radio-phonograph 80 years ago, then the Arvin model 302 (brown with ivory trim) or 302A (ivory with chrome trim) was just the thing.  The four-tube (12SK7, 12SQ7, 50L6GT, and 35Z5GT) superhet would pull in the local stations, and the would also play either 10″ or 12″ records.

For full portability, a carrying case was available for only $2.95 extra.

The ad, which also shows a car radio, table radio, and portable, appeared in the January 1940 issue of Radio Retailing.