Assertion: electronic amplifier | /r/CapableOf | use vacuum tubes
Facets:
value: from the 1920s
type: TEMPORAL
value: to increase power
type: PURPOSE
Source sentences:
text: A valve amplifier or tube amplifier is a type of electronic amplifier that uses vacuum tubes to increase the amplitude or power of a signal.
text: Before the commercial introduction of transistors in the 1950s, electronic amplifiers used vacuum tubes (known in the United Kingdom as "valves").
text: From the 1920s until the 1950s, electronic amplifiers used vacuum tubes.