It all begun with liquid transmitter, which was the first transmitter developed by Alexander Graham Bell and Elisha Gray almost simultaneously, in 1876. And that later came to be known as liquid microphones.
This transmitter had a diaphragm attached to a funnel shaped mouthpiece. There was a metal pin at the center of the diaphragm, extended till the metal cup below, which contained a dilute acid. As the diaphragm moved, the pin also moved up and down and thus the difference in resistance could be observed. And for sound reproduction, the pin and the cup were connected to a battery and telephone receiver so that any sound in the mouthpiece was reproduced and came with lucidity.
Besides Bell, Elisha Gray was another inventor of the liquid microphones as both the experimentation had taken place simultaneously. Gray's liquid transmitter consisted of a diaphragm attached to a movable conductive rod dipped in acidic solution.
It also had a fixed rod placed beside the first one and was connected to a battery. The resistance varied with the separation in the rods, which was caused due to the variation in the sound pressure. Basically, the difference between Bell's transmitter and Gray's transmitter was the rod. Elisha Gray used brass rod instead of the needle.
However, in this way the first ever working microphone came into being. Though they are not in use at present but are the base of the superior models developed later (as for example, Thomas Edison who gave the device a new form).
Most amazingly, the liquid microphones are famous till date since the first phone conversation between Bell and Watson was through liquid microphone. However, later, these microphones were developed and were used for musical purposes.
David Edward Hughes was another inventor who developed the concept of microphone and thus modern liquid microphones appeared. His experiment was really amazing and different. He demonstrated the liquid transmitter by mounting it on a sound box that contained insects, whose scratching was considered to be amplified. The bottom line was that it worked for the ears the same way as the microscope worked for the eyes.
Later, other scientists like Majoranna, Chambers, Vanni and Sykes worked on the concept of liquid microphones to make it usable for clear sound reproduction. The base of this microphone was the liquid that was used, that even included water. There was a conception regarding water microphones that was developed even before liquid one but however, it proved to be impractical.
Majoranna used a reservoir that held the conductive liquid. He even used a voltage of 780 watts. And this gave birth to a new conception of using high current to build up microphones. C. Egner and J.G Holmstrom invented one of the high current microphones that were water-cooled and consisted of 16 separate carbon units. Voltages and current from 10 volts at 20 amperes to 30 volts at 10 amperes could be handled by connecting the units in different series.
In this manner the liquid microphones were transformed to modern ones and were used for various purposes in different times. Like during the World War I, then after that they were used for public address and later for broadcast in radio station, television and films.
