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:
Jan. 08, 1980
Filed:
Jul. 17, 1978
Mitel Corporation, , CA;
Abstract
A transformerless two-way trunk circuit particularly useful for interconnecting a balanced lead pair and an unbalanced lead pair, with complete control over sidetone and signal level. The balanced lead pair is terminated with a first matching A.C. impedance and a second D.C. resistance means. A first transformerless circuit means applies an incoming signal from the unbalanced lead pair to the balanced lead pair, and a second transformerless circuit means applies an incoming signal from the balanced pair to the unbalanced lead pair. A third transformerless circuit means cancels signals from said first circuit means applied to the balanced lead pair to prevent them from being reapplied to the unbalanced lead pair, and a fourth transformerless circuit means cancels signals from said second circuit means applied to the unbalanced lead pair to prevent them from being reapplied to the balanced lead pair.