A triode(from three electrodes) was the
vacuum tube
equivalent to a
transistor. It consist of a vacuum tube
with an
anode, a control
grid and a
cathode filament.
simplified buildup
O-----. : |
) : |
( : |
Glow ) : |
current ( : |
) : |
( : |
) : |
O-----' : |
| | |
O O O
C G A
Legend
C Cathode
G gate/grid
A anode
To the
cathode filament a glow
current is
applied, this
is because
electrons is more 'willing' to leave a
heated
electrode. By applying a
voltage to the grid, a flow of electrons
to the anode is created. And by changing the grid voltage,
the flow can be controlled.
The triode is still used in some
amplifiers, but
due to lower
efficiancy it has mostly been replaced
by
transistors.