Electronic devices {amplifier}| {vacuum tube} {electron tube} can increase electric current.
tube
Vacuum tubes have a cathode emitter, anode collector, and zero to three positively charged screens. As it heats, cathode emits electrons {thermionic emission, amplifier}. Anode attracts electrons. Electric current flows from cathode to anode. Positive-charge electrodes {grid, vacuum tube} between cathode and anode attract electrons, to increase signal strength. Electric-signal wave frequencies do not change. Only amplitude increases.
solid state
Solid state transistor amplifiers have negative electrode transmitter and positive cathode collector, with positive electrode base between them. Current flows from transmitter to collector, as base attracts electrons, amplifying current.
The same vacuum tube or transistor {regenerative receiver}| can amplify an electric signal many times.
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Date Modified: 2022.0225