Tele microphone

This article or the following section is not adequately provided with supporting documents ( e.g. individual evidence ). Information without sufficient evidence could be removed soon. Please help Wikipedia by researching the information and including good evidence.

The telemicrophone ( Greek ) is a device specified by Ernest Mercadier in Paris in 1886 that connects the telephone and the microphone .

Two pieces of coal are attached to the phone plate to form the microphone. They are enclosed in a thin iron tube , and their pressure on the surface is regulated by a small auxiliary magnet . A thin slab of glass , mica or wood is spoken against , which is separated from the plate by a closed layer of air 1 cm thick. When speaking, the tele-microphone sends telephone and microphone currents at the same time, the latter with the help of an inductor role .