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:
Sep. 23, 1980
Filed:
Feb. 26, 1979
Applicant:
Inventors:
Leif A Persson, 252 62 Helsingborg, SE;
Tord P Lundin, Billesholm, SE;
Assignee:
Other;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H03G / ;
U.S. Cl.
CPC ...
179 / ; 307237 ; 179 / ;
Abstract
Each of a pair of ear pads is provided with an electrically-operated earphone. The earphones are connected to each other by a circuit having a cord for connecting the earphones to an external audio-signal source. The circuit includes a pair of Zener diodes connected in back-to-back or opposed parallel relation to each other, and in parallel to the earphones so that if an incoming AC audio signal exceeds a predetermined value one of the diodes will fire to short the input signal, thus limiting the output (in decibels) of the earphones. A field-effect transistor is connected in series with the earphones to limit the current load thereto.