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Title:
NOISE PREVENTING FILTER OF CARRIER FREQUENCY BAND OF CARRIER TYPE INTERPHONE
Document Type and Number:
Japanese Patent JPS60121810
Kind Code:
A
Abstract:

PURPOSE: To prevent noise to a interphone by providing an electric wire with a parallel circuit of a retardation coil and a capacitor which has a resonance frequency in the frequency band of a carrier type interphone and also capacitors at the power source side and load side in parallel.

CONSTITUTION: The retardation coil 18 having current capacity coordinate with a breaker for branching of a distribution board in terms of short-circuit capacity during the short-circuiting of load equipment and a capacitor C19 parallel to it are provided between the electric wire and load equipment. The resonance frequency between the coils 18 and C19 is set close to the carrier frequency band of the carrier type interphone, and a constant is so determined to obtain high impedance to the carrier frequency band of the frequency band of the interphone and extremely low impedance at the commercial frequency. Further, C20 and C21 are provided between power source-side terminals 14 and 15 and load side terminals 16 and 17 of this resonance circuit. The C20 and C21 absorb high frequency noises generated various equipment utilizing a high frequency inverter to prevent noises from flowing through the electric wire, and evil influence of the noises upon the carrier type interphone is prevented.


Inventors:
Watanabe, Susumu
Yokose, Yoshikazu
Kamimura, Ryoichi
Application Number:
JP1983000230116
Publication Date:
June 29, 1985
Filing Date:
December 06, 1983
Export Citation:
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Assignee:
MATSUSHITA ELECTRIC IND CO LTD
International Classes:
H03H7/01; H03H1/00; (IPC1-7): H03H7/01



 
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