
Amplifiers
Thermionic valves
Although valves have been long superseded by transistors and
ICs for general use, they still have their devotees, and they
seem to be growing in popularity for hi-fi amplifiers. Old valve
radios are now sought after by collectors and may also appear
in the workshop for repair.
Triode The simplest amplifying valve consisting of a
cathode heated by a filament, a control grid and an anode.
Electron flow from cathode to anode passes through the grid
which modulates it according to the voltage applied to it.
Although having a lower gain than the tetrode or pentode it has
a straighter characteristic and so produces lowe ...