Showing posts with label History of Technology. Show all posts
Showing posts with label History of Technology. Show all posts

Sunday, May 10, 2015

Boy Genius Blocks Navy Wireless

Commander Albert C. Gleaves U.S.N. of the Torpedo Station in Newport, Rhode Island, had a problem. The government had installed a new wireless station for ship-to-shore communication but in 1906 they were experiencing interference from a nearby amateur radio operator.
My sign was GR. "GR GR GR," they said, "if you don't stop operating that coil, you will find yourself in the jug shortly." I answered by sitting on the key. I was such a nice boy! - Lloyd Manual, Wireless Age, Dec. 1916.

The Nashville American, 22 Feb 1906
The Nashville American, Feb. 22, 1906

The Navy investigated and discovered a teenage schoolboy who had converted a hen house into a "ham shack" and equipped it with a home-made transmitter. The meagerness of the radio set startled the professional wireless operators who examined it. A report was filed with the Navy Bureau of Equipment. Some of the components used to build the set were described in The Nashville American and included:

Friday, May 1, 2015

Experimental Wireless Station 1XX

The Radio Club at Brown University dates to the end of the First World War when the United States government lifted restrictions on the private operation of wireless equipment. Student amateur radio operators formed the new club during the Fall semester in 1919.

An early transmitter used on campus was described as "a ½ KW rotary spark set and a two step amplifier" in the September 1920 QST magazine. One of the call signs used was 1LAU which was assigned to student Herbert R. Grimshaw. The emissions from the crude transmitters used by amateurs during this time caused stations in the same geographic area to interfere with each other. President of the club E. Standish Palmer proposed a system for managing the problem:
"Providence has considerable QRM [interference] to overcome and some sort of a control station is being considered. Palmer suggests different hours for the different classes of communication and a visiting committee to go to the stations of the various amateurs who overstep and tune them up. This is a good idea. Help the young fellows out in every way possible. Make them feel as though we are helping and not trying to dictate to them."
Another transmitter was a home-made set with two vacuum tubes. The alternator used to generate the alternating current is not shown in the photo below. It produces an Interrupted Continuous Wave (I.C.W.) which, like the rotary spark gap described above, was used to send Morse code. These transmitters were not capable of voice communications.

Transmitter of station 1XX
Credit: QST, April 1921.

Monday, August 4, 2014

As the Bubbl Bursts

The invention of magnetic bubble memory was once seen as a revolutionary computer development - the wave of the future. It is now a nearly forgotten technology.
"Many persons expect that the most dramatic changes in digital systems will result from magnetic-bubble chips that could well hold a million or more bits in the not-too-distant future. Along with charge-coupled devices, these memories show promise of replacing magnetic tape and disks for small systems." [emphasis in the original]
- Understanding Digital Electronics, Texas Instruments, 1978
One of the more unusual computer objects that I've collected over the years uses this memory. It is called the QSB-11A Bubbl-Board. I was told by the person that sold it to me that it had been used in a system at Los Alamos National Laboratory. I have no idea how it was used. Given the nuclear research conducted there I sometimes wonder if I should check to see if it is "hot."

Magnetic bubble memory module

Thursday, July 24, 2014

Geared to the Stars

The telescope at Ladd Observatory uses a clock drive to compensate for the Earth's rotation and track the stars. Modern telescopes use electric motors but this one was built in 1891 before electric power distribution was common. The Observatory originally had gas lamps for lighting and the telegraph system was powered by "gravity cell" batteries. The telescope's mechanical clock drive is weight driven with the speed regulated by a centrifugal friction governor.

The clock drive showing the governor
A closeup of the clock drive showing the governor in motion.
An optical sensor and precision timer are used to measure the rotation rate.

Saturday, July 19, 2014

Prismatic Analysis

One of the projects that I've been working on is the Brashear astronomical spectroscope from 1891. We're trying to recreate the ability to record spectra using the original photographic plate holder. Here is the wooden plate holder mounted in place of the eyepiece assembly that is used for visual spectroscopy.


A focusing screen was created by mounting the ground glass in a foamcore frame that fits the plate holder.