Monthly Archives: September 2016

1966 GE Rechargeable Portable

1966sepelecworldFifty years ago, the September 1966 issue of Electronics World showed this General Electric transistor portable with a rechargeable battery.  It came with a detachable base containing a clock, which also served as the charger.  The battery was said to power the set for up to twelve hours after an overnight charge.

As seen from the headline, one notable feature was the fact that the set contained integrated circuits, and GE engineers predicted that all of their products would contain IC’s by 1970.

Citing the set’s reliability, GE offered a three year warranty, including the battery.

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Babi Yar, 1941

Soviet investigators view opened grave at Babi Yar, 1944. U.S. Holocaust Memorial Museum photo.

Soviet investigators view opened grave at Babi Yar, 1944. U.S. Holocaust Memorial Museum photo.

Today marks the 75th anniversary of one of the largest acts of mass murder to take place during the Holocaust, the massacre at Babi Yar, on the outskirts of Kiev, Ukraine. On September 29 and 30, 1941, 33,771 Jews were killed at that ravine.

German forces entered the city on September 19, 1941. Prior to the German invasion, about 160,000 Jews had resided in the city, about 20% of the population. About a hundred thousand fled in advance of the Germans, and most of those remaining were women, children, the elderly, and the sick.

Wikipedia image.

On September 29, the German military government issued the order shown here, requiring all Jews in the city to report, along with documents, money, valuable, warm clothing, and blankets.

The Nazis conducted the operation with efficiency. The Jews were ordered to proceed and give up first their luggage, then their coats, then their outer garments and shoes, and finally their underwear. By the time they knew what was happening, it was too late. By the time they heard the machine gun fire, there was no chance of escape.

They were led to a ravine about 150 meters by 30 meters. At the bottom of the ravine, they were made to lie down on top of Jews who had already been shot. A marksman, standing on the layers of corpses, then shot each in the back of the neck.

The corpses were then buried in the ravine, and the money, valuables, clothing, and even underwear was distributed to local ethnic Germans.

Wikipedia photo.

Shown here is Dina Pronicheva (1911-77), one of the handful of survivors of the massacre. She initially claimed that she was not Jewish and was only seeing someone off. The Germans decided to kill her anyway so that she would not be a witness. She played dead in a pile of corpses as the Nazis covered the mass grave with earth. She was eventually able to exhume herself. She was the only survivor to testify at the Kiev war crimes trial.

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Radio On The Farm, 1926

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Shown here ninety years ago in the September 1926 issue of Radio Age magazine is Charles Ostrand, described by the magazine as a farm boy from Shawnee County, Kansas. He built the three tube set shown here in order to listen to helpful agricultural programs. The magazine reported that he had built several other sets for his neighbors.

This was not an unusual phenomenon. According to the magazine, there were already a million radios on the nation’s farms, and the U.S. Department of Agriculture predicted that the number would soon double. The radio, according to the magazine, was not just a device for entertainment. It delivered weather and market reports, as well as vital scientific information of use to farmers.

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1966 Adding Machine

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Fifty years ago, electronic calculators were things of science fiction, and even adding machines were expensive. The little circuit shown here filled a few of the gaps. It appeared in the September 1966 issue of the British Radio Constructor magazine.

According to the author, the device was built in response to a request by a friend who needed an adding machine to be used at motor car rallies in order to tally the number of miles covered.

It consisted of a telephone dial, a relay, and an electromagnetic counter, the type that increased by one every time a pulse was applied. The telephone dial had normally closed contacts, so the relay was necessary to convert to individual pulses. Also, the author noted that the telephone dial contacts probably couldn’t handle the current required by the counter.

The end result was that the counter increased by one for each pulse. So if you wanted to add 3+3, you would dial 3 twice, and the counter would count to 6.

Two-digit numbers could be accomplished by dialing zero for each 10. So to dial 34, you would dial zero three times, and then 4.

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1936 Four Tube Portable

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The picnickers shown here in the September 1936 issue of Popular Science are enjoying a radio program, thanks to the compact portable broadcast set shown here. It was light enough to take in a car or canoe, worked indoors or out, and could provide loudspeaker volume. The four-tube battery superheterodyne design was said to rival the performance of any all-electric set, but the article promised that anyone could build it.

The tube lineup of the set was 1A6, 1A4, 1B4, and 1F4, and was powered by five batteries: Two 45-volt B batteries provided 90 volts to some parts of the circuit, and 45 to others. Filaments were powered by two 1.5 volt dry cells, and a 4.5 volt C battery was also used. The batteries were packed snugly in the bottom of the case, behind the 6-1/2 inch permanent magnet speaker. The cabinet, covered in luggage canvas, was both attractive and durable.

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Science Fair Project: Atomic Frog Clock

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Here’s a picture of the time signal coming from the Eiffel Tower a century ago, as shown in the September 1916 issue of Wireless Age.

They were the results of experiments by one Dr. Lefeuvre, professor of physiology at Rennes University. The experiments were apparently carried out a few years prior, before the war, since they were also reported in the February 1913 issue of Popular Mechanics.

1913pmfroglegThe Eiffel Tower signals were received at a distance of 230 miles, and most remarkably, the mechanism for recording them was a frog’s leg, using the apparatus shown here.

Even though Prof. Lefeuvre conceded that there was no practical application to his system of “muscle writing,” it was regarded as a highly interesting laboratory experiment.

The sciatic nerve of the leg, cut below the knee, was spliced into the audio output of the receiver, with one end of the leg pinned securely to a base, and the other end connected to a lever. A pen recorded the impulses on the rotating drum.

Unfortunately, the “frog’s leg and its nerve do not retain their sensitivity very long,” precluding commercial application.

The experiment was, of course, an updated version of Luigi Galvani‘s 1780 experiment showing the frog legs could be made to twitch by application of static electricity.   Aspiring young mad scientists could probably develop an interesting science fair project along the same lines.  Instead of the Eiffel Tower time signals of a century ago, modern students in America could use the signals generated by WWV.  The now common “atomic clocks” rely on signals from sister station WWVB.  A bright student could quite easily construct a similarly accurate version, using the same user interface developed by Galvani over two centuries ago.  You might get some inspiration from this video:

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1966 One Transistor Regen

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One reason why simple transistor radio circuits proved challenging for early transistor experimenters was the low input impedance of bipolar junction transistors. This made it difficult to come up with an efficient circuit for a one-transistor radio.

But by 1966, the problem was largely solved by the appearance of the field effect transistor (FET), whose electrical characteristics were essentially identical to those of a triode vacuum tube. Fifty years ago this month, the September 1966 issue of Electronics Illustrated carried the plans for this one transistor regenerative receiver for the broadcast band.

The circuit used a Texas Instruments 2N3820, which sold for $3.75 plus shipping, and put out good headphone volume with a single transistor.

1966septeischematic

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Univ. of Minn. Electrical Engineering Bldg., 1926

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1926septradiobroadcastjanskyShown here ninety years ago is the Electrical Engineering Building at the University of Minnesota, from the September 1926 issue of Radio Broadcast magazine.

The magazine reported that the entire top floor of the building consisted of communication laboratories, principally devoted to radio instruction.  It was under the direction of Prof. C.M. Jansky, Jr., who believed that the program was the equal of any in the United States.

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WGU-20, “The Last Radio Station”

WGU-20 logo. Wikipedia image.

Forty years ago, the Spring-Summer 1976 issue of Communications World carried an interesting profile of station WGU-20, sometimes dubbed “the last radio station.”

The station was built at a cost of two million dollars in 1973, and operated with a power of 55 kW on 179 kHz with a 700 foot toploaded vertical antenna located at Chase Maryland. It was operated by the Defense Civil Preparedness Agency.

The station was designed to be the first in a network of longwave stations constituting the Decision Information Distribution System (DIDS) to warn the public of an enemy attack. An additional stations, operating on 167, 171, and 191 kHz were to blanket the continental United States with coverage, controlled by 61.15 kHz control stations at Ault, Colorado, and Cambridge, Kansas. In the event of an attack warning, civil defense authorities would send the alert to these control stations by landline or microwave, and the DIDS network would commence playing taped messages warning the public.

The station did QSL, and the magazine provided the mailing address for reception reports.

The network was never built, and the WGU-20 antenna was ultimately demolished in 2011. While it was operational, the station broadcast the time of day:

Good evening. This is WGU-20, a defense civil-preparedness agency station, serving the east central states with emergency information. Eastern Standard Time seventeen hours, twenty minutes, twenty seconds. Good evening. This is WGU-20, a defense civil-preparedness agency station, serving the east central states with emergency information. Eastern Standard Time seventeen hours, twenty minutes, thirty seconds. Good evening. …

The video below contains a recording of WGU-20, and was recorded at a later date after weather broadcasts were included in the broadcast:





Rock Radio, American Samoa, 1944

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Shown here are Radio Technician First Class Kenneth D. McCoy of Salem, Oregon; Radioman First Class Stanley T. Dixon of San Francisco; and Radioman Third Class Charles H. Wilson of Steubenville, Ohio, the operators of 2-1/2 watt “Rock Radio,” located in 1944 in American Samoa. The picture and accompanying article appeared in the June 1944 issue of Radio News.

The station was cobbled together with scavenged parts including “tired tubes, broken bed springs, and stripped Jeep gears.” The station’s microphone consisted of the receiver of a Marine field telephone. The record player was an antiquated Victrola purchased for $3 from one of the natives.

Each night, the station came on the air, manned by whichever of the three was not on duty that night. It signed on with an almost worn out recording of the Star Spangled Banner, followed by a variety program of recordings chosen at random by the announcer. After a fifteen minute newscast, requests were taken. On Christmas Eve, the station recorded and rebroadcast the President’s message to the armed forces.

The station’s signal covered the entire island, and proved popular with the sailors and marines stationed on the island.