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. 25, 1984
Filed:
Sep. 04, 1981
William F Hill, Stafford, GB;
Lucas Industries Limited, Birmingham, GB;
Abstract
A control circuit for an electromagnet includes a main current control element in series with the electromagnet winding and controlled so as to switch on and pass a 'pull-in' current for an initial period and to control the current to a lower 'hold' level during a subsequent period. A capacitor is connected in series with a diode and a transistor across the winding and the transistor is controlled to switch on during the change from 'pull-in' to 'hold' so that the capacitor is charged up during this change. A second transistor is connected in series with a second diode to permit reverse current flow from the capacitor to the winding during switch-off to hasten collapse of the flux in the winding and overcome the drop-out delaying effect of eddy currents in the electromagnet core.