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:
Oct. 14, 1997
Filed:
Feb. 27, 1995
Michael B Meeker, Kenosha, WI (US);
Snap-on Technologies, Inc., Crystal Lake, IL (US);
Abstract
A calibrating pickup circuit detects, using primary and secondary pickups, the primary and secondary voltages of an ignition coil of known turns ratio. The pickup circuit includes a programmable gain amplifier, responsive to the detected secondary voltage waveform signal and to a gain control feedback signal for generating an amplified secondary voltage waveform signal wherein the feedback signal has an initial predetermined value in calibration mode and has a calibration value in signal monitor mode. A waveform multiplexing circuit is selectively operable in calibration mode to alternately sample the primary and the amplified secondary voltage waveform signals over a predetermined period to generate a single interlaced waveform signal. Waveform comparison is then performed by evaluating the single interlaced waveform signal and a secondary-to-primary ratio calculated representative of the signal strength difference between analogous portions of the primary and the amplified secondary voltage waveform signals A calibration value is then determined on the basis of the secondary-to-primary ratio and the known turns ratio of the ignition coil.