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:
Jun. 10, 1980
Filed:
Apr. 12, 1978
John I Smith, Washington, DC (US);
Other;
Abstract
An economical Cds photoresistor is connected to the input of an operational amplifier. Logging diodes are connected in a feedback configuration with the operational amplifier through a galvanometer meter. The log of the ratio of the input currents to the operational amplifier is independent of supply voltage thereby permitting the use of a wide tolerance battery supply. The input of the operational amplifier and the meter are referenced to a voltage divider. A feedback connection regulates meter current independently of meter resistance that varies strongly with ambient temperature changes. Light-emitting diodes provide regulation against battery voltage variation, light for meter scale illumination, and an inherent, unfailingly diagnostic battery-check response.