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:
Nov. 25, 1980
Filed:
Aug. 14, 1978
Harumi Horiuchi, Yokohama, JP;
Hideo Aoyagi, Otashi, JP;
Soundesign Corp., Jersey City, NJ (US);
Abstract
A noise-free electronic switching circuit selects one of a pair of audio input signals in an audio system. Each input signal is connected by separate conductors to a single output terminal. The output terminals of two transistors are respectively connected between each conductor and ground. When a manually-operated switch is switched to a first operating condition, an exponentially increasing and an exponentially decreasing control voltage are respectively applied to the bases of a first and a second transistor. When the actuating switch is switched to a second operating condition, an exponentially decreasing and an exponentially increasing control voltage are respectively applied to the bases of the first and the second transistor. In either operating condition, one transistor is turned on and the other is turned off. Thus, only the selected audio signal is delivered to the output terminal; and the other non-selected audio signal is shorted to ground before reaching the output terminal. The exponential nature of the control voltages reduces audible noise during switching in accordance with the method of the invention.