What an oscillator does
The vacuum-tube oscillator is an extremely versatile device for the production of alternating electric currents.
The currents so produced are usually periodic, and often substantially sinusoidal.
The useful power output and incidental losses are provided by a power input, which is ordinarily a direct current.
The efficiency is commonly very low, in the order of a few per cent.
In high-power applications, however, where efficiency is important it is possible to obtain values of efficiency well over 50 per cent.
The most important feature of the vacuum-tube oscillator is the great range of frequencies which may be produced.
Frequencies as low as a hundredth of a cycle per second and as high as 50 billion cycles per second are now readily produced. Past experience indicates that both limits will be extended further.