The coherer is no good for this purpose, since it either stops the current entirely or lets it flow copiously.
In Marconi's first instruments he used a device called the "coherer."
We now found that the coherer would respond when the spark coil was operated several feet away.
One wire from the coherer is connected to the aerial and the other to the ground.
The coherer may be said to resemble an engine-driver, and the “relay” an engine.
In this wire—as a part of its circuit—is placed the coherer.
The “coherer,” invented by Branly in 1891, is a glass tube containing metal filings between two circuit terminals.
The method of using the coherer to detect electric pulses is not due, however, to Marconi.
We are now in a position to examine the apparatus of which a coherer forms part (Fig. 61).
Using this apparatus now as a transmitter of ether waves, we found that the coherer detected them.