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. 12, 1989
Filed:
Sep. 10, 1987
Victor F Scheele, Ft. Wayne, IN (US);
Stephen E Youtz, Ft. Wayne, IN (US);
Hamilton Standard Controls, Inc., Farmington, CT (US);
Abstract
A fail safe drive circuit for enabling the relay which in turn opens the valve for supplying gas to a burner is disclosed and includes a pair of field effect transistors both of which must be operating properly to enable the relay. One transistor receives an enabling input from a rectifier circuit and will be enabled only if the alternating input signal is of sufficient magnitude and repetition rate. The other transistor is turned on and off by the alternating input signal and the gas valve will be turned on only when each of the transistors is operating in its intended mode. The circuit thus discriminates against false enabling signals such as a direct current signal, line voltage signal, a non-repetitive alternating current signal, or other spurious signal.