The addition of an intermediate electrode control by Lee De Forest, helped develop the first electronic component amplifier: the triode. The triode consists of an electron emitting cathode, an anode receiver and a screen placed between the two. By modulating the voltage applied to the gate from the cathode, a greater or lesser number of electrons emitted by the cathode to the anode arrive, creating a variable current between anode and cathode. Load in series with the anode converts the current variation in voltage variation and power: the amplification is carried out.

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