This years JOTA kit is “The Morse Phone” inspired by the “Fullerphone”
The Fullerphone was devised in 1915 by then Captain (later Major General) Algernon Clement Fuller of the British Royal Corps of Signals to overcome the common use of earth induction to overhear communications in the closely packed trench warfare of World War I. The commonly used trench buzzer signals could be detected at distances up to 300 yards and speech at 100 yards with only rudimentary equipment from enemy frontline trenches. German listening posts were soon routinely intercepting frontline conversations at ranges of up to 600 yards.
The resulting Fullerphone overcame this problem by using a very small amount of direct current for signaling, making the potential range for overhearing its signals negligible. It first went into use on the Western Front in late 1915 and was ordered in large numbers. Fullerphones eventually replaced earlier equipment to the divisional and corps levels and were widely used (more than 23,000 of them) by 1918. They were also used on some submarine cable links.
Improvements in design continued (the Italians copied the idea in the 1930s), with the Mark IV of 1939 being easier to use and carry. It remained in widespread use during World War II, in part because it could be used over an operating telephone line without disturbing the voice service. An eight-stanza “Ode to the Fullerphone” was published in 1944 in Jimmy, the Royal Corps of Signals magazine in the Middle East. The Fullerphone was again used during World War II with submarine cables, achieving a workable range of 200 words per minute upward of 700 miles. The Mark V was combined with a telephone and made for use in tropical regions while the ultimate Mark VI could be fully immersed in water and still used.
Here are some pics of the little project: