Transmitter

—1. In telephony, the device into which the speaking is done so that undulatory currents are set up in the line by means of which the sounds of the voice are transmitted. The modern transmitter is of the granular carbon type. It contains two flat carbon electrodes, one mounted on a vibrating diaphragm and the other stationary. Between them is introduced a ma of granular carbon. The vibration of the diagram caused by the voice transmits variations in pre ure through the electrodes and carbon grains and thus varies the resistance of the circuit. 2. In telegraphy, the key used for sending signals over the line. It consists of a pivoted lever with a finger piece. When depre ed it closes the circuit through the line, and when released it rises and opens the circuit, transmitting dot and dash signals according to the Morse code. 3. In wirele telegraphy, a sending key which controls the duration of the sparks at the spark gap thereby sending out the waves in groups cor- Te ponding to the dots and dashes of the Morse code.