Fifty years ago this month, the March 1969 issue of Popular Electronics carried this quiz on Ohm’s law. A few of the questions have some tricky aspect that you might need to notice, but they can all be solved with the familiar E=IR equation.
Answers will appear here tomorrow.
Seventy-five years ago this month, the March 1944 issue of Radio Craft magazine contained this interesting idea for using a burnt out fluorescent tube as a radio detector. Even though the filament is open, current can still flow from one end to the other through the ionized gas, and apparently it can rectify.
The magazine also showed how the tube could be used as an audio oscillator, as shown in the diagram below.
Even though there were wartime parts shortages, the experimenter could probably get his hands on a burnt out lamp.
Shown here are students at South Side High School in Rockville Centre, New York. During the club’s two year history, fifteen members had obtained FCC licenses. This included three girls, and the majority of the current class studying code were also girls.
The club station call sign was K2LAK, and was under the direction of the school’s industrial arts director, Miles Stireman, K2KAT. Shown at left at the National NC-300 and Johnson Valiant are members Diane Anhel, KN2LLB, and Ed Davis, K2PHK.
The photos appeared in the March 1959 issue of Electronics Illustrated.
Eighty years ago this month, the March 1939 issue of Radio Retailing magazine carried this ad for an interesting looking mobile shortwave converter.
From ABC Radio Laboratories of 3334 N. New Jersety St., Indianapolis, IN, the Model 600 covered the 49-16 meter bands. It noted that the unit was “especially adapted to use in tropical countries and the more remote parts of the world.” The set retailed for $24.95.
Also shown was a converter that tuned 1500-2600 kHz to pull in police calls “for use of police and other law enforcement officers.”
The unit is a bit reminiscent of the Gonset shortwave converter, which came out in the late 1940’s. I actually had one of the Gonsets installed in a vehicle in the late 1970’s, and it was a fairly sensitive receiver until one day when the magic smoke leaked out. Since the solid-state car radio wasn’t capable of supplying B+, I used a separate vibrator power supply.
Decades before the CIA teleported a young Barry Soetero to Mars, an Englishman was busy communicating with the red planet, as shown from this clipping from the March 1929 issue of Science and Invention.
Dr. Hugh Mansfield Robinson (a doctor of laws), shown standing with the headphones in the photo, had previously communicated telepathically with Mars. He followed up with a message sent by the the British Post Office radio station at Rugby (at a cost of 18 pence per word) on 18,240 meters (16.4 kHz). Since the Martians preferred 30,000 meters (10 kHz), he listened on that frequency, as shown in this picture.
Dr. Mansfield Robinson reported that he did receive a reply. Unfortunately, he was not able to translate the reply. More information is available at the BT archives.
Seventy-five years ago this month, the March 1944 issue of Radio Craft magazine presented this idea of how invading forces could blanket the enemy with radio by sky. The idea was to alert civilians as to the invasion and give instructions. The expendable 500 watt transmitters shown here would be dropped over the teritory in question and would broadcast a prerecorded message from magnetic tape or wire. Another possibility would be to drop PA systems, which would begin playing at 3000-4000 feet.
The advantage of this system was said to be that the aircraft could leave the area immediately. In more recent times, the U.S. military has, indeed used airborne transmitters, but stationed in the aircraft.
Each year, the March issue of Popular Mechanics carried the plans for a receiver dubbed the “Little Giant.” The rendition 80 years ago in the March 1939 issue was this four-tube TRF receiver complete with built-in phonograph. While the set was not especially designed for beginners, the magazine noted that the set was not difficult to build. It was billed as a portable, but the magazine noted that it could be adapted into an old console or large table cabinet.
With a 20 foot antenna, the set would get the local stations with surprising volume. And with a 50 foot antenna, the set would pull in more distant stations. It weighed in at 16 pounds, and could provide entertainment for vacationers, as shown above, or could provide entertainment and dance music as shown at the left. “Phonograph records may be played and amplified when broadcasting stations leave the air.”
Sixty years ago, the March 1959 issue of Electronics Illustrated showed how to change your own picture tube, including diagrams for common configurations of both horizontal and vertical chases. The article explained how to short out the capacitors in the power supply, lest the handyman get zapped by high voltage from a set that wasn’t even plugged in. And it also explained how to avoid shards of glass flying everywhere if the tube imploded.
But it was the magazine’s cover that offered the reminder that to do this sort of job, you really ought to put on a sport coat. And while it’s not visible in the photo, it seems likely that this home repair man is wearing a tie.
Forty years ago this month, the March-April 1979 issue of Elementary Electronics carried this tribute to Tandy Corporation founder Charles D. Tandy, who had died of a heart attack at the age of 60 in November 1978. Tandy was best known in the electronics world as having purchased the fledgling Boston Radio Shack chain in 1963. The author of the magazine was none other than Lewis Kornfeld, the president of Radio Shack both before and after Tandy’s purchase.
According to Kornfeld, nothing made Tandy angrier than empty hooks in the parts department. He questioned why there could be even a single out-of-stock item when “I’ve made your life simple by eliminating thousands of slow movers.”
Tandy got his start in the leather business, and while serving in the Navy during World War 2, he noticed sailors being taught knitting and needlepoint as part of their recuperation. He believed the men would prefer leatherwork, and established a system of craft work for the hospitalized men.
Seventy-five years ago this month, this ad in the February 1944 issue of Service magazine asked where all of the radios in Manila were. The Japanese flag and soldier gave the answer, namely, that the invaders took them.
The ad noted that of all war weapons, radio was one of the most important. “it unites the free peoples in a common purpose and links them instantaneously with their Governments. It maintains the power to resist of the conquered. It unites and aims the hammer blows of armies.”
America had 59 million radios, and it was the patriotic duty of the radio serviceman to keep those receivers functioning. The reminder came from the Jackson Electrical Instrument Company of Dayton, Ohio, which provided the tools to do just that.
