1977 Fish Attractor

1977101projectsWe previously showed you the modern electrical method to catch worms.  (In fact, if you catch too many for your fishing needs, we even showed you how to make big money selling worms.)  But now that you have all of those worms, you’ll want to take them fishing, and this electronic project from 40 years ago practically guarantees that the big ones will start biting.

The circuit puts out a repeated click-click sound which is reportedly a dinner bell for fish.  With this circuit in a suitable waterproof container, the fish will be biting in not time.

The circuit appeared in the 1977 issue of 101 Electronic Projects, a special edition put out by the publishers of Elementary Electronics.

1967 Homemade Galvanometer

1947AprRTVExpStudents looking for a simple but meaningful science fair project involving electricity won’t go wrong in constructing a simple galvanometer. The instrument can easily be constructed in an evening at little or no cost, and will prove to be very sensitive in detecting even small electrical currents.

The plans shown here appeared fifty years ago in the April-May issue of Radio TV Experimenter.  The plans are very straightforward, and most students can probably figure it out simply by looking at the diagram here.  It consists of a normal compass (even the most inexpensive toy version will work just fine) surrounded by a coil of wire.  When hooked to a battery, the compass will immediately deflect.

The sensitivity of the instrument is illustrated by using it to test a “dead” battery.  Even though an old battery is incapable of putting out enough current to run anything, it will still show a deflection if hooked to the galvanometer.

For students wanting to do something a bit more extraordinary, the homemade galvanometer can be paired up with one of the homemade batteries we previously profiled.  Most of the parts can be found around the house or at the closest dollar store.  Just about any type of insulated wire will work just fine.  If you can’t find any wire at the dollar store, you should be able to find some donor electronic device at the dollar store and you can scavenge the wire from it.  They’re not really necessary for the project, but if you want to match the design of the one shown here, the two “Fahnestock Clips” for hooking up the battery are available at Amazon.

Station D-E-B-U-N-K, 1942

1942Apr12ChiTribSeventy-five years ago, the April 12, 1942, issue of the Chicago Tribune carried this story about a wartime curiosity on the shortwave bands, Station DEBUNK.

After the United State entered the war, the station sprung up on 7.2 MHz, and tried to pass itself off as a clandestine station operating from inside the United States.

But according to the newspaper, the FCC had confirmed what most SWL’s had already figured out, namely, that the station was broadcasting from Europe. The newspaper noted that the station was on the same frequency as the Berlin shortwave station.

The newspaper also noted that many listeners saw the hand of Freddy Kaltenbach in the station’s appearance, noting that it expressed his manner of expression and thinking. We previously wrote  (here and here) about propagandist Kaltenbach, a former Iowan of German birth.

The station was also profiled in the April 18, 1942, issue of Radio Guide, which noted that the station normally signed on to its 41 meter frequency between 7:30 and 8:00 PM Central War Time. The transmission began with an interval signal consisting of a piano playing part of the melody from the Star Spangled Banner, repeatedly playing the music for the words “by the dawn’s early light.”

The announcer then asked listeners to phone their neighbors to tune in and then played some jitterbug records. After about ten minutes, the announcer, one “Joe Scanlon” unleashed propaganda that was “anti-British, anti-American, anti-Communist, anti-Jewish, in fact, anti everything but National Socialism.”

After the diatribe, the station would sign off with the Star Spangled Banner. The Radio Guide profile noted that the station was amateurish in nature, with “the modulation as rotten as the talks.”

Announcer “Scanlon” was actually Herbert John Burgman, originally of Hokah, Minnesota.  Burgman served in the U.S. Army from 1918 to 1920, posted in Germany. In 1921, he was employed as a clerk at the U.S. Embassy in Berlin and married a German national. By 1941, he was a committed Nazi sympathizer, and declined repatriation to the U.S. along with the rest of the embassy staff, and he signed on as a propagandist for Radio DEBUNK.

After the war, he was arrested a tried for treason. The prosecution relied not only eyewitness testimony, but the recordings of the broadcasts from the FCC’s Silver Hill, Maryland, monitoring station. Despite a plea of insanity, Burgman was convicted of 13 acts of treason and sentenced to 6-20 years in prison. In 1951, the Court of Appeals affirmed his conviction. Burgman v. United States, 188 F.2d 637 (D.C. Cir. 1951).
He died in prison in 1953 at the age of 59.  He then found his way home to Minnesota and is buried in Austin, MN.

You can listen to a sound clip of Station DEBUNK at this link.

1947 One Tube Broadcast Regen

1947AprPM1947AprPM2Seventy years ago this month, the father-son team shown here at the kitchen table couldn’t decide which of them was going to get the one-tube radio after they finished putting it together. But fortunately, the circuit was simple enough that they decided to simply make two of them, one for each. They are following the plans that appeared in the April 1947 issue of Popular Mechanics.

The set was billed as being for the beginner, and both easy to build and simple to operate. It used a single 6J5-GT tube as the regenerative detector, and could pull in standard broadcast stations with good headphone reception up to about 400 miles. To keep things simple, it used a transformer to supply the 6 volt filament current, but used a 45 volt battery to supply the B+.

1947AprPMchasisConstruction was made easy by the “semibreadboard” chassis shown here, consisting of two wooden slats mounted on two wooden strips. The two slats were spaced so that the tube socket could be mounted between them, eliminating the need to cut a large hole for the socket.

The magazine promised that the next month’s issue would show how to convert the set into a more powerful all band 4-tube set, although the one-tube design was more than adequate for the beginner who simply wanted to build a set to pull in local stations.


RCA TP-16A Television Projector, 1947


This RCA ad from the April 1947 issue of Televiser shows how film was broadcast in the early days of postwar televsision. The prewar stations generally had no way to broadcast prerecorded programming. The ability to use film meant that the television production business was a bit less frenzied, without the need to have some live action going on every moment the station was on the air. Film was still a lot more expensive than the later alternative, video tape, but the ability to use film meant that news and entertainment could be shown on a delayed basis. And since there was no live distribution between most cities, the ability to use film also mean that programs could be shipped to other stations, albeit on a delayed basis.

The RCA TP-16A Television Projector, shown at the left, was a self-contained unit which converted film to video. The unit at the right was a two-piece unit, with the film projector at left and video camera at right. The advantage of the dual unit was that it could be used with two film projectors, a mirror being used to switch from one to the other on the fly.

16mm film was already an established format, but there was one problem that had to be overcome. The 16mm format used 24 frames per second, while the video was 60 frames per second. Synchronization was accomplished according to the diagram at the lower right corner of the ad.

The film fed normally at 24 frames per second. During the first frame, the film was illuminated twice, at 1/60 second intervals, and the frame was scanned twice. The net effect was that half of the film frames were scanned three times, and the others scanned two times, for an average of 2-1/2 video frames per film frame. This resulted in the 24 frame per second film being scanned 60 times per second.

The 1000 watt incandescent bulb lit only about 1/1200 second. The video camera had enough inherent memory that it could complete the scan even though it was unlighted.

Battle of Vimy Ridge, 1917

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The Battle of Vimy Ridge, painting by Richard Jack. Canadian War Museum via Wikipedia.

220px-Canada_flag_halifax_9_-04Today marks the 100th anniversary, April 9, 1917, of the start of the Battle of Vimy Ridge.

The battle was part of the opening phase of the British-led Battle of Arras in the Nord-Pas-de-Calais region of France, and involved four Canadian divisions against three German divisions.

The Canadians objective was to take control of the high ground, in order to ensure other troops could advance without German fire. The Canadians captured most of the ridge during the first day of the battle.

The battle marked the first occasion when all divisions of the Canadian Expeditionary Force participated in a battle together, and became a symbol of Canadian national achievement and sacrifice.

free-vector-poppy-remembrance-day-clip-art_106032_Poppy_Remembrance_Day_clip_art_smallBritish and Canadian losses totalled 3598 dead and 7004 wounded.

Bataan Death March, 1942

Today marks the 75th anniversary of the start of the Bataan Death March,
which began on April 9, 1942. After the fall of the Philippines, the Imperial Japanese Army forcibly transferred between 60,000 and 80,000 American and Filipino prisoners of war. The prisoners were marched about 60 miles and then placed on trains.

During the march, between 5000 and 18,000 Filipino solders died, as did between 500 and 650 Americans. The march was later judged to be a Japanese war crime.


Amateur Radio Shut Down, 1917

QST, April 1917.

QST, April 1917.

With the declaration of war, Amateur Radio in the United States was shut down for the duration.  Both transmitting and receiving were banned, and amateurs were required to take down their antennas.

The official order was printed in QST, May 1917:

Office of Radio Inspectoor

To all Radio Experimenters,


By virtue of the authority given the President of the United States by an act of Congress, approved August 13, 1912, entitled “An Act to Regulate Radio Communication,” and of all other authority vested in him, and in pursuance of an order issued by the President of the United States, I hereby direct the immediate closing of all stations for radio communications, both transmitting and receiving, owned or operated by you. In order to fully carry this order into effect, I direct that the antennae and all aerial wires be immediately lowered to the ground, and that all radio apparatus both for transmitting and receiving be disconnected from both the antennae and ground circuits and that it otherwise be rendered inoperative both for transmitting and receiving any radio messages or signals, and that it so remain until this order is revoked. Immediate compliance with this order is insisted upon and will be strictly enforced. Please report on the enclosed blank your compliance with this order, a failure to return such blank promptly will lead to a rigid investigation.

Lieutenant, U.S. Navy,
District Communication Superintendent

US At War: April 6, 1917

One hundred years ago today, April 6, 1917, the United States entered the First World War when Congress declared war on Germany.  President Wilson, in an address to a joint session of Congress on April 2, had asked for the declaration, citing unrestricted German submarine warfare and the Zimmermann telegram.  The Senate passed the resolution on April 4, with the House following on the morning of April 6.