At first it was usual to join the microphone transmitter in the direct circuit.
He wore headphones and spoke into a microphone, simultaneously responding to half a dozen chat windows open on this computer.
Hughes invented the microphone, but did not apply for letters patent.
Another type of microphone which was used in Europe much more than in the United States was the multiple-contact instrument.
The resistance of the microphone can thus be made a large fraction of the total resistance of the circuit in which it is placed; hence by using considerable currents, small variations in its resistance can be made to induce somewhat powerful currents in the line wire.