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:
Dec. 14, 2004
Filed:
Mar. 10, 2003
Donald S. Foreman, Fridley, MN (US);
Russell D. Braunling, Eden Prarie, MN (US);
Darryl J. Wrest, Coon Rapids, MN (US);
Honeywell International Inc., Morristown, NJ (US);
Abstract
A micropower apparatus and method for milliohm resistance detection includes a drive circuit and a monitoring circuit. The drive circuit includes a step up current transformer that is driven by a square wave oscillator via a low pass filter and voltage-driven current source. The drive circuit drives a series arranged test coupon and reference coupon, the latter being exposed to the elements. The coupons are Kelvin connected to the monitoring circuit, which includes a pair of low noise, low offset pre-amplifiers, a pair of post amplifiers connected to outputs of the pair of pre-amplifiers, a pair of full wave rectifiers connected to outputs of the pair of post amplifiers, and a pair of low pass filters connected to the outputs of the pair of full-wave rectifiers. Resistance values of the test and reference coupons can accordingly be monitored ratiometrically to determine a state of a selected environment by, for example, detecting changes in electrical resistance due to corrosion of the test coupon.