Diaphone

The Diaphon is a compressed air-driven foghorn.

The Diaphon based on the movement of a slotted piston in a cylinder and was built in 1903 (according to other sources 1910) the mechanic and inventor John Pell Northey, a professor at the University of Toronto patented. It is based on one of Robert Hope -Jones, an emigrant to America British electrician and organist, developed sound generator. This tone is also the basis for the famous Wurlitzer organ.

The Diaphon generates a main sound of, typically about 250 Hz When switching off the tone generation device the sound even slightly, but with a lower frequency of about 100 to 150 Hz, this results in the typical " snort " of Diaphons. This grunt is under certain circumstances due to the lower frequency continue to hear as the main tone.

The first Diaphon was installed in 1914 in Buffalo, State of New York, in order to improve the safety of navigation on the Great Lakes.

In addition to its role as fog horns were and Diaphone also be used for generating alarm signals in cities.