IPC Main Group
H04R 21/00 Variable-resistance transducers
Introduced: September 1968
Last revised: January 2006
Classification Context
- Section:
- ELECTRICITY
- Class:
- ELECTRIC COMMUNICATION TECHNIQUE
- Subclass:
- LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
Scope Notes
Limiting references: Gaseous resistance transducers Magneto resistive transducers
2 direct subcodes
Child Classifications
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- H04R 21/02 Microphones
- H04R 21/04 Gramophone pick-ups using a stylus; Recorders using a stylus