DIFF Subgroup
H03F 3/181 Low-frequency amplifiers, e.g. audio preamplifiers
Introduced: July 1974
Full Title
Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements > Low-frequency amplifiers, e.g. audio preamplifiers
IPC and CPC are identically structured here. All 1 subcodes exist in both systems.
IPC defines codes here since 1974.
Child Classifications
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