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:
Aug. 12, 1986
Filed:
Dec. 19, 1984
Ian J Harvey, Cricklade, GB;
Lucas Industries public limited company, Birmingham, GB;
Abstract
A drive circuit for an electromagnetic device including a solenoid includes a transistor in series with the solenoid and a current sensing resistor. A comparator receives a voltage signal depending on the current flow in the solenoid and by way of an 'AND' gate renders the transistor conductive when a control signal appears and non conductive when the current flow exceeds a set value. A first monostable circuit modifies a reference voltage applied to the comparator and reduces the set value of the current after a predetermined time so that the solenoid is initially energised at a high current value which is then reduced to a holding value. The circuit includes a second monostable circuit which causes the transistor to be switched on and off when the current has attained the high value and when the current is at its holding value.