The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 17, 1979
Filed:
Feb. 24, 1978
Applicant:
Inventors:
Susumu Sueyoshi, Tokyo, JP;
Hideo Ito, Tokyo, JP;
Assignee:
Pioneer Electronic Corporation, Tokyo, JP;
Primary Examiner:
Int. Cl.
CPC ...
H03F / ;
U.S. Cl.
CPC ...
330298 ; 307360 ; 330257 ;
Abstract
A circuit for detecting a DC signal in the output of an audio amplifier 1 and for uncoupling a speaker SP in response thereto comprises a low-pass filter 2 whose output is coupled to one input of differential amplifiers 5, 6 whose other inputs are unbalanced by respective positive and negative threshold biasing potentials E.sub.1, E.sub.2. The differential amplifiers are directly connected to respective current mirror circuits 7, 8, and their high impedance side collector outputs are applied to the inputs of an OR circuit whose output in turn controls the speaker uncoupling.