CPC Subgroup
H03F 3/185 with field-effect devices (H03F3/187 takes precedence)
Full Title
Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements > Low-frequency amplifiers, e.g. audio preamplifiers > with semiconductor devices only > with field-effect devices (H03F3/187 takes precedence)
1 direct subcode
Child Classifications
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